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Quantitative temperature imaging at elevated pressures and in a confined space with CH4/air laminar flames by filtered Rayleigh scattering 被引量:2
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作者 Bo Yan Li Chen +6 位作者 Meng Li Shuang Chen Cheng Gong Fu-Rong Yang Yun-Gang Wu Jiang-Ning Zhou Jin-He Mu 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第2期315-320,共6页
Laminar methane/air premixed flames at different pressures in a newly developed high-pressure laminar burner are studied through Cantera simulation and filtered Rayleigh scattering(FRS).Different gas component fractio... Laminar methane/air premixed flames at different pressures in a newly developed high-pressure laminar burner are studied through Cantera simulation and filtered Rayleigh scattering(FRS).Different gas component fractions are obtained through the detailed numerical simulations.And this approach can be used to correct the FRS images of large variations in a Rayleigh cross section in different flame regimes.The temperature distribution above the flat burner is then presented without stray light interference from soot and wall reflection.Results also show that the extent of agreement with the single point measurement by the thermocouple is<6%.Finally,this study concludes that the relative uncertainty of the presented filtered Rayleigh scattering diagnostics is estimated to be below 10%in single-shot imaging. 展开更多
关键词 filtered RAYLEIGH SCATTERING high-pressure COMBUSTION SIMULATOR TEMPERATURE measurement
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A novel approach of jet polishing for interior surface of small-grooved components using three developed setups
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作者 Qinming Gu Zhenyu Zhang +6 位作者 Hongxiu Zhou Jiaxin Yu Dong Wang Junyuan Feng Chunjing Shi Jianjun Yang Junfeng Qi 《International Journal of Extreme Manufacturing》 SCIE EI CAS CSCD 2024年第2期428-447,共20页
It is a challenge to polish the interior surface of an additively manufactured component with complex structures and groove sizes less than 1 mm.Traditional polishing methods are disabled to polish the component,meanw... It is a challenge to polish the interior surface of an additively manufactured component with complex structures and groove sizes less than 1 mm.Traditional polishing methods are disabled to polish the component,meanwhile keeping the structure intact.To overcome this challenge,small-grooved components made of aluminum alloy with sizes less than 1 mm were fabricated by a custom-made printer.A novel approach to multi-phase jet(MPJ)polishing is proposed,utilizing a self-developed polisher that incorporates solid,liquid,and gas phases.In contrast,abrasive air jet(AAJ)polishing is recommended,employing a customized polisher that combines solid and gas phases.After jet polishing,surface roughness(Sa)on the interior surface of grooves decreases from pristine 8.596μm to 0.701μm and 0.336μm via AAJ polishing and MPJ polishing,respectively,and Sa reduces 92%and 96%,correspondingly.Furthermore,a formula defining the relationship between linear energy density and unit defect volume has been developed.The optimized parameters in additive manufacturing are that linear energy density varies from 0.135 J mm^(-1)to 0.22 J mm^(-1).The unit area defect volume achieved via the optimized parameters decreases to 1/12 of that achieved via non-optimized ones.Computational fluid dynamics simulation results reveal that material is removed by shear stress,and the alumina abrasives experience multiple collisions with the defects on the heat pipe groove,resulting in uniform material removal.This is in good agreement with the experimental results.The novel proposed setups,approach,and findings provide new insights into manufacturing complex-structured components,polishing the small-grooved structure,and keeping it unbroken. 展开更多
关键词 abrasive air jet polishing multi-phase jet polishing interior curved surface small-grooved component aluminum alloy
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Semi-analytic solution of Eringen's two-phase local/nonlocal model for Euler-Bernoulli beam with axial force 被引量:1
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作者 Licheng MENG Dajun ZOU +4 位作者 Huan LAI Zili GUO Xianzhong HE Zhijun XIE Cunfa GAO 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2018年第12期1805-1824,共20页
