检索结果-南通市图书馆

The Influence of Wedge Diffuser Blade Number and Divergence Angle on the Performance of a High Pressure Ratio Centrifugal Compressor

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2018年第1期27卷 17-24页

作者： WANG Yi han ge LU Xingen ZHU Junqiang School of Aeronautics and Astronautics Central South UniversityChangsha 410083China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China

Wedge diffuser is widely used in centrifugal compressors due to its high performance and compact size. This paper is aimed to research the influence of wedge diffuser blade number and divergence angle on centrifugal compressor performance. The impact of wedge diffuser blade number on compressor stage performance is investigated, and then the wedge diffusers with different divergence angle are studied by varying diffuser wedge angle and blade number simultaneously. It is found that wedge diffuser with 27 blades could have about 0.8% higher adiabatic efficiency and 0.14 higher total pressure ratio than the wedge diffuser with 19 blades and the best compressor performance is achieved when diffuser divergence angle is 8.3°.These results could give some advices on centrifugal compressor design.

关键词： Wedge diffuser Blade number Diffuser angle High pressure ratio Centrifugal compressor

Numerical simulation of underwater explosion bubble with a refined interface treatment

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2015年第4期58卷 91-100页

作者： JIANG Liang ge han FENG ChengLiang CHEN DaRong State Key Laboratory of Tribology Tsinghua University Ocean College Zhejiang University School of Mathematics and Systems Science Beijing University of Aeronautics and Astronautics

With the intermediate flow states predicted by local two phase Riemann problem,the modified ghost fluid method(MGFM)and its variant(r GFM)have been widely employed to resolve the interface condition in the simulation of compressible multi-medium *** this work,the drawback of the construction procedure of local two phase Riemann problem in r GFM was investigated in detail,and a refined version of the construction procedure was specially developed to make the simulation of underwater explosion bubbles more accurate and *** the refined r GFM,the fast and accurate particle level set method was also adopted to achieve a more effective and computationally efficient capture of the evolving multi-medium interfaces during the *** demonstrate the improvement brought by current refinement,several typical numerical examples of underwater explosion bubbles were performed with original r GFM and refined r GFM,*** results indicate that,when compared with original r GFM,numerical oscillations were effectively removed with the proposed ***,with present refined treatment of interface condition,a more accurate and robust simulation of underwater explosion bubbles was accomplished in this work.

关键词： underwater explosion MGFM rGFM multi-medium flow particle level set method

Investigation on Multiple Cylindrical Holes Casing Treatment for Transonic Axial Compressor Stability Enhancement

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2014年第4期23卷 346-353页

作者： YANG Chengwu ZHAO Shengfeng LU Xingen han ge ZHU Junqiang Key Laboratory of Light-duty Gas-turbine/Institute of Engineering Thermophysics Chinese Academy of Sciences University of Chinese Academy of Sciences

Casing treatment is one possible way of regaining axial compressor operating range. However, most of casing treatments extend the operating range with the cost of efficiency penalty. A new form of multiple cylindrical holes casing treatment(MHCT) with pre-swirl blowing for the NASA Rotor-37 has been designed based on profound understanding of the stall inception. Unsteady numerical simulations have been performed for Rotor-37 with and without MHCT. Parametric studies of the total extraction holes area and their axial locations show that the compressor performance deteriorates as the area ratio increases but the stall margin is extended and there is an optimum extraction holes axial location for stall margin extending. The better configuration of MHCT could extend the stall margin by 6.2% with only 0.23% peak efficiency reduction. Detailed analysis of the physical mechanism behind the stall margin improvement shows that the casing treatment could eliminate the passage blockage by suppressing breakup of tip leakage vortex and decrease the blade load in tip region, which both contribute to improve stall margin of transonic axial compressors.

