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Optimum Profiles of Endwall Contouring for Enhanced Net Heat Flux Reduction and Aerodynamic Performance
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作者 Arjun K S Tide P S Biju N 《Journal of Harbin Institute of Technology(New Series)》 CAS 2024年第2期80-92,共13页
Successfully utilized non-axisymmetric endwalls to enhance turbine efficiencies(aerodynamic and turbine inlet temperatures)by controlling the characteristics of the secondary flow in a blade passage.This is accomplish... Successfully utilized non-axisymmetric endwalls to enhance turbine efficiencies(aerodynamic and turbine inlet temperatures)by controlling the characteristics of the secondary flow in a blade passage.This is accomplished by steady-state numerical hydrodynamics and deep knowledge of the field of flow.Because of the interaction between mainstream and purge flow contributing supplementary losses in the stage,non-axisymmetric endwalls are highly susceptible to the inception of purge flow exit compared to the flat and any advantage rapidly vanishes.The conclusions reveal that the supreme endwall pattern could yield a lowering of the gross pressure loss at the design stage and is related to the size of the top-loss location being productively lowered.This has led to diminished global thermal exchange lowered in the passage of the vane alone.The reverse flow adjacent to the suction side corner of the endwall is migrated farther from the vane surface,as the deviated pressure spread on the endwall accelerates the flow and progresses the reverse flow core still downstream.The depleted association between the tornado-like vortex and the corner vortex adjacent to the suction side corner of the endwall is the dominant mechanism of control in the contoured end wall.In this publication,we show that the non-axisymmetric endwall contouring by selective numerical shape change method at most prominent locations is advantageous in lowering the thermal load in turbines to augment the net heat flux reduction as well as the aerodynamic performance using multi-objective optimization. 展开更多
关键词 endwall contouring turbine VANE heat transfer phantom cooling coolant injection net heat flux reduction aerodynamic performance
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Corrugated surface microparticles with chitosan and levofloxacin for improved aerodynamic performance
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作者 Chang-Soo Han Ji-Hyun Kang +4 位作者 Eun hye Park Hyo-Jung Lee So-Jeong Jeong Dong-Wook Kim Chun-Woong Park 《Asian Journal of Pharmaceutical Sciences》 SCIE CAS 2023年第3期146-158,共13页
Corrugated surface microparticles comprising levofloxacin(LEV),chitosan and organic acid were prepared using the 3-combo spray drying method.The amount and the boiling point of the organic acid affected the degree of ... Corrugated surface microparticles comprising levofloxacin(LEV),chitosan and organic acid were prepared using the 3-combo spray drying method.The amount and the boiling point of the organic acid affected the degree of roughness.In this study,we tried to improve the aerodynamic performance and increase aerosolization by corrugated surface microparticle for lung drug delivery efficiency as dry powder inhaler.HMP175 L20 prepared with 175 mmol propionic acid solution was corrugated more than HMF175 L20 prepared with 175 mmol formic acid solution.The ACI and PIV results showed a significant increase in aerodynamic performance of corrugated microparticles.The FPF value of HMP175 L20 was 41.3%±3.9%compared with 25.6%±7.7%of HMF175 L20.Corrugated microparticles also showed better aerosolization,decreased x-axial velocity,and variable angle.Rapid dissolution of drug formulationswas observed in vivo.Lowdoses administered to the lungs achieved higher LEV concentrations in the lung fluid than high doses administered orally.Surface modification in the polymer-based formulation was achieved by controlling the evaporation rate and improving the inhalation efficiency of DPIs. 展开更多
关键词 CHITOSAN Organic acid LEVOFLOXACIN Corrugated surface aerodynamic performance
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Effect of Streamlined Nose Length on the Aerodynamic Performance of a 800 km/h Evacuated Tube Train 被引量:7
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作者 Xiaohan Zhang Yao Jiang Tian Li 《Fluid Dynamics & Materials Processing》 EI 2020年第1期67-76,共10页
The aerodynamic resistance of a train running in the open air limits the maximum speed that can be attained by the train.For this reason,evacuated tube trains(ETT)are being considered as valid alternatives to be imple... The aerodynamic resistance of a train running in the open air limits the maximum speed that can be attained by the train.For this reason,evacuated tube trains(ETT)are being considered as valid alternatives to be implemented in the future.The atmosphere in the tube,the so-called blocking ratio and the length of the streamlined nose are the key factors affecting the aerodynamic performances of these trains.In the present work,we investigate evacuated tube trains with different lengths of the streamline nose on the basis of computational fluid dynamics(CFD).The three-dimensional steady compressible Navier-Stokes equations are solved.The running speed of the ETT is 800 km/h and the blocking ratio is 0.2.Results show that with the increase of the streamlined nose length,the aerodynamic drag and lift forces of the head car decrease gradually,and the drag and lift forces of the middle car change slightly.For the tail car,the drag force decreases,whereas the absolute value of the lift force increases.At a speed of 800 km/h,a slight shock wave appears at the rear of the tail car,which affects the aerodynamic forces acting on the train. 展开更多
