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Science china(Technological Sciences) 2010年第7期53卷 1817-1823页

作者： zheng xinqian, zhang yangjun & yang mingyang state key laboratory of automotive safety and energy, tsinghua university, beijing 100084, china state key laboratory of automotive safety and energy Tsinghua University Beijing China

The pressure ratio required for a turbocharger centrifugal compressor increases with internal combustion engine power density. High pressure ratio causes a transonic flow field at the impeller inducer. Transonic flow narrows the stable flow range and de-teriorates stage efficiency. In this work, an advanced high pressure ratio transonic compressor was designed. The experimental results show that the maximum pressure ratio of this turbocharger is about 4.2, the maximum efficiency is above 80% and the stable flow range at the designed rotating speed is up to 34%. A turbocharger with this transonic compressor has been applied to some vehicle research actually, and improved power density by 40%.

关键词： turbocharger internal combustion (IC) engine compressor high pressure ratio transonic

Flow Loss Mechanism in a Supercritical Carbon Dioxide Centrifugal Compressor at Low Flow Rate Conditions

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Journal of Thermal Science 2024年第1期33卷 114-125页

作者： yang Zimu JIANG Hongsheng ZHUGE Weilin CAI Ruikai yang mingyang CHEN Haoxiang QIAN Yuping zhang yangjun state key laboratory of automotive safety and energy Tsinghua UniversityBeijing 100084China School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China

With the advantages of high efficiency and compact structure,supercritical carbon dioxide(sC02)Brayton cycles have bright prospects for development in energy conversion *** one of the core components of the power cycle,the centrifugal compressor tends to operate near the critical point(304.13 K,7.3773 MPa).Normally,the compressor efficiency increases as the inlet temperature *** the inlet temperature is close to the critical point,the density increases sharply as the temperature decreases,which results in quickly decreasing of volume flow rate and efficiency *** flow loss mechanism of the sCO_(2) compressor operating at low flow rate is studied in this *** fluid dynamics(CFD) simulations for sCO_(2)compressor were carried out at various inlet temperatures and various mass flow *** the sCO_(2)compressor operates at low volume flow rate,the flow loss is generated mainly on the suction side near the trailing edge of the *** flow loss is related to the counterclockwise vortexes generated on the suction side of the main *** vortexes are caused by the flow separation in the downstream region of the impeller passage,which is different from air compressors operating at low flow *** reason for this flow separation is that the effect of Coriolis force is especially severe for the sCO_(2) fluid,compared to the viscous force and inertial *** lower flow rates,with the stronger effect of Coriolis force,the direction of relative flow velocity deviates from the direction of radius,resulting in its lower radial *** lower radial relative flow velocity leads to severe flow separation on the suction side near the trailing edge of the main blade.

关键词： supercritical CO_(2) centrifugal compressor flow loss mechanism Coriolis force

An integrated turbocharger design approach to improve engine performance

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Science china(Technological Sciences) 2010年第1期53卷 69-74页

作者： zhang yangjun1,CHEN Tao1,ZHUGE WeiLin1,zhang ShuYong2 & XU JianZhong3 1 state key laboratory of automotive safety and energy,tsinghua university,beijing 100084,china 2 National key laboratory of Diesel Engine Turbocharging Technology,P.O.B.22,Datong 037036,china 3 Institute of Engineering Thermophysics,Chinese Academy of Sciences,beijing 100190,china state key laboratory of automotive safety and energy Tsinghua University Beijing China National key laboratory of Diesel Engine Turbocharging Technology Datong China Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing China

Turbocharging technology is today considered as a promising way for internal combustion engine energy saving and CO2 *** design is a major challenge for turbocharged engine performance *** turbocharger designer must draw upon the information of engine operation conditions,and an appropriate link between the engine requirements and design features must be carefully developed to generate the most suitable design *** objective of this research is to develop a turbocharger design approach for better turbocharger matching to an internal combustion *** development of the approach is based on the concept of turbocharger design and interaction links between engine cycle requirements and design parameter values.A turbocharger through flow model is then used to generate the design *** integrated method has been applied with success to a gasoline engine turbocharger assembly.

关键词： turbocharger design internal combustion engine integrated method through flow model

Effects of Reynolds number on the performance of a high pressure-ratio turbocharger compressor

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Science china(Technological Sciences) 2013年第6期56卷 1361-1369页

作者： zheng xinqian LIN Yun GAN BinLin ZHUGE WeiLin zhang yangjun state key laboratory of automotive safety and energy Tsinghua University beijing Power Machinery Research Institute

The effects of Reynolds number on the performance of a high pressure-ratio turbocharger compressor were investigated by both experiments and numerical simulation. The experimental results show that the pressure ratio and the efficiency of the compressor respectively decrease by 7.9% and 6.9% when Reynolds number drops from 9.86×10 5 to 2.96×10 5 . The numerical simulation predicts a similar trend as the experimental results although it underestimates the deterioration of the performance under low Reynolds number conditions. According to simulation results, the boundary layer thickness increases at the inducer, which decreases the throat area and leads to smaller choke mass flow rate. The increments of the boundary thickness are relatively small at the rear part of the impeller. The boundary layer separation flow is severe. The interaction between boundary layer separation flows and leakage flows causes the high loss region at the rear part of the impeller passage under low Reynolds number condition.

