Multi-point airfoil optimization for axial-flow fan

Airfoil is the element of fan blade design. It is strongly anticipated to design a fan of ave- raged high performance over a wide operation range. Multi-point optimization design of airfoil for axial flow fan was proposed over specific operation range. Weighted objective function of airfoil lift-drag ratio was constructed for several operation points around the designing one. Airfoil was defined by parametric B-spline curve of limited shape controlling points. Results show that normal standard airfoils have remained spaces to be optimized under specific operation conditions. Airfoil performance is sensitive to flow′s Reynolds number and cascade solidity. Predicting flow transition along airfoil profile is essential to search for optimized one. Optimized airfoil of wide operation range is possible to obtain with prescribed fitness function. Obtainments of multi-point optimization may be relatively lower at design point, but positive obtainments are achieved at off-design ones. Resulted airfoil is specially suitable for axial flow fans operating frequently at off-design point such as air condition coolers.

Debris Fan Produced by Failure of Canyon-Blocking Pyroclastic Flows

Ash-rich pyroclastic flows from the cataclysmic eruption of Mount Mazama (~7700 yr. B. P.), Cascade volcanic arc, Oregon, entered and blocked the narrow, bedrock-lined canyon of the Williamson River approximately 35 to 44 km from the source volcano. The blockage impounded a body of water which then released producing four stratigraphic units in the downstream debris fan. The four stratigraphic units are a boulder core comprised of locally sourced bedrock boulders and three sand-rich units including a fine-grained sand unit, a sandy pumice gravel (±basalt/hydrovolcanic tuff) unit, and a pumice pebble-bearing, crystal-rich sand unit. Hand-drilled auger holes up to ~1.6 m deep were used to obtain samples of the sand-rich units. Units were delimited using surface and down-hole observations, composition and texture, estimated density, statistical parameters of grain size, and vertical and lateral distribution of properties. Overtopping followed by rapid incision into the ash-rich pyroclastic flows progressively cleared the canyon, but a bedrock knickpoint near the head of the canyon limited the volume of debris available for transport to about 0.04 km3 to 0.08 km3. Co-deposition of bedrock boulders and lithic-rich sand was followed by rapid deposition with minimal reworking of remobilized pyroclastics. Continued draining of the impounded lake sent hyperconcentrated flows onto the debris fan depositing pumice-rich gravels that graded upward to crystal-rich sands.

广义的Ky Fan定理

矩阵行列式是矩阵分析学中一个很重要的分支,利用矩阵外代数,可以把行列式的计算转换成矩阵的迹算子。首先,从典型的Ky Fan定理出发,给出了该定理的一个等价形式,并且利用Brunn-Minkowski不等式给出了定理的证明。其次,利用凸函数的性质,得到了Ky Fan定理的一个更一般的表示形式。

双星图的LI矩阵的Ky Fan k-范数

树是连通的无圈图,研究树的拉普拉斯矩阵具有重要的图论和实际意义.设G是一个有n个点和m个边的图,A(G)和D(G)分别是图G的邻接矩阵和对角度矩阵,那么G的拉普拉斯矩阵定义为L(G)=D(G)-A(G).LI矩阵定义为LI(G)=L(G)-(2m/n)I_(n),其中I_(n)是单位矩阵.图的LI矩阵的Ky Fan k-范数代表了拉普拉斯特征值和拉普拉斯特征值平均值之间距离的有序和.研究了双星图的LI矩阵的Ky Fan k-范数,证明了双星图的LI矩阵的Ky Fan k-范数满足文献[6]中提出的猜想.

Effects of desert plant communities on soil enzyme activities and soil organic carbon in the proluvial fan in the eastern foothills of the Helan Mountain in Ningxia,China