关键词 Evacuated tube train RESISTANCE aerodynamic performance streamlined nose
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Influence of ribs on train aerodynamic performances 被引量:2
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作者 苗秀娟 高广军 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第5期1986-1993,共8页
The influence of ribs on the train aerodynamic performance was computed using detached eddy simulation(DES), and the transient iteration was solved by the dual-time step lower-upper symmetric Gauss-Seidel(LU-SGS) meth... The influence of ribs on the train aerodynamic performance was computed using detached eddy simulation(DES), and the transient iteration was solved by the dual-time step lower-upper symmetric Gauss-Seidel(LU-SGS) method. The results show that the ribs installed on the roof have a great effect on the train aerodynamic performance. Compared with trains without ribs, the lift force coefficient of the train with convex ribs changes from negative to positive, while the side force coefficient increases by 110%and 88%, respectively. Due to the combined effect of the lift force and side force, the overturning moment of the train with convex ribs and cutting ribs increases by 140% and 106%, respectively. There is larger negative pressure on the roof of the train without ribs than that with ribs. The ribs on the train would disturb the flow structure and contribute to the air separation, so the separation starts from the roof, while there is no air separation on the roof of the train without ribs. The ribs can also slow down the flow speed above the roof and make the air easily sucked back to the train surface. The vortices at the leeward side of the train without ribs are small and messy compared with those of the train with convex or cutting ribs. 展开更多
关键词 TRAIN RIB detached eddy simulation(DES) aerodynamic performance CROSSWIND
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Numerical study of the influence of dome shape on the unsteady aerodynamic performance of a high-speed train's pantograph subjected to crosswind 被引量:1
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作者 Xiaofang Li Dan Zhou +1 位作者 Lirong Jia Mingzhi Yang 《Journal of Traffic and Transportation Engineering(English Edition)》 EI CSCD 2023年第1期13-30,共18页
This study aims to investigate the unsteady aerodynamic performance of a high-speed train’s pantograph with respect to two different dome shapes and without dome under a20°yaw angle using a delayed detached eddy... This study aims to investigate the unsteady aerodynamic performance of a high-speed train’s pantograph with respect to two different dome shapes and without dome under a20°yaw angle using a delayed detached eddy simulation method.Further,the influence of the dome shape on the simulation results is determined.The accuracy of the numerical method was validated by comparing a few of the numerical results with the wind tunnel test results,and high consistency was observed.An analysis of aerodynamic forces and flow structures around the pantograph was performed.The dome had significant influence on velocity field distribution surrounding the pantograph,particularly in the wake of flow region.Compared with the case where the dome was absent,vortex intensity around the pantograph increased after installing the dome.The existence of the bathtub-type dome resulted in greater flow field disturbance and vortex strength than the baffle-type dome.Moreover,the dome considerably affected time-averaged aerodynamic coefficients and their fluctuations,especially the bathtub-type dome.Additionally,the power spectral density of the unsteady aerodynamic coefficient of each pantograph component exhibited significant peaks and typical broadband distribution characteristics. 展开更多
关键词 High-speed train CROSSWIND PANTOGRAPH DOME Unsteady aerodynamic performance
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Uncertainty analysis of measured geometric variations in turbine blades and impact on aerodynamic performance
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作者 Xiaojing WANG Pengcheng DU +2 位作者 Lichao YAO Zhengping ZOU Fei ZENG 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2023年第6期140-160,共21页