关键词： Reynolds number high pressure-ratio turbocharger centrifugal compressor internal combustion engine

Effects of pulse flow and leading edge sweep on mixed flow turbines for engine exhaust heat recovery

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Science china(Technological Sciences) 2011年第2期54卷 295-301页

作者： zhang yangjun CHEN Li ZHUGE WeiLin zhang ShuYong state key laboratory of automotive safety and energy Tsinghua University Beijing 100084 China National key laboratory of Diesel Engine Turbocharging Technology P.O.B. 22 Datong 037036 China

Recovery of heat energy from internal combustion engine exhaust will achieve significant road transportation CO2 reduction. Turbocharging and turbogenerating are most commonly used technologies to recover engine exhaust heat *** exhaust pulse flow can significantly affect the turbine performance of turbocharging and turbogenerating systems,and it is necessary to consider the pulse flow effects in turbine design and performance *** investigation was carried out by numerical simulation on the mixed flow turbine pulse flow performance and flow *** showed that the variations of the turbine efficiency and flowfiled under pulsating flow conditions demonstrate significant unsteady *** effect of blade leading edge sweep on turbine pulse flow performance was *** is shown that increasing of the leading edge sweep angle can improve the turbine average instantaneous efficiency by about 2 percent under pulsating flow conditions.

关键词： waste heat recovery mixed flow turbine pusle flow

Improving the performance of ducted fans for VTOL applications:A review

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Science china(Technological Sciences) 2022年第11期65卷 2521-2541页

作者： QIAN YuPing LUO YiWei HU Xuanyang ZENG ZeZhi zhang yangjun state key laboratory of automotive safety and energy School of Vehicle and MobilityTsinghua UniversityBeijing 10o084China

Ducted fans have been widely used in VTOL aircraft due to the high propulsion efficiency and *** efficiency and stability of ducted fans deteriorate in some flight conditions such as hovering in crosswinds or ground *** is necessary to optimize the ducted fan’s structures or apply flow control methods for better adaptions to the typical *** paper presents a detailed review on the ducted fan technology for VTOL applications,especially the methods for improving its efficiency and *** first simplified the classification categories based on boundary conditions instead of flight conditions,since the new classification method covers more situations and is easier to distinguish flow field *** flow characteristics,thrust properties and the optimal structures under different boundary conditions were summarized and ***,new configurations and flow control methods for increasing the efficiency and stability were *** newly proposed integration design between the ducted fan and the motor was emphasized for increasing the power density of the ducted *** review would be helpful to improve our understanding of the relationship between the structures,flow characteristics and thrust properties of ducted fans under different flight conditions,and inspires scientists to design high-efficiency and high-stability propulsion systems with ducted fans.

关键词： ducted fan VTOL figure ofmerit working stability aerodynamic stability

Performance Improvement of a Centrifugal Compressor for the Fuel Cell Vehicle by Tip Leakage Vortex Control

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Journal of Thermal Science 2021年第6期30卷 2099-2111页

作者： CHEN Haoxiang ZHUGE Weilin zhang yangjun MA Xuelong TAO Lin state key laboratory of automotive safety and energy Tsinghua UniversityBeijing 100084China Weichai Power Co. Ltd.Weifang 261061China Xecaturbo(Shanghai)Technology Co. Ltd.Shanghai 200241China

Heightened interests have been laid at the preliminary design and optimization of the centrifugal compressor for the fuel cell *** centrifugal compressor for fuel cell vehicle is driven by a high-speed motor;however,the limit of the motor speed makes the flow passage of the impeller long and narrow,which leads to a serious tip leakage *** tip leakage loss deteriorates the compressor *** this paper,3-D numerical simulations were carried out with the aim of investigating the tip leakage loss in a prototype centrifugal compressor for a 100 kW fuel cell *** results revealed that the mixing loss caused by the interaction between the tip leakage vortex and the downstream tip leakage flow contributed to the major part of the tip leakage *** path of the tip leakage vortex almost followed the streamwise direction,while the downstream tip leakage flow exhibited strong circumferential momentum,which referred to the fact that they were nearly ***,a flow control approach,which was realized by enhancing the blade loading around the leading edge of blade tips in this paper,was proposed to decrease the interaction angle between the tip leakage vortex and the downstream tip leakage flow and then mitigate mixing loss by changing the flow direction of the tip leakage *** results showed a smaller interaction angle was achieved in the optimized impeller compared with the baseline ***,the efficiency was also improved by 1.30%at design condition and the maximum efficiency improvement could be up to 10%at large mass flow condition of 92000 r/*** manufactured and tested,the optimized compressor was proved to achieve an isentropic efficiency of 75.84%at design condition.

