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Journal of Thermal Science 2018年第6期27卷 505-515页

作者： LIU Hanru YUE Shaoyuan WANG Yangang ZHANG Jun School of Power & Energy Northwestern Polyteclmical University Xi'an 710129 China Shaanxi Key Laboratory of Internal Aerodynamics in Acro-Engine Xi'an 710129 China

To investigate the effects of matching characteristics of tandem cascade on the performance and flow at large angle of attack, the unsteady numerical simulation has been implemented. The influences of different turning angle ratio(TR) and chord length ratio(CR) of two blades and the relative angle of attack of rear blade(Delta) are analyzed. The numerical results indicated that the tandem cascade can obtain overall performance improvement including higher static pressure ratio and lower total pressure loss with the matching parameters in the range of TR=3～5, CR=0.5～1.2, and Delta=-15°～-5°. The separation on the front blade has more prominent impact than that on the rear blade, so the performance improvement of tandem cascade is significantly dependent on the reduction of front-blade separation and loss. Regarding the rear blade, the gap injection effect can periodically control the separation. Temporal and spatial analysis of the flow field shows that the optimal-performance cases generally have much smaller wake loss for both two blades, but the unsteady characteristics of the wake loss is more apparent than that of the poor performance cases.

关键词： tandem cascade unsteady simulation matching parameters aerodynamics performance flow loss

Application of tandem cascade to Design of Fan Stator with Supersonic Inflow

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Chinese Journal of Aeronautics 2010年第1期23卷 9-14页

作者： Li Qiushi,Wu Hong,Zhou Sheng School of Jet Propulsion,Beijing University of Aeronautics and Astronautics,Beijing 100191,China School of Jet Propulsion Beijing University of Aeronautics and Astronautics Beijing 100191 China

This article proposes a tandem cascade constructed to tackle the thorny problem of designing the high-loaded stator with a supersonic inflow and a large turning angle. The front cascade adopts a supersonic profile to reduce the shock wave intensity turning the flow into subsonic,while the rear cascade adopts a subsonic profile with a large camber offering the flow a large turning angle. It is disclosed that the losses would be minimized if the leading edge of the rear cas- cade lies close to the pressure side of the front cascade at a distance of 20% pitch in pitch-wise direction without either axial spacing or overlapping in axial direction. The 2D numerical test results show that,with the inflow Mach number of 1.25 and the turning angle of 52° ,the total pressure loss coefficient of the tandem cascade reaches 0. 106 ,and the diffusion factor 0. 745. Finally,this article has designed and simulated a high-loaded fan stage with the proposed tandem stator,which has the pressure ratio of 3.15 and the efficiency of 86.32% at the rotor tip speed of 495.32 m/s.

关键词： fan/compressor tandem cascade stator supersonic inflow

Complicated flow in tip flow field of a compressor tandem cascade using delayed detached eddy simulation

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Chinese Journal of Aeronautics 2024年第8期37卷 63-78页

作者： Botao ZHANG Xiaochen MAO Bo LIU Hejian WANG Zonghao YANG School of Power and Energy Northwestern Polytechnical UniversityXi’an 710129China Taihang Laboratory Chengdu 610000China

The complex flow characteristics in the tip region of a tandem cascade with tip clearance have been calculated and analyzed using Delayed Detached Eddy Simulation(DDES).The coherent mechanism of the vortex structures near the blade tip was discussed,and the unsteady behaviors and features in the tip flow field were ***,the interaction between the tip leakage flow and the gap jet was *** results show that,compared to the datum cascade,the blade tip load of the rear blade increases while that of the front blade *** fluctuations of the tandem cascade are mainly caused by the interaction between the tip leakage flow and gap jet,and by the mixing of the vortex structures,but there is no essential change in the spectrum feature of the tip leakage ***,a detailed analysis of the development of vortices in the tip region is conducted by the topological structures of the flow *** with the three-dimensional vortex structures,the schematic diagram of the vortex system of the datum single-row cascade and tandem cascade is summarized.