Inevitable geometric variations significantly affect the performance of turbines or even that of entire engines;thus,it is necessary to determine their actual characteristics and accurately estimate their impact on pe... Inevitable geometric variations significantly affect the performance of turbines or even that of entire engines;thus,it is necessary to determine their actual characteristics and accurately estimate their impact on performance.In this study,based on 1781 measured profiles of a typical turbine blade,the statistical characteristics of the geometric variations and the uncertainty impact are analyzed,and some commonly used uncertainty modelling methods based on Principal-Component Analysis(PCA)are verified.The geometric variations are found to be evident,asymmetric,and non-uniform,and the non-normality of the random distributions is non-negligible.The performance is notably affected,which is manifested as an overall offset,a notable scattering,and significant deterioration in several extreme cases.Additionally,it is demonstrated that the PCA reconstruction model is effective in characterizing major uncertainty characteristics of the geometric variations and their impact on the performance with almost the first 10 PCA modes.Based on a reasonable profile error and mean geometric deviation,the Gaussian assumption and stochasticprocess-based model are also found to be effective in predicting the mean values and standard deviations of the performance variations.However,they fail to predict the probability of some extreme cases with high loss.Finally,a Chi-square-based correction model is proposed to compensate for this deficiency.The present work can provide a useful reference for uncertainty analysis of the impact of geometric variations,and the corresponding uncertainty design of turbine blades. 展开更多
关键词 aerodynamic performance Measured geometric variations Principal-component analysis Turbine blade Uncertainty analysis
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EXPERIMENTAL RESEARCH ON AERODYNAMIC PERFORMANCE AND EXIT FLOW FIELD OF LOW PRESSURE AXIAL FLOW FAN WITH CIRCUMFERENTIAL SKEWED BLADES 被引量:18
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作者 LI Yang OUYANG Hua DU Zhao-hui 《Journal of Hydrodynamics》 SCIE EI CSCD 2007年第5期579-586,共8页
In this article, the low pressure axial flow fan with circumferential skewed rotor blade, including the radial blade, the forward-skewed blade and the backward-skewed blade, was studied with experimental methods. The ... In this article, the low pressure axial flow fan with circumferential skewed rotor blade, including the radial blade, the forward-skewed blade and the backward-skewed blade, was studied with experimental methods. The aerodynamic performance of the rotors was measured. At the design condition at outlet of the rotors, detailed flow measurements were performed with a five-hole probe and a Hot-Wire Anemometer (HWA). The results show that compared to the radial rotor, the forward-skewed rotor demonstrates a wider Stable Operating Range (SOR), is able to reduce the total pressure loss in the hub region and make main loading of blade accumulating in the mid-span region. There is a wider wake in the upper mid-span region of the forward-skewed rotor. Compared to the radial rotor, in the backward-skewed rotor there is higher total pressure loss near the hub and shroud regions and lower loss in the mid-span region. In addition, the velocity deficit in the wake is lower at mid-span of the backward-skewed rotor than the forward-skewed rotor. 展开更多
关键词 low pressure axial flow fan circumferential skewed blade aerodynamic performance exit flow field StableOperating Range (SOR)
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Influence of leading edge with real manufacturing error on aerodynamic performance of high subsonic compressor cascades 被引量:8
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作者 Chi MA Limin GAO +2 位作者 Haohao WANG Ruiyu LI Baohai WU 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2021年第6期220-232,共13页
To investigate the influence of real leading-edge manufacturing error on aerodynamic performance of high subsonic compressor blades,a family of leading-edge manufacturing error data were obtained from measured compres... To investigate the influence of real leading-edge manufacturing error on aerodynamic performance of high subsonic compressor blades,a family of leading-edge manufacturing error data were obtained from measured compressor cascades.Considering the limited samples,the leadingedge angle and leading-edge radius distribution forms were evaluated by Shapiro-Wilk test and quantile–quantile plot.Their statistical characteristics provided can be introduced to later related researches.The parameterization design method B-spline and Bezier are adopted to create geometry models with manufacturing error based on leading-edge angle and leading-edge radius.The influence of real manufacturing error is quantified and analyzed by self-developed non-intrusive polynomial chaos and Sobol’indices.The mechanism of leading-edge manufacturing error on aerodynamic performance is discussed.The results show that the total pressure loss coefficient is sensitive to the leading-edge manufacturing error compared with the static pressure ratio,especially at high incidence.Specifically,manufacturing error of the leading edge will influence the local flow acceleration and subsequently cause fluctuation of the downstream flow.The aerodynamic performance is sensitive to the manufacturing error of leading-edge radius at the design and negative incidences,while it is sensitive to the manufacturing error of leading-edge angle under the operation conditions with high incidences. 展开更多
关键词 aerodynamic performance Compressor cascade Limited measurement data Manufacturing error Uncertainty analysis