It is of great significance to study the effects of desert plants on soil enzyme activities and soil organic carbon(SOC)for maintaining the stability of the desert ecosystem.In this study,we studied the responses of soil enzyme activities and SOC fractions(particulate organic carbon(POC)and mineral-associated organic carbon(MAOC))to five typical desert plant communities(Convolvulus tragacanthoides,Ephedra rhytidosperma,Stipa breviflora,Stipa tianschanica var.gobica,and Salsola laricifolia communities)in the proluvial fan in the eastern foothills of the Helan Mountain in Ningxia Hui Autonomous Region,China.We recorded the plant community information mainly including the plant coverage and herb and shrub species,and obtained the aboveground biomass and plant species diversity through sample surveys in late July 2023.Soil samples were also collected at depths of 0–10 cm(topsoil)and 10–20 cm(subsoil)to determine the soil physicochemical properties and enzyme activities.The results showed that the plant coverage and aboveground biomass of S.laricifolia community were significantly higher than those of C.tragacanthoides,S.breviflora,and S.tianschanica var.gobica communities(P<0.05).Soil enzyme activities varied among different plant communities.In the topsoil,the enzyme activities of alkaline phosphatase(ALP)andβ-1,4-glucosidas(βG)were significantly higher in E.rhytidosperma and S.tianschanica var.gobica communities than in other plant communities(P<0.05).The topsoil had higher POC and MAOC contents than the subsoil.Specifically,the content of POC in the topsoil was 18.17%–42.73%higher than that in the subsoil.The structural equation model(SEM)indicated that plant species diversity,soil pH,and soil water content(SWC)were the main factors influencing POC and MAOC.The soil pH inhibited the formation of POC and promoted the formation of MAOC.Conversely,SWC stimulated POC production and hindered MAOC formation.Our study aimed to gain insight into the effects of desert plant communities on soil enzyme activities and SOC fractions,as well as the drivers of SOC fractions in the proluvial fan in the eastern foothills of the Helan Mountain and other desert ecosystems.

Temperature-Based Fan Speed Optimization Strategy

As energy efficiency and indoor comfort increasingly become key standards in modern residential and office environments,research on intelligent fan speed control systems has become particularly important.This study aims to develop a temperature-feedback-based fan speed optimization strategy to achieve higher energy efficiency and user comfort.Firstly,by analyzing existing fan speed control technologies,their main limitations are identified,such as the inability to achieve smooth speed transitions.To address this issue,a BP-PID speed control algorithm is designed,which dynamically adjusts fan speed based on indoor temperature changes.Experimental validation demonstrates that the designed system can achieve smooth speed transitions compared to traditional fan systems while maintaining stable indoor temperatures.Furthermore,the real-time responsiveness of the system is crucial for enhancing user comfort.Our research not only demonstrates the feasibility of temperature-based fan speed optimization strategies in both theory and practice but also provides valuable insights for energy management in future smart home environments.Ultimately,this research outcome will facilitate the development of smart home systems and have a positive impact on environmental sustainability.

参数向量Ky Fan不等式与对偶问题解映射Lipschitz连续性最优条件

在赋范线性空间中研究参数向量Ky Fan不等式与对偶问题解映射的Lipschitz连续性。提出了参数向量Ky Fan不等式与对偶问题及其有效解的概念,引入了向量函数伪单调性和强拟凸(凹)性,借助分析方法获得了参数向量Ky Fan不等式与对偶问题解映射的Lipschitz连续性最优条件,并举例加以说明。

Analysis of Tonal Noise Generating Mechanisms in Low-Speed Axial-Flow Fans

The present paper reports a comparison of experimental SPL spectral data related to the tonal noise generated by axial-flow fans.A nine blade rotor has been operated at free discharge conditions and in four geometrical configurations in which different kinds of tonal noise generating mechanisms are present:large-scale inlet turbulent structures,tip-gap flow,turbulent wakes,and rotor-stator interaction.The measurements have been taken in a hemi-anechoic chamber at constant rotational speed and,in order to vary the acoustic source strength,during low angular acceleration,linear speed ramps.In order to avoid erroneous quantitative evaluations if the acoustic propagation effects are not considered,the acoustic response functions of the different test configurations have been computed by means of the spectral decomposition method.Then,the properties of the tonal noise generating mechanisms have been studied.To this aim,the constant-Strouhal number SPL,obtained by means of measurements taken during the speed ramps,have been compared with the propagation function.Finally,the analysis of the phase of the acoustic pressure has allowed to distinguish between random and deterministic tonal noise generating mechanisms and to collect information about the presence of important propagation effects.

Design of Off-statistics Axial-flow Fans by Means of Vortex Law Optimization

Off-statistics input data sets are common in axial-flow fans design and may easily result in some violation of the requirements of a good aerodynamic blade design.In order to circumvent this problem,in the present paper,a solution to the radial equilibrium equation is found which minimizes the outlet kinetic energy and fulfills the aerodynamic constraints,thus ensuring that the resulting blade has acceptable aerodynamic performance.The presented method is based on the optimization of a three-parameters vortex law and of the meridional channel size.The aerodynamic quantities to be employed as constraints are individuated and their suitable ranges of variation are proposed.The method is validated by means of a design with critical input data values and CFD analysis.Then,by means of systematic computations with different input data sets,some correlations and charts are obtained which are analogous to classic correlations based on statistical investigations on existing machines.Such new correlations help size a fan of given characteristics as well as study the feasibility of a given design.