Eringen’s two-phase local/nonlocal model is applied to an Euler-Bernoulli nanobeam considering the bending-induced axial force, where the contribution of the axial force to bending moment is calculated on the deforme... Eringen’s two-phase local/nonlocal model is applied to an Euler-Bernoulli nanobeam considering the bending-induced axial force, where the contribution of the axial force to bending moment is calculated on the deformed state. Basic equations for the corresponding one-dimensional beam problem are obtained by degenerating from the three-dimensional nonlocal elastic equations. Semi-analytic solutions are then presented for a clamped-clamped beam subject to a concentrated force and a uniformly distributed load, respectively. Except for the traditional essential boundary conditions and those required to be satisfied by transferring an integral equation to its equivalent differential form, additional boundary conditions are needed and should be chosen with great caution, since numerical results reveal that non-unique solutions might exist for a nonlinear problem if inappropriate boundary conditions are used. The validity of the solutions is examined by plotting both sides of the original integro-differential governing equation of deflection and studying the error between both sides. Besides, an increase in the internal characteristic length would cause an increase in the deflection and axial force of the beam. 展开更多
关键词 nonlocal elasticity internal characteristic length size effect nanobeam axial force unique solution
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Super-resolution DOA estimation for correlated off-grid signals via deep estimator 被引量:1
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作者 WU Shuang YUAN Ye +1 位作者 ZHANG Weike YUAN Naichang 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2022年第6期1096-1107,共12页
This paper develops a deep estimator framework of deep convolution networks(DCNs)for super-resolution direction of arrival(DOA)estimation.In addition to the scenario of correlated signals,the quantization errors of th... This paper develops a deep estimator framework of deep convolution networks(DCNs)for super-resolution direction of arrival(DOA)estimation.In addition to the scenario of correlated signals,the quantization errors of the DCN are the major challenge.In our deep estimator framework,one DCN is used for spectrum estimation with quantization errors,and the remaining two DCNs are used to estimate quantization errors.We propose training our estimator using the spatial sampled covariance matrix directly as our deep estimator’s input without any feature extraction operation.Then,we reconstruct the original spatial spectrum from the spectrum estimate and quantization errors estimate.Also,the feasibility of the proposed deep estimator is analyzed in detail in this paper.Once the deep estimator is appropriately trained,it can recover the correlated signals’spatial spectrum fast and accurately.Simulation results show that our estimator performs well in both resolution and estimation error compared with the state-of-the-art algorithms. 展开更多
关键词 off-grid direction of arrival(DOA)estimation deep convolution network(DCN) correlated signal quantization error SUPER-RESOLUTION
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某声学风洞轴流风扇设计(英文) 被引量:1
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作者 屈晓力 余永生 +1 位作者 吕金磊 张文清 《风机技术》 2019年第6期56-60,I0007,共6页
采用试验研究的方式,对某声学风洞的轴流风扇性能进行验证。该风扇采用了任意涡设计方法以达到所要求的气动指标要求;通过降低风扇转速、合理匹配桨叶-止旋片数目、调整桨叶-止旋片间距及止旋片后掠等方式,降低风扇噪声。风扇的性能测... 采用试验研究的方式,对某声学风洞的轴流风扇性能进行验证。该风扇采用了任意涡设计方法以达到所要求的气动指标要求;通过降低风扇转速、合理匹配桨叶-止旋片数目、调整桨叶-止旋片间距及止旋片后掠等方式,降低风扇噪声。风扇的性能测试结果表明,风扇满足了风洞试验段的最高风速要求,当风扇转速为650r/min时,风扇的级间效率达到90%、风扇段气动效率达到84%;当试验段风速达到70m/s时,风扇出口的声压级为114d B。该风扇的研制,表明采用任意涡风扇设计方法结合上述提到的降噪措施,能够设计出气动效率高、风扇噪声低的风扇系统,可很好的运用于其他的声学风洞设计中。 展开更多
关键词 风扇噪声 风扇转速 风扇系统 轴流风扇 声学风洞 气动效率 降噪措施 声压级
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Numerical solutions of 2-D steady compressible natural convection using high-order flux reconstruction
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作者 Yaojie Yu Feng Liu +2 位作者 Tingbo Zhou Chao Gao Ya Liu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2019年第2期401-410,共10页
Low Mach number flows are common and typical in industrial applications. When simulating these flows, performance of traditional compressible flow solvers can deteriorate in terms of both efficiency and accuracy. In t... Low Mach number flows are common and typical in industrial applications. When simulating these flows, performance of traditional compressible flow solvers can deteriorate in terms of both efficiency and accuracy. In this paper, a new high-order numerical method for two-dimensional(2-D)state low Mach number flows is proposed by combining flux reconstruction(FR)and preconditioning. Firstly, a Couette flow problem is used to assess the efficiency and accuracy of preconditioned FR. It is found that the FR scheme with preconditioning is much more efficient than the original FR scheme. Meanwhile,this improvement still preserves the numerical accuracy. Using this new method and without the Boussinesq assumption,classic natural convection is directly simulated for cases of small and large temperature differences. For the small temperature difference, a p and h refinement study is conducted to verify the grid convergence and accuracy. Then, the influence of the Rayleigh number (Ra) is analyzed. By comparing with the reference results, the numerical results of preconditioned FR is very close to that calculated by incompressible solvers. Furthermore, a large temperature difference test case is calculated and analyzed, indicating this method is not limited by the Boussinesq assumption and is also applicable to heat convection with large temperature differences. 展开更多