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Aerodynamic performance enhancement forflapping airfoils by co-flow jet 被引量:7
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作者 Tao WU Bifeng SONG +2 位作者 Wenping SONG Wenqing YANG Zhonghua HAN 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2020年第10期2535-2554,共20页
Introducing active flow control into the design of flapping wing is an effective way to enhance its aerodynamic performance.In this paper,a novel active flow control technology called Co-Flow Jet(CFJ)is applied to fla... Introducing active flow control into the design of flapping wing is an effective way to enhance its aerodynamic performance.In this paper,a novel active flow control technology called Co-Flow Jet(CFJ)is applied to flapping airfoils.The effect of CFJ on aerodynamic performance of flapping airfoils at low Reynolds number is numerically investigated using Unsteady Reynolds Averaged Navier-Stokes(URANS)simulation with Spalart-Allmaras(SA)turbulence model.Numerical methods are validated by a NACA6415-based CFJ airfoil case and a S809 pitching airfoil case.Then NACA6415 baseline airfoil and NACA6415-based CFJ airfoil with jet-off and jet-on are simulated in flapping motion,with Reynolds number 70,000 and reduced frequency 0.2.As a result,CFJ airfoils with jet-on generally have better lift and thrust characteristics than baseline airfoils and jet-off airfoil when Cμgreater than 0.04,which results from the CFJ effect of reducing flow separation by injecting high-energy fluid into boundary layer.Besides,typical kinematic and geometric parameters,including the reduced frequency and the positions of the suction and injection slot,are systematically studied to figure out their influence on aerodynamic performance of the CFJ airfoil.And a variable Cμjet control strategy is proposed to further improve effective propulsive efficiency.Compared with using constant Cμ,an increase of effective propulsive efficiency by22.6%has been achieved by using prescribed variable CμNACA6415-based CFJ airfoil at frequency 0.2.This study may provide some guidance to performance enhancement for Flapping wing Micro Air Vehicles(FMAV). 展开更多
关键词 aerodynamic performance Co-flow jet Flapping airfoils Flow control Propulsive efficiency
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Aerodynamic performance enhancement of co-flow jet airfoil with simple high-lift device 被引量:3
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作者 Haolin ZHI Zhenhao ZHU +2 位作者 Yujin LU Shuanghou DENG Tianhang XIAO 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2021年第9期143-155,共13页
The present study performed a numerical investigation to explore the performance enhancement of a co-flow jet(CFJ)airfoil with simple high-lift device configuration,with a specific goal to examine the feasibility and ... The present study performed a numerical investigation to explore the performance enhancement of a co-flow jet(CFJ)airfoil with simple high-lift device configuration,with a specific goal to examine the feasibility and capability of the proposed configuration for low-speed take-off and landing.Computations have been accomplished by an in-house-programmed Reynoldsaveraged Navier-Stokes solver enclosed by k-ωshear stress transport turbulence model.Three crucial geometric parameters,viz.,injection slot location,suction slot location and its angle were selected for the sake of revealing their effects on aerodynamic lift,drag,power consumption and equivalent lift-to-drag ratio.Results show that using simple high-lift devices on CFJ airfoil can significantly augment the aerodynamic associated lift and efficiency which evidences the feasibility of CFJ for short take-off and landing with small angle of attack.The injection and suction slot locations are more influential with respect to the aerodynamic performance of CFJ airfoil compared with the suction slot angle.The injection location is preferable to be located in the downstream of the pressure suction peak on leading edge to reduce the power expenditure of the pumping system for a relative higher equivalent lift-to-drag ratio.Another concluded criterion is that the suction slot should be oriented on the trailing edge flap for achieving more aerodynamic gain,meanwhile,carefully selecting this location is crucial in determining the aerodynamic enhancement of CFJ airfoil with deflected flaps. 展开更多
关键词 AIRFOIL Co-flow jet Flow control aerodynamic performance enhancement Simple high-lift device
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Effects of surface roughness on the aerodynamic performance of a high subsonic compressor airfoil at low Reynolds number 被引量:2
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作者 Mingyang WANG Chengwu YANG +3 位作者 Ziliang LI Shengfeng ZHAO Yanfeng ZHANG Xin’gen LU 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2021年第3期71-81,共11页