关键词： centrifugal compressor fuel cell vehicle efficiency improvement tip leakage vortex mixing loss

Real-Time Instability Detection of Centrifugal Compressors Based on Motor Speed Measurements

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Journal of Thermal Science 2023年第1期32卷 310-329页

作者： CHEN Haoxiang ZHUGE Weilin QIAN Yuping zhang yangjun LIU Hongdan state key laboratory of automotive safety and energy Tsinghua UniversityBeijing 100084China Chongqing Jiangjin Shipbuilding Industry Corporation China Shipbuilding Industry CorporationChongqing 402263China

Flow instability in the centrifugal compressor should be detected and avoided for stable and safe *** to the popularity of electric centrifugal compressors,instability detection could be achieved by measuring motor signals instead of traditional aerodynamic *** this paper,the feasibility of instability detection by motor signals(*** speed and phase current)was studied *** physical structure and control method of the electric centrifugal compressor were discussed to reveal the potential of instability detection by motor *** pressure signals and motor signals measured during unsteady experiments were analyzed in the time domain and frequency *** of these signals were then compared under different operating conditions to indicate the feasibility of instability detection by motor ***,the ability of Short-Time Fourier Transform(STFT)of rotating speed signals in real-time instability detection was *** showed that the rotating speed signal is a good alternate for instability detection in spite of signal distortion,while the phase current signal can only detect surge due to the low resolution of the *** on the variations of the amplitude and frequency of rotating speed signals,the real-time instability can be captured accurately by STFT with a window size of 0.5 ***,the interference caused by the controller can be removed by STFT.

关键词： centrifugal compressor instability detection real-time rotating speed STFT

Characterization of Swirling Inflow Effects on Turbine Performance under Pulsating Flows

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Journal of Thermal Science 2022年第5期31卷 1734-1744页

作者： DING Zhanming WANG Cuicui zhang Junyue LIU Ying HOU Linlin ZHUGE Weilin zhang yangjun Science and Technology on Diesel Engine Turbocharging laboratory China North Engine Research InstituteTianjin300400China Kangyue Technology(Shandong)Co. LtdShouguangShandong262718China state key laboratory of automotive safety and energy Tsinghua UniversityBeijing100084China

The present study focuses on the influence of the swirling flows on flow behaviors and performance of a radial-flow turbocharger turbine under pulsating inflow *** characterize the effects of swirling flow,three sets of simulations of the turbine were carried out,which are an unsteady simulation under pulsating swirling inflow,an unsteady simulation under equivalent pulsating uniform inflow,and quasi-steady simulations under uniform *** proved that swirling flow has a considerable negative influence on turbine instantaneous performance and lead to 2.5%cycle-averaged efficiency reduction under pulsating flow *** inflow would lead to significant losses in both the volute and the rotor,while the pulsating inflow leads to higher losses in the rotor and shows little influence on the losses in the *** instantaneous efficiency reduction of the turbine could be correlated with the time-varying inlet swirl *** the influence of unsteady inlet swirls,the volute flow field is highly distorted and the free vortex relation is no longer *** swirling flow has strong interactions with the wake flow of the volute tongue,leading to additional *** flow angle at rotor inlet is remarkably reduced and its distribution is significantly *** separation flows and passage vortices would appear in the rotor because of the swirling inflow,leading to inferior rotor performance.

关键词： swirling inflow pulsating flow CFD turbocharger turbine internal combustion engine

Numerical investigation on unsteady characteristics of ducted fans in ground effect

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中国航空学报:英文版 2023年第9期36卷 79-95页

作者： Yiwei LUO Tianfu AI Yuhang HE Bin XU Yuping QIAN yangjun zhang state key laboratory of automotive safety and energy School of Vehicle and MobilityTsinghua UniversityBeijing 100084China Vehicle Research Center School of Mechanical EngineeringBeijing Institute of TechnologyBeijing 100081China beijing Institute of Technology Chongqing Innovation Center Chongqing 401120China

Ducted fans are widely used in various applications of Unmanned Aerial Vehicles(UAVs)due to the high efficiency,low noise and high *** unsteady characteristics of ducted fans flying near the ground are significant,which may bring stability *** this paper,the sliding mesh technology is applied and the Unsteady Reynolds Averaged Navier-Stokes(URANS)method is adopted to evaluate the influence of ground on the aerodynamic performance of ducted *** time-averaged results show that the ground leads to the decrease of duct thrust,the increase of rotor thrust and the decrease of total *** transient results show that there exist small-scale stall cells with circumferential movements in ground *** stall cells start to appear at the blade root when the height is 0.8 rotor radius distance,and arise at both the blade root and tip when the height drops to *** is found that the unsteady cells rotate between blade passages with an approximate relative speed of 30%-80%of the fan speed,and lead to thrust fluctuations up to 37%of the total *** results are essential to the flight control design of the ducted fan flying vehicle,to ensure its stability in ground effect.

关键词： Computational fluid dynamics Ducted fan Ground effect Thrust fluctuations UAV