关键词 FLUX RECONSTRUCTION PRECONDITIONING method Low MACH flows Natural convection
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Study on Acoustically Transparent Test Section of Aeroacoustic Wind Tunnel
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作者 Jinlei Lv Ning Wang +2 位作者 Daxiong Liao Yongsheng Yu Xinglong Gao 《Journal of Applied Mathematics and Physics》 2018年第1期1-10,共10页
On the purpose of accurate data acquisition for the aeroacoustic testing mostly in open jet test section of aeroacoustic wind tunnel, the large scale anechoic chamber is specifically designed to build the low backgrou... On the purpose of accurate data acquisition for the aeroacoustic testing mostly in open jet test section of aeroacoustic wind tunnel, the large scale anechoic chamber is specifically designed to build the low background noise environment. A newly acoustic test section is presented in this paper, of which the contour is similar as the closed test section, and the wall is fabricated by the fiber fabric, both the characteristics of closed and open jet test section of conventional wind tunnel are combined in it. By thoroughly researching on the acoustics and aerodynamics of this acoustically transparent test section, significant progress in reducing the background noises in test section and improving the ratio of energy of the wind tunnel and some other aspects have been achieved. Acoustically transparent test section behaves better in acoustics and aerodynamics than conventional acoustic test section because of their high definition in detecting the sound sources and great performance in transmitting sounds. 展开更多
关键词 AEROACOUSTIC Experiment SOUND TRANSPARENT PROPERTY Acoustic Test SECTION Low BACKGROUND Noise SOUND Identification
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Advanced nonlinear rheology magnetorheological finishing: A review
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作者 Feng ZHAO Zhenyu ZHANG +5 位作者 Jianjun YANG Jiaxin YU Junyuan FENG Hongxiu ZHOU Chunjing SHI Fanning MENG 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2024年第4期54-92,共39页
High-performance devices usually have curved surfaces, requiring high accuracy of shape and low surface roughness. It is a challenge to achieve high accuracies for form and position on a device with low surface roughn... High-performance devices usually have curved surfaces, requiring high accuracy of shape and low surface roughness. It is a challenge to achieve high accuracies for form and position on a device with low surface roughness. However, due to the unique nonlinear rheology, magnetorheological fluids with hard abrasives are widely applied in ultra-precision surface finishing. Compared with conventional mechanical finishing, magnetorheological finishing displays obviously advantages, such as high precision shape of machined surface, low surface roughness and subsurface damage, and easy control for finishing processes. However, finishing performance depends on various factors, e.g. volume fraction and distribution of magnetic particles, types of hard abrasives and additives, strength of magnetic field, finishing forms. Therefore, a comprehensive review on related works is essential to understand the state-of-the-art of magnetorheological finishing and beneficial to inspire researchers to develop lower cost, higher machining accuracy and efficient approaches and setups, which demonstrates a significant guidance for development of high-performance parts in fields of aerospace, navigation and clinical medicine etc. This review starts from the rheological property of magnetorheological fluids, summarizing dynamically nonlinear rheological properties and stable finishing approaches. Then, the effect of components in magnetorheological fluids is discussed on finishing performance, consisting of magnetic particles, carrier fluid, additives and abrasives. Reasonable configuration of magnetorheological fluids, and different magnetorheological finishing methods are presented for variously curved surfaces. In addition, the current finishing forms and future directions are also addressed in this review. 展开更多
关键词 Finishing approaches Finishing performance Magnetorheological finishing Magnetorheological fluids Rheological property
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