The aerodynamic performance of compressor airfoil is significantly affected by the surface roughness at low Reynolds number(Re).In the present study,numerical simulations have been conducted to investigate the impact ... The aerodynamic performance of compressor airfoil is significantly affected by the surface roughness at low Reynolds number(Re).In the present study,numerical simulations have been conducted to investigate the impact of surface roughness on the profile loss of a high subsonic compressor airfoil at Re=1.5×10^(5).Four roughness locations,covering 10%,30%,50%and 100%of the suction surface from the leading edge and seven roughness magnitudes(Ra)ranging from 52 to525 lm were selected.Results showed that the surface roughness mainly determined the loss generation process by influencing the structure of the Laminar Separation Bubble(LSB)and the turbulence level near the wall.For all the roughness locations,the variation trend for the profile loss with the roughness magnitude was similar.In the transitionally rough region,the negative displacement effect of the LSB was suppressed with the increase of roughness magnitude,leading to a maximum decrease of 14.6%,16.04%,16.45%and 10.20%in the profile loss at Ra=157 lm for the four roughness locations,respectively.However,with a further increase of the roughness magnitude in the fully rough region,the stronger turbulent dissipation enhanced the growth rate of the turbulent boundary layer and increased the profile loss instead.By comparison,the leading edge roughness played a dominant role in the boundary layer development and performance variation.To take fully advantage of the surface roughness reducing profile loss at low Re,the effects of roughness on suppressing LSB and inducing strong turbulent dissipation should be balanced effectively. 展开更多
关键词 aerodynamic performance Compressor airfoil Low Reynolds number Separation bubble Surface roughness Viscous dissipation
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Aerodynamic performance of owl-like airfoil undergoing bio-inspired flapping kinematics 被引量:2
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作者 Xinyu LANG Bifeng SONG +1 位作者 Wenqing YANG Wenping SONG 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2021年第5期239-252,共14页
Natural flyers have extraordinary flight skills and their prominent aerodynamic performance has attracted a lot of attention.However,the aerodynamic mechanism of birds’flapping wing kinematics still lacks in-depth un... Natural flyers have extraordinary flight skills and their prominent aerodynamic performance has attracted a lot of attention.However,the aerodynamic mechanism of birds’flapping wing kinematics still lacks in-depth understanding.In this paper,the aerodynamic performance of owl-like airfoil undergoing bio-inspired flapping kinematics extracted from a free-flying owl wing has been numerically investigated.The overset mesh technique is used to deal with the large range movements of flapping airfoils.The bio-inspired kinematics consist of plunging and pitching movement.A pure sinusoidal motion and a defined motion composed of plunging of sinusoidal motion and pitching of the bio-inspired kinematics are selected for comparison.The other two NACA airfoils are also selected to figure out the advantages of the owl-like airfoil.It is found that the cambered owl-like airfoil can enhance lift during the downstroke.The bio-inspired kinematics have an obvious advantage in lift generation with a presence of higher peak lift and positive lift over a wider proportion of the flapping cycle.Meanwhile,the bio-inspired motion is more economical for a lower power consumption compared with the sinusoidal motion.The sinusoidal flapping motion is better for thrust generation for a higher peak thrust value in both upstroke and downstroke,while the bio-inspired kinematics mainly generate thrust during the downstroke but produce more drag during the upstroke.The defined motion has similar lift performance with the bio-inspired kinematics,while it consumes more energy and generates less thrust.The unsteady flow field around airfoils is also analyzed to explain the corresponding phenomenon.The research in this paper is helpful to understand the flight mechanism of birds and to design a micro air vehicle with higher performance. 展开更多
关键词 aerodynamic performance Bio-inspired kinematics Flapping airfoils Low Reynolds number Micro aerial vehicles
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Effect of Gurney flap on flow separation and aerodynamic performance of an airfoil under rain and icing conditions 被引量:1
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作者 Hossein Fatahian Hesamoddin Salarian +1 位作者 Majid Eshagh Nimvari Jahanfar Khaleghinia 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2020年第3期659-677,共19页