关键词： Casing treatment Transonic axial compressor Stall margin extending Numerical simulation

Mass Spectrometric Fragmentation of 1,8-Bis[4-substituted- (oxazolin-2-yl)] anthracenes: Ring-contraction Rearrangement of Oxazoline Ring under Electron-Impact Ionization Conditions

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2006年第6期22卷 753-755页

作者： JIAO Peng MA Lin-ge ZhanG Qi-han XU Jia-xi Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education College of Chemistry and Molecular Engineering Peking University Bering 100871 P. R. China

The mass spectrometric fragmentation of 1,8-bis [ 4-substituted （oxazolin-2-yl） ] anthracenes （AnBOXes） was investigated by using mass-analyzed ion kinetic energy spectrometry under electron-impact ionization conditions. All the compounds could undergo a ring contraction by the loss of an RCH = CH2 molecule to form 1-oxazirinyl-8-（oxazolin- 2-yl） anthracene ions, which could further lose an R radical, followed by the loss of oxazoline. These ions could also eliminate an R radical and subsequently undergo ring-contraction rearrangements to lose a CHCH2O fragraent and an epoxide molecule, respectively. The ions that are formed could further lose CHCH2O and CH2 = CH fragments. Several ring-contraction rearrangements of the oxazoline ring were observed under electron-impact ionization conditions.

关键词： Bis-oxazoline EI-MS Fragmentation Ring contraction

Effect of Non-Axisymmetric End Wall on a Highly Loaded Compressor Cascade in Multi-Conditions

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2021年第4期30卷 1363-1375页

作者： HUANG Song YANG Chengwu LI Ziliang han ge ZHAO Shengfeng LU Xin’gen Key Laboratory of Light-duty Gas-turbine Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

As an effective method to influence end wall flow field,non-axisymmetric profiled end wall can improve the aerodynamic performance of compressor *** a highly loaded low pressure compressor cascade,called V103,the study found the optimal non-axisymmetric profiled end wall decreases total pressure loss coefficient by 4.57%,5.48%and 3.04%under incidences of–3°,0°,and 3°,respectively,compared with those of the planar end *** optimal non-axisymmetric profiled end wall changes the structure of secondary flow in hub region,generating a corner vortex near suction surface,inhibiting the development of the passage vortex towards suction surface and reducing flow *** the inlet Mach numbers are 0.62 and 0.72,the total pressure loss coefficient decreases by 3.19%and 4.58%for optimal non-axisymmetric profiled end wall compared with those of the planar end *** optimal non-axisymmetric profiled end wall increases total pressure loss near hub region in blade passage under different inlet Mach numbers,the peak value and region of high loss coefficient above 10%span in blade passage significantly *** addition,different incidences affect the secondary flow streamlines and vortex structure near the cascade hub region,however,different inlet Mach numbers hardly change the secondary flow streamlines and vortex *** short,the optimal non-axisymmetric profiled end wall shows better aerodynamic performance than the planar end wall for the highly loaded compressor cascade in multi-conditions.

关键词： non-axisymmetric profiled end wall total pressure loss highly loaded compressor cascade passage vortex

Inducer/Exducer Matching Characteristics inside Tandem Impellers of a Highly Loaded Centrifugal Compressor

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2020年第4期29卷 928-944页

作者： LI Ziliang ZHAO Shengfeng LU Xin’gen han ge YANG Chengwu ZHU Junqiang Key Laboratory of Light-Duty Gas-Turbine Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

A centrifugal compressor usually operates with low isentropic efficiency and a terrible stable operating range, resulting from the complex impeller flow structure companied with the intense interaction among the impeller and the diffuser downstream. In many studies, the potential of centrifugal compressor tandem-impeller configurations for improving the compressor has been demonstrated. Whereas, compared with the convincing results on the tandem-designed axial compressors, the results on tandem impellers are limited and contradictory. Very little insight has been provided into the flow mechanisms inside tandem impellers, which is considered to be the primary reason for the confusion in tandem impeller design and application. Tandem impellers are expected to exhibit a totally different behavior due to the intense aerodynamic interaction between the inducer and the exducer, which substantially contributes to the flow structure and the compressor performance change. In the present study, a numerical study of a highly-loaded centrifugal compressor with various tandem designs was conducted to explore the inducer/exducer matching characteristics and the underlying flow mechanism inside tandem impellers. Two tandem impeller design parameters, namely, the inducer/exducer clocking fraction and the axial gap(overlap), were considered in the tandem impeller design process. The tandem impeller was also compared to the existing conventional impeller which the tandem impeller was redesigned for. The results demonstrated that the tandem-designed impeller can improve the centrifugal compressor stage performance and intense inducer/exducer interaction can be observed with changes in the clocking fraction and the axial gap(overlap). The tandem impeller performance is sensitive to changes in axial gap(overlap) when the suction side of the exducer blade is circumferentially close to the inducer blade. The fundamental reason for the performance variation in the inducer and the exducer l