OPTIMIZATION DESIGN OF GAS-PARTICLE TWO PHASE AXIAL-FLOW FAN

Based on the shaping theory of writhed blade in streamline design, the geometric shape of blade is designed and then computational formulas for the dynamic design of the fan with writhed blades in gas-particle two-phase axial-flow are derived with the two-phase continuum coupling model. Concurrently, the correlation between the structure of impeller and flow-field dynamic functional parameters is presented. Further, the software for the optimization design of the gas-particle two-phase axial-flow fan with writhed blades is obtained. By means of the available software, a sample fan is formed, and its all dynamic characteristic curves and its geometric shape are presented. Finally, the conclusion on the effect of particles on fan running is reached quantitatively and qualitatively, as is expected in the fan industry.

Zhu Fan Zhi and the Maritime Road of Aromatic Medicine in the Song Dynasty

Zhao Rukuo's Zhu Fan Zhi in the Southern Song dynasty was the first book in the history of China to systematically describe the “Maritime Silk Road”, recording the geography, products, customs, trade, etc. of more than 50 foreign countries and regions. The book included a large amount of medical literature, introducing medical customs and the production of drugs in various places, as well as the efficacy of some medicine. These materials are of unique value for understanding the medicine trade in the Song dynasty, and even the medical culture along the “Maritime Road of Aromatic Medicine”.

Numerical Study on the Duct Noise Control of Single-Stage Axial Flow Fan with Wave Leading Edge Stator Blade Configurations

This study focuses on a single-stage axial flow fan, investigating the effect of three kinds of wave leading edge stator blades on its noise reduction. The DDES method and the duct acoustic analogy theory based on the penetrable data surface were used for noise prediction. The results showed that the three kinds of wave leading edge blades were effective in reducing the rotor-stator interaction tonal noise and also have a certain inhibitory effect on broadband noise. The A10W15 stator blade can effectively reduce broadband noise in the frequency range of 2200 - 4200 Hz. When the amplitude is increased to 20, the noise reduction effect is further enhanced. However, when the amplitude is increased to 30, the broadband noise reduction effect is no longer significant. Further research shows that the wave leading edge stator blades can significantly change the pressure fluctuation distribution on the leading edge and suction surface, which control the modal energy distribution. Finally, this paper analyzed multiple factors affecting the broadband noise reduction, such as the noise source cut-off and cut-on effect and correlation. The purpose of this paper is to explore the laws of the influence of wave leading edge blades on the duct noise of real fan, and to reveal its noise control mechanism. .

Late Eocene–early Miocene provenance evolution of the Crocker Fan in the southern South China Sea

There are many large-scale Cenozoic sedimentary basins with plentiful river deltas,deep-water fans and carbonate platforms in the southern South China Sea.The Crocker Fan was deposited as a typical submarine fan during the late Eocene–early Miocene,and stretches extensively across the entire Sarawak–Sabah of the northern Borneo area.However,systematic analyses are still lacking regarding its sediment composition and potential source suppliers.No consensus has been reached yet on the provenance evolution and sedimentary infilling processes,which seriously impeded the oil-and-gas exploration undertakings.By combining with sedimentaryfacies identification,heavy mineral assemblages,elemental geochemistry and detrital zircon U-Pb dating,this paper aims to generalize an integrated analysis on the potential provenance terranes and restore source-to-sink pathways of the Crocker Fan.In general,the Crocker Fan was initially formed over the Cretaceous–lower/middle Eocene Rajang Group by an angular Rajang unconformity.The continual southward subduction of the protoSouth China Sea resulted in magmatic activities and subsequent regional deformation and thrusting along the Lupar Line in the northern Borneo.The lowermost Crocker sequence is featured by a thick conglomerate layer sourced from in-situ or adjacent paleo-uplifts.From the late Eocene to the early Miocene,the Crocker Fan was constantly delivered with voluminous detritus from the Malay Peninsula of the western Sundaland.The Zengmu Basin was widely deposited with delta plain and neritic facies sediments,while the Brunei-Sabah Basin,to the farther east,was ubiquitously characterized by turbiditic sequences.The Crocker Fan successions are overall thick layers of modest-grained sandstones,which formed high-quality reservoirs in the southern South China Sea region.