In the present study,special attention is paid to numerically investigate the aerodynamic performance of the NACA 0012 airfoil under rain and icing conditions with the aim to better understand the severe aerodynamic p... In the present study,special attention is paid to numerically investigate the aerodynamic performance of the NACA 0012 airfoil under rain and icing conditions with the aim to better understand the severe aerodynamic performance penalties of aircraft in flight.Furthermore,in order to control the flow separation and improve the aerodynamic performance of the airfoil under critical atmospheric conditions,the Gurney flap with different heights is attached to the trailing edge of the airfoil.The simulation is done at a Reynolds number of 3.1 × 105 under different atmospheric conditions including dry,rain,icing and coupling of rain and icing conditions.A two-way momentum coupled Eulerian-Lagrangian multiphase method is used to simulate the process of water film layer formed on the airfoil surface due to rainfall.According to the results,accumulation of water due to rainfall and ice accretion on the airfoil surface inevitably provides notable negative effects on the aerodynamic performance of the airfoil.It is concluded that icing induces a higher aerodynamic degradation than rain due to very intensive ice accretion.The Gurney flap as a passive flow control method with a favorable height for each condition is very beneficial.The maximum increment of the lift-to-drag ratio is achieved by Gurney Hap with a height of 0.01 of airfoil chord length for dry and rain conditions and 0.02 of airfoil chord length for icing and coupling of rain and icing conditions,respectively. 展开更多
关键词 AIRFOIL Flow separation aerodynamic performance Gurney flap Rain and icing Multiphase method
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Effects of Chordwise Flexibility on the Aerodynamic Performance of a 3D Flapping Wing 被引量:1
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作者 Xin Cheng Shilong Lan 《Journal of Bionic Engineering》 SCIE EI CSCD 2015年第3期432-442,共11页
Previous studies on chordwise flexibility of flexible wings generally relied on simplified two-dimensional (2D) models. In the present study, we constructed a simplified three-dimensional (3D) model and identified... Previous studies on chordwise flexibility of flexible wings generally relied on simplified two-dimensional (2D) models. In the present study, we constructed a simplified three-dimensional (3D) model and identified the role of the chordwise flexibility in full flapping motion. This paper includes two parts, the first part discusses the aerodynamic effects of the chordwise flexibility in a typical hovering-flight case; the second part introduces a parametric study of four key parameters. The primary findings are as follows. Flexibility generally degrades the lift performance of the flexible wings. However, in two special cases, i.e. when stroke amplitude is low or pitch rotation is delayed, the flexible wings outperform their rigid counterparts in lift generation. Moreover, flexibility reduces the power consumption of the flexible wings. A wing with small flexibility generally achieves a marginally higher flapping efficiency than its rigid counterpart. Furthermore, reducing stroke amplitude can effectively improve the lift performance of the very flexible wings. Aerodynamic performances of the flexible wings are not as sensitive as the rigid wing to phase difference and mid-stroke angle of attaek. The effects of Re are the same for the flexible and rigid wings. 展开更多
关键词 flapping wing chordwise flexibility aerodynamic performances parametric study
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Aerodynamic Performance Improvement of a Highly Loaded Compressor Airfoil with Coanda Jet Flap 被引量:1
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作者 ZHANG Jian DU Juan +3 位作者 ZHANG Min CHEN Ze ZHANG Hongwu NIE Chaoqun 《Journal of Thermal Science》 SCIE EI CAS CSCD 2022年第1期151-162,共12页
Coanda jet flap is an effective flow control technique,which offers pressurized high streamwise velocity to eliminate the boundary layer flow separation and increase the aerodynamic loading of compressor blades.Tradit... Coanda jet flap is an effective flow control technique,which offers pressurized high streamwise velocity to eliminate the boundary layer flow separation and increase the aerodynamic loading of compressor blades.Traditionally,there is only single-jet flap on the blade suction side.A novel Coanda double-jet flap configuration combining the front-jet slot near the blade leading edge and the rear-jet slot near the blade trailing edge is proposed and investigated in this paper.The reference highly loaded compressor profile is the Zierke&Deutsch double-circular-arc airfoil with the diffusion factor of 0.66.Firstly,three types of Coanda jet flap configurations including front-jet,rear-jet and the novel double-jet flaps are designed based on the 2D flow fields in the highly loaded compressor blade passage.The Back Propagation Neural Network(BPNN)combined with the genetic algorithm(GA)is adopted to obtain the optimal geometry for each type of Coanda jet flap configuration.Numerical simulations are then performed to understand the effects of the three optimal Coanda jet flaps on the compressor airfoil performance.Results indicate all the three types of Coanda jet flaps effectively improve the aerodynamic performance of the highly loaded airfoil,and the Coanda double-jet flap behaves best in controlling the boundary layer flow separation.At the inlet flow condition with incidence angle of 5°,the total pressure loss coefficient is reduced by 52.5%and the static pressure rise coefficient is increased by 25.7%with Coanda double-jet flap when the normalized jet mass flow ratio of the front jet and the rear jet is equal to 1.5%and 0.5%,respectively.The impacts of geometric parameters and jet mass flow ratios on the airfoil aerodynamic performance are further analyzed.It is observed that the geometric design parameters of Coanda double-jet flap determine airfoil thickness and jet slot position,which plays the key role in supressing flow separation on the airfoil suction side.Furthermore,there exists an optimal combination of front-jet and rear-jet mass flow ratios to achieve the minimum flow loss at each incidence angle of incoming flow.These results indicate that Coanda double-jet flap combining the adjust of jet mass flow rate varying with the incidence angle of incoming flow would be a promising adaptive flow control technique. 展开更多