关键词： highly loaded centrifugal compressor tandem impeller inducer/exducer matching flow mechanism Kutta condition

Numerical investigation of flow mechanisms of tandem impeller inside a centrifugal compressor

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2019年第12期32卷 2627-2640页

作者： Ziliang LI Xin’gen LU Shengfeng ZHAO ge han Chengwu YANG Yanfeng ZhanG Key Laboratory of Light-Duty Gas-Turbine Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

This study numerically investigated a single stage centrifugal compressor "Radiver" with a wedge diffuser and several tandem-designed impellers to explore the flow phenomena within the tandem impeller and the potential to enhance compressor *** results demonstrate that tandem design and clocking fraction(ks)significantly affects the compressor *** compressor stage with tandem impellers of Series A of boundary layer growth interruption alone are observed to have a widely operating range but efficiency and total pressure ratio penalty compared with that of conventional *** tandem impeller with at least the same impeller efficiency as the conventional design is considered as a critical design criteria so that further modification process based on the flow characteristic of tandem impeller is *** order to restrain the inducer wake and exducer shock losses,parameters modification of blade angle and thickness distributions are necessary and the modified tandem impeller of Series B is *** modified tandem impeller with 25%clocking arrangement shows an 8.45%stall margin increase and maintains the total pressure ratio and efficiency as the conventional design,which proves the potential of tandem impeller to improve compressor stage *** is noteworthy that the tandem impellers of Radiver have not shown obviously balanced exit flow field and the fundamental mechanism of stall margin extending of tandem impeller lies on the improved impeller/diffuser matching performance resulting from the incidence angle variation at diffuser inlet.

关键词： Centrifugal compressor stage Flow mechanism Impeller/diffuser matching Stall margin Tandem impeller

Vortex dynamics and entropy generation in separated transitional flow over a compressor blade at various incidence angles

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2022年第3期35卷 42-52页

作者： Mingyang WANG Ziliang LI ge han Chengwu YANG Shengfeng ZHAO Yanfeng ZhanG Xin’gen LU Key Laboratory of Light-Duty Gas-Turbine Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

The transition process within a Laminar Separation Bubble(LSB)that formed on a compressor blade surface was investigated using Large Eddy Simulations(LESs)at a Reynolds number of 1.5×10;and incidence angles of 0°,+3°,and+5°.The vortex dynamics in the separated shear layers were compared at various incidence angles and its effects on the loss generation were clarified through entropy *** showed that transition onset,which was accurately identified by the Linear Stability Theory(LST),was significantly promoted at the increased incidence *** such,the development of LSB was suppressed and the relative role of viscous instability played in the transition process was *** the incidence angle of 0°,two-dimensional spanwise vortices detached from the blade surface and roiled up periodically,which were further stretched and eventually evolved into large-scale hairpin *** time passed,the fully developed hairpin vortices broke down into small-scale ***,the flow near the wall reversely ejected into the outer separated shear layers and a sweeping process happened subsequently,forcing the separated shear layers to reattach and accelerating the generation of turbulent *** comparison,the strength of vortex rolling-up was weakened at higher incidence angles,and the vortex pairing and breakdown of large-scale vortices were less ***,the level of turbulent fluctuations that generated in the separated shear layers was *** entropy analysis showed that the turbulent dissipation effect related to the Reynolds shear stresses determined the largest amount of positive entropy generation,which declined to a lower level as the incidence angle increased from 0°to+5°.Correspondingly,the profile loss was reduced by 50.4%.

关键词： Aerodynamic performance Compressor airfoil Entropy Incidence angle Separation bubble Vortex dynamics

Microstructure,Properties and Heat Treatment Process of Powder Metallurgy Superalloy FGH95

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2006年第5期13卷 65-68页

作者： GUO Wei-min WU Jian-tao ZhanG Feng-ge ZHAO Ming-han High Temperature Materials Research Institute Central Iron and Steel Research Institute Beijing 100081 China

Microstructure and properties of nickel based powder metallurgy （PM） superalloy were presented. Effects of nonmetallic inclusions and heat treatment on microstructure and properties were. discussed. Development tend... 详细信息

关键词： microstructure property PM superalloy heat treatment