Numerical and experimental investigation of a compressor with active self-recirculation casing treatment for a wide operation range

Abstract

A turbocharger compressor with a wide flow range and a high efficiency is important to the application of advanced clean combustion technologies, such as homogeneous charge compression ignition and low-temperature combustion, in diesel engines. Self-recirculation casing treatment is one of the techniques that can extend the compressor surge margin without much efficiency penalty. The underlying physics of the self-recirculation casing treatment technology were investigated with computational fluid dyamics modeling and bench testing in this study. It is identified that, if the bleed slot of the self-recirculation casing treatment is located upstream of the impeller passage’s throat area, self-recirculation casing treatment improves the surge margin but the throat still limits the maximum flow capacity of the compressor. On the other hand, if the bleed slot of the self-recirculation casing treatment is located at the impeller passage’s throat area, the self-recirculation casing treatment improves the maximum flow capacity but results in a significant compressor efficiency penalty in the low-flow range. An active self-recirculation casing treatment design was proposed. The active self-recirculation casing treatment design extends the compressor flow capacity and improves the surge margin without an efficiency penalty through dual bleed slots with one upstream and the other downstream of the leading edge of the splitter blades. In the choke condition, the upstream bleed slot will be closed; near the surge condition, the downstream bleed slot will be closed. In the middle flow range, both bleed slots are closed. Both the numerical data and the bench testing results show that the maximum flow rate could be extended by about 15% and the surge margin by about 20% without an efficiency penalty. The mechanism of the performance improvement is also numerically studied.

Flow Control Methods and Their Applicability in Low-Reynolds-Number Centrifugal Compressors—A Review

“…. +0.15% + + [170] 2016 Recirculating slots AC 7.4-8.4% +2% +10% [174] 2016 Recirculating slots AC −2.71% +33.05% [169] 2015 Grooves CC ±0% +2.48% + [192] 2015 Injection nozzle CC 1.5% +37% [193] 2015 Injection nozzle CC 1-12% +30% [175] 2015 Injection tube Turbine blade 323,955 0.3-4% Reduction in total pressure loss [194] 2015 Recirculating slots AC − − +5.7% [195] 2013 Recirculating holes CC −1% −2% +10% [196] 2013 Recirculating slots CC 11% ±0% +20% [197] 2013 Recirculating slots CC −1% +17% [197] 2013 Recirculating slots with vanes CC +2% +4% + [198] 2012 Recirculating slots CC up to 13% ±0% + [198] 2012 Recirculating slots with vanes CC up to 17% ±0% + [173] 2012 Recirculating slots CC + [199] 2011 Recirculating holes CC −2 . .…”

Casing Treatment of Centrifugal Compressors

“…This is proved to give a better compressor operability range as compared to the solid shroud compressors. Recently, an increasing amount of research is been carried out on Ported Shroud geometries to compare its performance over the solid shroud geometries [1][2][3]. Several parameters such as port and slot width, their locations, their inclination etc.…”

“…Several parameters such as port and slot width, their locations, their inclination etc. are studied in order to optimize the port-slot geometry [1].Many detailed studies are also done using Particle Image Velocimetry [PIV], which is a powerful tool for turbo machinery investigation, to analyze the aerodynamics leading to stall and eventually to surge [4,5]. …”

Improving the Performance of Centrifugal Compressors by Flow Recirculation

“…They improved the compressor surge line for a high pressure ratio turbocharger compressor having vaned diffuser. Different variations and optimizations of casing treatment can be found in the literature like the work of Hu et al (2016). In this method, the low momentum fluid is removed from the flow path and thus passage blockage is removed and the rest of the flow is allowed to continue the diffusion process.…”