Effect of Pre-Swirling Flow on Performance and Flow Fields in Semi-Opened Axial Fan

In this study, we tried to improve the performance by giving a pre-swirling flow to the radial inflow that occurred in the semi-opened axial fan. In addition, the flow fields of rotor outlet were clarified experimentally, and the effect of pre-swirling flow was considered. The experiment was carried out using a performance test wind tunnel with a square cross section of 880 mm. Three types of casings were prepared, in which the blade tip protruded 0%, 20%, and 40% of the meridional chord length. They were called R25, R15, and R05, respectively, in the casing bellmouth model code. Guide blades for generating a pre-swirling flow were installed on the vertical wall surface of the casing. In addition, a vertical wall was installed 60% upstream of the meridional chord length as an obstacle to prevent axial inflow. The velocity fields of the rotor outlet were measured using a hot-wire anemometer. From the results, the pre-swirling flow did not significantly affect the fan performance. When there was no obstacles wall upstream, there was a partial increase in efficiency, but the difference was not so large. When there was an obstacle wall upstream, the efficiency increased overall in the case of R15, but in the case of R05, the efficiency increased only in the low flow rate region, and conversely decreased in the high flow rate region. By observing the blade outlet flow fields when the performance was improved, it was confirmed that the influence of the tip leakage vortex was weakened.

Flood risk on arid alluvial fans:a case study in the Joghatay Mountains,Northeast Iran

Among the common hazards related to alluvial fans,flooding is one of the most important.Nonetheless,in populated alluvial fans,not only the natural processes are effective in floods,but the artificial structures and modifications can change the behavior of flooding and its potential risks.This study aims to indicate the flood-prone landforms in a set of populated alluvial fans in an arid region and investigate the role of anthropogenic activities in controlling/exacerbating flooding in alluvial fans.To achieve this goal,15 Ground Range Detected in High resolution(GRDH)SAR Sentinel-1 images,covering a total of 24 alluvial fans,were acquired.Pre-processing and post-processing steps were applied to all images to identify flood-prone sections of the studied alluvial fans.The results showed that feeder channels,spreading sites,and wide interfluves are the most flood-prone landforms of alluvial fans.In terms of anthropogenic modifications to mitigate flooding,a rampart system is distributed in the study area.Ramparts are levee like structures formed from the fan material.They aim to mitigate flood hazard on residential areas,infrastructures,and agricultural lands of the study area.Results show that the rampart system can reduce the danger of floods,but it cannot be considered a long-term solution.Therefore,a comprehensive flood protection system distributed throughout the whole alluvial fan system is needed.Results also reveal that in regions where flood monitoring is challenging,SAR images can be used as a freely available data set to monitor and identify flooding hotspots.

Sedimentary Processes and Depositional Characteristics of Coarse-grained Subaqueous Fans along Steep Slopes in a Lacustrine Rift Basin:A Case Study from the Dongying Depression,Bohai Bay Basin,China

Coarse-grained subaqueous fans are vital oil and gas exploration targets in the Bohai Bay basin,China.The insufficient understanding of their sedimentary processes,depositional patterns,and controlling factors restricts efficient exploration and development.Coarse-grained subaqueous fans in the Yong′an area,Dongying Depression,are investigated in this study.These fans include nearshore subaqueous fans,and sublacustrine fans,and their sedimentary processes,depositional patterns and distribution characteristics are mainly controlled by tectonic activity and paleogeomorphology.Nearshore subaqueous fans developed near the boundary fault during the early–middle deposition stage due to strong tectonic activity and large topographic subsidence.Early sublacustrine fans developed at the front of the nearshore subaqueous fans in the area where the topography changed from gentle to steep along the source direction.While the topography was gentle,sublacustrine fans did not develop.During the late weak tectonic activity stage,late sublacustrine fans developed with multiple stages superimposed.Frequent fault activity and related earthquakes steepened the basin margin,and the boundary fault slopes were 25.9°–34°.During the early–middle deposition stage,hyperpycnal flows triggered by outburst floods developed.During the late deposition stage,with weak tectonic activity,seasonal floods triggered hyperpycnal flows,and hybrid event beds developed distally.

A Numerical Investigation on the Influence of the Circular Ring on the Aerodynamic Noise Generated by a Cooling Fan

The influence of the width of the circular ring of a car cooling fan on the aerodynamic noise is investigated numerically through the determination of the overall sound pressure level(OASPL).The results demonstrate that when the circular rings cover near 2/3 of the width of the blade tips of the rotor in the axis direction,the rotor has the lowest OASPL and the related total pressure efficiency and flow mass rate are better than the corresponding values obtained for a reference rotor without a circular ring.With increasing the width of the circular ring in the axis direction,the tip vortex around the trailing edge of the blade tip becomes smaller and finally disappears.Meanwhile,a separated flow field arises gradually and then grows in size around the middle of the junction of the blade tips with the ring.When the circular rings cover nearly 2/3 s of the width of the blade tips of the fan in the axis direction,the extension of the separated flow around the blade’s tip attains a minimum.

