The Experts below are selected from a list of 34809 Experts worldwide ranked by ideXlab platform
Xin Qian Zheng - One of the best experts on this subject based on the ideXlab platform.
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Potential of variable diffuser vanes for extending the Operating Range of compressors and for improving the torque performance of turbocharged engines
Proceedings of the Institution of Mechanical Engineers Part D: Journal of Automobile Engineering, 2017Co-Authors: Qiangqiang Huang, Xin Qian ZhengAbstract:Turbocharging plays a significant role in internal-combustion engines. For engines in the future or for engines Operating at a high altitude, compressors which are able to deliver a high pressure ratio are preferable. However, the poor low-end torque characteristics of turbocharged engines, which are often restricted by the narrow Operating Range of compressors at a high pressure ratio, result in a severe problem for turbocharging. The use of variable diffuser vanes is an effective method to increase the Operating Range, but the potential of an extended Operating Range at a high pressure ratio and improvement in the torque performance of engines is unclear. Nowadays, the pressure ratio of a turbocharger compressor may be only 1?4. Because of the increase in the pressure ratio, estimating the potential is ultimately worthwhile. In this paper the performances of a centrifugal compressor with different diffuser vane angles are investigated, the Range extension and the improvement in the torque performance which benefited from variable diffuser vanes are estimated and the mechanisms for Range extension are revealed. The approach includes steady three-dimensional Reynolds-averaged Navier?Stokes simulations and theoretical analysis. Adjusting the vane angle from ?10° to 10° improves the Operating Range of a compressor from 23.5% (with fixed vanes) to 54.9% at a pressure ratio of 4.8. The Range extension is obtained by utilizing the shifts in the choke line and the surge line. A method of assessing the choking component based on the simulation results is proposed. The diffuser, the flow stability of which was enhanced comparatively by closing it (pivoting the vanes by ?10° and ?5°), contributes mainly to reducing the surge flow. With this Range extension, the improvement in the maximum torque is estimated to be 78%.
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Potential of variable diffuser vanes for extending the Operating Range of compressors and for improving the torque performance of turbocharged engines
Proceedings of the Institution of Mechanical Engineers Part D: Journal of Automobile Engineering, 2016Co-Authors: Qiangqiang Huang, Xin Qian ZhengAbstract:Turbocharging plays a significant role in internal-combustion engines. For engines in the future or for engines Operating at a high altitude, compressors which are able to deliver a high pressure ratio are preferable. However, the poor low-end torque characteristics of turbocharged engines, which are often restricted by the narrow Operating Range of compressors at a high pressure ratio, result in a severe problem for turbocharging. The use of variable diffuser vanes is an effective method to increase the Operating Range, but the potential of an extended Operating Range at a high pressure ratio and improvement in the torque performance of engines is unclear. Nowadays, the pressure ratio of a turbocharger compressor may be only 1–4. Because of the increase in the pressure ratio, estimating the potential is ultimately worthwhile. In this paper the performances of a centrifugal compressor with different diffuser vane angles are investigated, the Range extension and the improvement in the torque performance wh...
Kazutoyo Yamada - One of the best experts on this subject based on the ideXlab platform.
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The Effect of Tip Leakage Vortex for Operating Range Enhancement of Centrifugal Compressor
Journal of Turbomachinery, 2013Co-Authors: Isao Tomita, Masato Furukawa, Seiichi Ibaraki, Kazutoyo YamadaAbstract:Recently, the application of turbochargers is increasing because they are effective in improving fuel consumption of engines. One of the most important turbocharger characteristics is compressor Operating Range, since it has been used in various driving patterns with the advent of variable geometry turbochargers. Owing to the complicated phenomena, such as rotating stall occurring at low flow rate condition, flow analysis is very difficult and details of flow structure have not been fully understood for a long time since the early 1970s. In this study, two compressors with different Operating Range width were investigated with experimental and computational flow analysis. In the compressor with narrow Operating Range, the amplitude of blade passing pressure fluctuation decreases rapidly and rotating stall occurs near surging. On the other hand, in the compressor with wide Operating Range, the blockage by the tip leakage vortex breakdown play a role in stabilizing the flow field and keeping up a high performance even at low flow rates.
Qiangqiang Huang - One of the best experts on this subject based on the ideXlab platform.
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Potential of variable diffuser vanes for extending the Operating Range of compressors and for improving the torque performance of turbocharged engines
Proceedings of the Institution of Mechanical Engineers Part D: Journal of Automobile Engineering, 2017Co-Authors: Qiangqiang Huang, Xin Qian ZhengAbstract:Turbocharging plays a significant role in internal-combustion engines. For engines in the future or for engines Operating at a high altitude, compressors which are able to deliver a high pressure ratio are preferable. However, the poor low-end torque characteristics of turbocharged engines, which are often restricted by the narrow Operating Range of compressors at a high pressure ratio, result in a severe problem for turbocharging. The use of variable diffuser vanes is an effective method to increase the Operating Range, but the potential of an extended Operating Range at a high pressure ratio and improvement in the torque performance of engines is unclear. Nowadays, the pressure ratio of a turbocharger compressor may be only 1?4. Because of the increase in the pressure ratio, estimating the potential is ultimately worthwhile. In this paper the performances of a centrifugal compressor with different diffuser vane angles are investigated, the Range extension and the improvement in the torque performance which benefited from variable diffuser vanes are estimated and the mechanisms for Range extension are revealed. The approach includes steady three-dimensional Reynolds-averaged Navier?Stokes simulations and theoretical analysis. Adjusting the vane angle from ?10° to 10° improves the Operating Range of a compressor from 23.5% (with fixed vanes) to 54.9% at a pressure ratio of 4.8. The Range extension is obtained by utilizing the shifts in the choke line and the surge line. A method of assessing the choking component based on the simulation results is proposed. The diffuser, the flow stability of which was enhanced comparatively by closing it (pivoting the vanes by ?10° and ?5°), contributes mainly to reducing the surge flow. With this Range extension, the improvement in the maximum torque is estimated to be 78%.