关键词 Coanda jet flap high loaded compressor active flow control aerodynamic performance
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The typhoon effect on the aerodynamic performance of a floating offshore wind turbine 被引量:1
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作者 Zhe Ma Wei Li +1 位作者 Nianxin Ren Jinping Ou 《Journal of Ocean Engineering and Science》 SCIE 2017年第4期279-287,共9页
The wind energy resource is considerably rich in the deep water of China South Sea,where wind farms have to face the challenge of extreme typhoon events.In this work,the typhoon effect on the aerodynamic performance o... The wind energy resource is considerably rich in the deep water of China South Sea,where wind farms have to face the challenge of extreme typhoon events.In this work,the typhoon effect on the aerodynamic performance of the 5MW OC3-Hywind floating offshore wind turbine(FOWT)system has been investigated,based on the Aero-Hydro-Servo-Elastic FAST code.First,considering the full field observation data of typhoon“Damrey”is a long duration process with significant turbulence and high wind speed,so one 3-h representative truncated typhoon wind speed time history has been selected.Second,the effects of both the(variable-speed and collective-pitch)control system of NREL 5 MW wind turbine and the motion of the floating platform on the blade aerodynamic performance of the FOWT system during the representative typhoon time history has been investigated,based on blade element momentum(BEM)theory(coupled with potential theory for the calculation of the hydrodynamic loads of the Spar platform).Finally,the effects of different wind turbine control strategies,control parameter(KP-KI)combinations,wave heights and parked modes on the rotor aerodynamic responses of the FOWT system have been clarified.The extreme typhoon event can result in considerably large extreme responses of the rotor thrust and the generated power due to the possible blade pitch angle error phenomenon.One active-parked strategy has been proposed for reducing the maximum aerodynamic responses of the FOWT system during extreme typhoon events. 展开更多
关键词 TYPHOON Floating offshore wind turbine aerodynamic performance Control system FAST
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Effects of airfoil on aerodynamic performance of flapping wing 被引量:1
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作者 Min Zhao Yao Zou +1 位作者 Qiang Fu Wei He 《Biomimetic Intelligence & Robotics》 2021年第1期31-35,共5页
Flapping-wing aircraft(FWA)operates in a flight mode that mimics natural flyers,such as birds,bats and insects.For large scale bird-inspired flapping wings aircraft,the design of airfoil parameters is crucial to impro... Flapping-wing aircraft(FWA)operates in a flight mode that mimics natural flyers,such as birds,bats and insects.For large scale bird-inspired flapping wings aircraft,the design of airfoil parameters is crucial to improving the aerodynamic performance.In order to study the effect of camber on the aerodynamic characteristics,we developed four different airfoils with a chord length of 12 cm.The cambers of airfoils are respectively 30 mm,25 mm,20 mm and 15 mm.A numerical investigation into the effects of camber on aerodynamic performance is carried out through COMSOL Multiphysics software using Fluid–Structure Interaction(FSI)module.In this work,the fluid–structure module employs the Navier–Stokes equations coupled with a solid stress–strain physics module and a moving mesh module.The three-dimensional(3D)flapping wing computational models with different cambers are built.The results show that certain camber of airfoil can improve the aerodynamic characteristics of flapping wing. 展开更多
关键词 aerodynamic performance AIRFOIL CAMBER FIS COMSOL
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A Biomimetic Rotor-configuration Design for Optimal Aerodynamic Performance in Quadrotor Drone
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作者 Yi Li Koichi Yonezawa +1 位作者 Ru Xu Hao Liu 《Journal of Bionic Engineering》 SCIE EI CSCD 2021年第4期824-839,共16页