Diversity of depositional architecture and sandbody distribution of sublacustrine fans during forced regression: A case study of Paleogene Middle Sha 3 Member in Dongying Sag, Bohai Bay Basin, East China

Currently, the differences in gravity flow deposits within different systems tracts in continental lacustrine basins are not clear. Taking the middle submember of the third member of Paleogene Shahejie Formation(Sha 3 Member) in the Shishen 100 area of the Dongying Sag in the Bohai Bay Basin as an example, the depositional architecture of sublacustrine fans during forced regression and the impact of the fourth-order base-level changes on their growth were investigated using cores, well logs and 3D seismic data. Sublacustrine fans were mainly caused by hyperpycnal flow during the fourth-order base-level rise, while the proportion of slump-induced sublacustrine fans gradually increased during the late fourth-order base-level fall. From rising to falling of the fourth-order base-level, the extension distance of channels inside hyperpycnal-fed sublacustrine fans reduced progressively, resulting in the transformation in their morphology from a significantly channelized fan to a skirt-like fan. Furthermore, the depositional architecture of distributary channel complexes in sublacustrine fans changed from vertical aggradation to lateral migration, and the lateral size of individual channel steadily decreased. The lobe complex's architectural patterns evolved from compensational stacking of lateral migration to aggradational stacking, and the lateral size of individual lobe steadily grew. This study deepens the understanding of depositional features of gravity flow in high-frequency sequence stratigraphy and provides a geological foundation for the fine development of sublacustrine fan reservoirs.

Hybrid URANS/LES Method of Flow Fields in Axial-flow Compressor Rotor Rotor

Accurate and efficient prediction of the aerodynamic performance and flow details of axial-flow com-pressors is of great engineering application value for the aerodynamic design and flow control of axial-flow compres-sors.In this work,a delayed detached eddy simulation method is developed and applied to numerically simulate the tur-bulent channel flow and the aerodynamic performance of NASA Rotor 35.Several acceleration techniques including parallel implementation are also used to speed up the iteration convergence.The mean velocity distribution and Reyn-olds stress distribution in the boundary layer of turbulent channel flow and the aerodynamic performance curve of NASA Rotor 35 are predicted.The good agreement between the present delayed detached eddy simulation results and the available direct numerical simulation results or experimental data confirms the effectiveness of the developed meth-od in the accurate and efficient prediction of complex flow in turbomachinery.

断陷湖盆陡坡带扇三角洲—滑塌扇复合扇体的沉积演化及油气地质意义——以中非地区Melut盆地A凹陷白垩系为例

【目的】扇三角洲—深水滑塌扇组成的复合扇体作为断陷盆地陡坡带重要的粗粒沉积体系和油气储层,其展布范围、演化期次、成藏模式等一直是湖盆沉积和成藏研究的热点。【方法】以中非地区Melut盆地A凹陷高精度三维地震和钻测井资料为基础,采用岩心观察、层序划分、地震反射特征与地震属性分析等方法,对扇三角洲—滑塌扇复合扇体的沉积特征与演化规律进行了研究。【结果与结论】发现研究区复合扇体的沉积相类型包括扇三角洲和重力流成因的滑塌扇,滑塌扇具有两类形貌特征,第一类为受坡折控制的线状供源滑塌扇,第二类为受较陡地形坡度控制的单点供源多级滑塌扇。白垩系研究层段刻画出五期扇体,单期复合扇体内部具有退积特征,多期复合扇体具有“先进积、后退积”的垂向演化特征,其中下白垩统Renk组沉积末期复合扇体规模最大,达到148 km^(2)。复合扇体演化主要受幕式构造活动、古地貌和物源供给,以及相对湖平面变化的影响,构造活动强烈、物源供给充足、短轴构造隆升幅度大的时期,复合扇体规模更大,相对湖平面下降初期和上升初期滑塌扇最为发育。提出A凹陷早白垩世和晚白垩世发生沉积格局转换的新认识,明确了断陷期陡坡带扇三角洲-滑塌扇复合扇体的勘探潜力,指导了勘探部署。