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Potential of variable diffuser vanes for extending the Operating Range of compressors and for improving the torque performance of turbocharged engines
Proceedings of the Institution of Mechanical Engineers Part D: Journal of Automobile Engineering, 2016Co-Authors: Qiangqiang Huang, Xin Qian ZhengAbstract:Turbocharging plays a significant role in internal-combustion engines. For engines in the future or for engines Operating at a high altitude, compressors which are able to deliver a high pressure ratio are preferable. However, the poor low-end torque characteristics of turbocharged engines, which are often restricted by the narrow Operating Range of compressors at a high pressure ratio, result in a severe problem for turbocharging. The use of variable diffuser vanes is an effective method to increase the Operating Range, but the potential of an extended Operating Range at a high pressure ratio and improvement in the torque performance of engines is unclear. Nowadays, the pressure ratio of a turbocharger compressor may be only 1–4. Because of the increase in the pressure ratio, estimating the potential is ultimately worthwhile. In this paper the performances of a centrifugal compressor with different diffuser vane angles are investigated, the Range extension and the improvement in the torque performance wh...
Mahendra B. Ghat - One of the best experts on this subject based on the ideXlab platform.
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DC Fault Tolerant Modified Parallel Hybrid Converter with Enhanced Operating Range
2018 IEEE Energy Conversion Congress and Exposition (ECCE), 2018Co-Authors: Siba Kumar Patro, Mahendra B. Ghat, Anshuman ShuklaAbstract:This paper presents a modified parallel hybrid converter (MPHC) for HVDC applications with wide Operating Range and dc-fault tolerant capabilities. A novel control technique is proposed for capacitors voltage balancing of MPHC. The performance evaluations of the proposed converter and its control are carried out using PSCAD/EMTDC for both under- and overmodulation index (MI) Range and also for an HVDC system. Two methods are proposed to make the MPHC tolerant to dc fault. The results obtained confirm the superior performance of the proposed converter over the existing ones. The capacitor size design methodology, loss calculation of the converter and self-excited pre-charging mechanism are also presented.
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Hybrid Series Converter: A DC Fault Tolerant HVDC Converter with Wide Operating Range
IEEE Journal of Emerging and Selected Topics in Power Electronics, 1Co-Authors: Siba Kumar Patro, Anshuman Shukla, Mahendra B. GhatAbstract:A compact, efficient and dc-fault tolerant hybrid series converter (HSC) topology is proposed in this paper for HVDC applications. It contains a parallel and a series chain-link (CL) per-phase. The parallel CL (PCL) supports the dc-link whereas the series CL (SCL) enables the HSC to have enhanced Operating Range and dc fault tolerant capabilities. A new control technique is proposed to control the SCL sub-modules (SMs) capacitor voltage for its entire Operating Range. The performance of HSC and its control technique are evaluated using PSCAD/EMTDC for various conditions. The capability of HSC to work in under-and over-modulation index Range and for HVDC system is examined. Further, the response of HSC during pole-topole dc fault and ac faults are analyzed to substantiate its dc fault blocking and ac fault ride-through capabilities. The results obtained validates that the HSC exhibits superior performance over the existing ones. The SMs capacitor size design methodology in HSC and for other existing topologies are described. The loss calculation of the HSC is carried out to determine its efficiency and is compared with the prominent converter topologies. A threephase 13-level HSC experimental setup is developed to validate its feasibility and also to reconfirm the simulation outcomes.
Yohei Ishizu - One of the best experts on this subject based on the ideXlab platform.
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Enhancement of Centrifugal Compressor Operating Range by Control of Inlet Recirculation With Inlet Fins
Journal of Turbomachinery, 2016Co-Authors: Hisashi Tamaki, Ryuuta Tanaka, Masaru Unno, Satoshi Yamaguchi, Yohei IshizuAbstract:The Operating points of a turbocharger compressor tend to approach or cross its surge line while an engine is accelerating, particularly under low-engine speed conditions, hence the need for an acceptable surge margin under low compressor-speed conditions. A method shifting the stability limit on a compressor low-speed line toward a lower flow rate is expected and inlet recirculation is often observed in a centrifugal compressor with a vaneless diffuser near a surge and under a low compressor-speed condition. First, examples of inlet recirculation were introduced in this paper, whereupon the effect of inlet recirculation on compressor characteristic was discussed by 1D consideration and the potential shown for growth of inlet recirculation to destabilize compressor operations. Accordingly, this study focused on suppressing the effect of inlet recirculation on compressor characteristics using small fins mounted in a compressor-inlet pipe, and examining whether they enhance the compressor Operating Range under low-speed conditions. Small fins are known as inlet fins in this paper. According to test results, they showed great promise in enhancing the compressor Operating Range during inlet recirculation. Besides, attempts were also made to investigate the qualitative effect of inlet fins on flow fields using computational fluid dynamics (CFD) and the disadvantages of inlet fins were also discussed.