Motivated by optimal combination of paired wings configuration and troke-plane inclination in biological flapping flights that can achieve high aerodynamic performance,we propose a biomimetic rotor-configuration desig... Motivated by optimal combination of paired wings configuration and troke-plane inclination in biological flapping flights that can achieve high aerodynamic performance,we propose a biomimetic rotor-configuration design to explore optimal aerodynamic performance in multirotor drones.While aerodynamic interactions among propellers in multirotor Unmanned Aerial Vehicles(UAVs)play a crucial role in lift force production and Figure of Merit(FM)efficiency,the rotor-configuration effect remains poorly understood.Here we address a Computational Fluid Dynamics(CFD)-based study on optimal aerodynamic performance of the rotor-configuration in hovering quadrotor drones with a specific focus on the aerodynamic effects of tip distance,height difference and tilt angle of propellers.Our results indicate that the tip distance-induced interactions can most alter lift force production and hence lead to remarked improvement in FM,and the height difference also plays a key role in improving aerodynamic performance,while the tilt angle effect is less important.Furthermore,we carried out an extensive analysis to explore the optimal aerodynamic performance of the rotor-configuration over a broad parameter space,by combining the CFD-based simulations and a novel surrogate model.We find that a rotor-configuration with a large tip distance and some height difference with zero tilt angle is capable of optimizing both lift force production and FM,which could offer a novel optimal design as well as maneuver strategy for multirotor UAVs. 展开更多
关键词 bioinspiration optimal quadrotor configuration aerodynamic interactions aerodynamic performance CFD surrogate modeling
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Simulation on effect of throat contraction ratio and strake stagger angle on flow field and aerodynamic performance of scrampressor
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作者 YANG Ling ZHONG Jing-jun HAN Ji-ang 《航空动力学报》 EI CAS CSCD 北大核心 2017年第5期1183-1194,共12页
The design methods of typical supersonic aircraft intakes and shock wave compression technology have been applied to ram-rotor,an attractive compression system.A ram-rotor is of a typical structure including the compr... The design methods of typical supersonic aircraft intakes and shock wave compression technology have been applied to ram-rotor,an attractive compression system.A ram-rotor is of a typical structure including the compression ramp,the throat and the subsonic diffuser;a scrampressor is similar to ram-rotor,the only difference is that scrampressor has no subsonic diffuser.The work was the continuation of the preparatory work.In order to further study the effect of throat contraction ratio and strake stagger angle on the flow field and performance of a scrampressor,the flow field of a scrampressor with a three-dimensional flow path was numerically simulated with different throat contraction ratios and strake stagger angles.Simulated results indicated that the optional aerodynamic performance of a scrampressor could be achieved with an adiabatic efficiency of 0.8413atotal pressure recovery coefficient of 0.8446,a total pressure ratio of 7.14 and a static pressure ratio of 5.17for a throat contraction ratio of 0.6 and a strake stagger angle of 12°.It was therefore concluded that an appropriate decrease in throat contraction ratio and an increase in strake stagger angle could help the comprehensive improvement of a scrampressor in performance. 展开更多
关键词 scrampressor flow field aerodynamic performance throat contraction ratio strake stagger angle
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Coupled Aerodynamic and Hydrodynamic Analysis of Floating Offshore Wind Turbine Using CFD Method 被引量:1
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作者 Wu Jun Meng Long +1 位作者 Zhao Yongsheng He Yanping 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2016年第1期80-87,共8页
To simulate floating offshore wind turbine(FOWT)in coupled wind-wave domain via CFD method,the NREL 5MW wind turbine supported by the OC3-Hywind Spar platform is modeled in the STAR-CCM+ software.Based on the Reynolds... To simulate floating offshore wind turbine(FOWT)in coupled wind-wave domain via CFD method,the NREL 5MW wind turbine supported by the OC3-Hywind Spar platform is modeled in the STAR-CCM+ software.Based on the Reynolds-averaged Navier-Stokes(RANS)equations and re-normalisation group(RNG)k-εturbulence model,the rotor aerodynamic simulation for wind turbine is conducted.Numerical results agree well with the NREL data.Taking advantage with the volume of fluid(VOF)method and dynamic fluid body interaction(DFBI)technology,the dynamic responses of the floating system with mooring lines are simulated under the coupled wind-wave sea condition.The free-decay tests for rigid-body degrees of freedom(DOFs)in still water and hydrodynamic tests in a regular wave are performed to validate the numerical model by comparing its result with the results simulated by FAST.Finally,the simulations of the overall FOWT system in the coupled wind-wave flow field are carried out.The relationship between the power output and dynamic motion responses of the platform is investigated.The numerical results show that the dynamic response of wind turbine performance and platform motions all vary in the same frequency as the inlet wave.During platform motion,the power output of wind turbine is more sensitive than the thrust force.This study may provide some reference for further research in the coupled aero-hydro simulation of FOWT. 展开更多
关键词 floating offshore wind turbine(FOWT) computational fluid dynamics(CFD) aerodynamic perform ance dynamic fluid body interaction
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