关键词： tandem cascade Tip leakage flow Delayed Detached Eddy Simulation(DDES) Unsteady flow Gap jet Topological structure

Design strategy and relevant flow mechanisms of highly loaded 3D compressor tandem cascades

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Chinese Journal of Aeronautics 2024年第7期37卷 220-235页

作者： Xiaochen MAO Yunyu WANG Zhihua DING Hao CHENG Bo LIU School of Power and Energy Northwestern Polytechnical UniversityXi’an 710129China The National Key Laboratory of Science and Technology on Aerodynamic Design and Research Xi’an 710129China Xi’an Thermal Power Research Institute Co.Ltd Xi’an 710072China

To investigate the design strategy of highly loaded tandem cascades at both the midspan and endwall,the overall performance and flow mechanisms of four typical tandem cascades based on the optimization were analyzed from multiple perspectives *** results show that the interference effects on the Front Blade(FB)and Rear Blade(RB)should not be overlooked during the design phase,and the design strategies at the midspan and endwall are completely *** the midspan,the optimization aims to increase the interference effects and the strength of the gap jet while maintaining the same load on the FB and ***,the endwall optimal airfoil exhibits weakening interference effects,advancement of the gap jet location,and load transfer from the FB to *** further analysis of flow characteristics,the midspan optimal airfoil is beneficial for inhibiting the low-energy fluid from interacting with the suction surface of RB under the design condition,but results in earlier occurrence of corner *** endwall optimal airfoil helps suppress the development of the secondary flow and delay the onset of corner ***,by combining the benefits of these two design approaches,additional forward sweep effects are achieved,further enhancing the performance of the tandem cascade.

关键词： tandem cascade Interference effect Vortex structure Load split Compressor

Control of Secondary Flow in a Low Solidity Circular cascade Diffuser

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Journal of Thermal Science 2012年第4期21卷 384-390页

作者： Daisaku Sakaguchi Takuji Fujii Hironobu Ueki Masahiro Ishida Hiroshi Hayami Nagasaki University 1-14 Bunkyo-machi Kyushu University (retired)

According to the previous experimental works on the low solidity circular cascade diffuser (LSD), a pressure recovery of a centrifugal blower was improved by the LSD significantly in a wide range of flow rate, and the pres-sure recovery was improved further by the LSD with a tandem cascade in comparison with the LSD with a sin-gle-row cascade. In the present study, the flow behavior in the LSD with the tandem cascade has been analyzed numerically by using the commercial CFD code of ANSYS-CFX12. It was shown clearly that the higher pressure recovery was achieved by applying the LSD with the tandem cascade, and the high pressure recovery is based on the high pressure rise in the vaneless space upstream of the LSD and the high blade loading of the front blade of the LSD. The high pressure recovery in the LSD could be achieved by controlling the flow separation on the suc-tion surface of the front blade and also on that of the rear blade due to formation of the favorable secondary flow and due to increase in mass flow passing through the slit section between the front and rear blades.

关键词： LSD (Low solidity circular cascade diffuser) Centrifugal blower Range enhancement tandem cascade

Optimal Design Criteria of tandem Configuration for High-Load Compressor cascades

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Journal of Thermal Science 2024年第6期33卷 2047-2058页

作者： MAO Xiaochen JIAO Yingchen CHENG Hao ZHANG Botao LIU Bo School of Power and Energy Northwestern Polytechnical UniversityXi'an 710129China The National Key Laboratory of Science and Technology on Aerodynamic Design and Research Xi'an 710129China Xi'an Thermal Power Research Institute Co. Ltd.Xi'an 710072China

Axial overlap(AO)and percent pitch(PP)are considered as key position configuration parameters that affect the tandem cascade *** objective of the current study is to investigate the optimal design criteria for these two parameters in tandem cascades of subsonic highly-loaded two-dimensional *** that,the influence mechanisms of AO and PP are explored *** results show that higher PP is beneficial for decreasing rear blade(RB)load,but an invalidity of gap flow occurs when it approaches *** change in AO has an influence on the adverse pressure gradient of the front blade(FB),and it also affects the gap flow strength and FB wake ***,the optimal design criteria for AO and PP are obtained in a large design space,which clarifies the matching relationship of the two parameters at different operating *** best global range of AO is about-0.05 to 0.05 while PP is between 0.85 to 0.92,and PP should be smaller to avoid performance degradation as AO *** to the fault tolerance in practical applications,PP should be closer to the lower bound to ensure that the deterioration boundary is wide enough.

关键词： axial compressor tandem cascade axial overlap percent pitch optimal design criteria