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Effect of Self Recirculation Casing Treatment on the Performance of a Turbocharger Centrifugal Compressor

Gancedo, Matthieu
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439305804

Abstract Details

2015, PhD, University of Cincinnati, Engineering and Applied Science: Aerospace Engineering.
Increase in emission regulations in the transport industry brings the need to have more efficient engines. A path followed by the automobile industry is to downsize the size of the internal combustion engine and increase the air density at the intake to keep the engine power when needed. Typically a centrifugal compressor is used to force the air into the engine, it can be powered from the engine shaft (superchargers) or extracting energy contained into the hot exhaust gases with a turbine (turbochargers). The flow range of the compressor needs to match the one of the engine. However compressors mass flow operating range is limited by choke on the high end and surge on the low end. In order to extend the operation at low mass flow rates, the use of passive devices for turbocharger centrifugal compressors was explored since the late 80's. Hence, casing treatments including flow recirculation from the inducer part of the compressor have been shown to move the surge limit to lower flows. Yet, the working mechanisms are still not well understood and thus, to optimize the design of this by-pass system, it is necessary to determine the nature of the changes induced by the device both on the dynamic stability of the pressure delivery and on the flow at the inlet. The compressor studied here features a self-recirculating casing treatment at the inlet. The recirculation passage could be blocked to carry a direct comparison between the cases with and without the flow feature. To grasp the effect on compressor stability, pressure measurements were taken in the different constituting elements of the compressor. The study of the mean pressure variations across the operating map showed that the tongue region is a limiting element. Dynamic pressure measurements revealed that the instabilities generated near the inducer when the recirculation is blocked increase the overall instability levels at the compressor outlet and propagating pressure waves starting at the tongue occurred, different in nature from rotating stall. The flow velocity was also measured at the inlet of the compressor by means of planar PIV measurements. The case without recirculation showed strong back flow occurrence at low MFR on the shroud of the inlet passage due to tip recirculation. With recirculation, this back flow was significantly reduced improving the overall stability. However, with the current recirculation channels design, there is an efficiency penalty and the recirculated flow introduces non-homogeneities in the mixing region. Finally, to explore experimentally the effect of variations of the casing treatment, several different designs were tested. It was seen that modifications of the supporting rib shape impacted the efficiency. Also, improvements on the surge line were obtained with flow reinjection near the inducer in the direction of the main flow at low speeds and with induced counter swirl for all speeds.
Ephraim Gutmark, Ph.D. D.Sc. (Committee Chair)
Shaaban Abdallah, Ph.D. (Committee Member)
Mark Turner, Sc.D. (Committee Member)
250 p.
Aerospace Materials
Turbocharger; Surge; Centrifugal compressor; PIV; Pressure measurements; Experimental

Recommended Citations

Citations

  • Gancedo, M. (2015). Effect of Self Recirculation Casing Treatment on the Performance of a Turbocharger Centrifugal Compressor [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439305804

    APA Style (7th edition)

  • Gancedo, Matthieu. Effect of Self Recirculation Casing Treatment on the Performance of a Turbocharger Centrifugal Compressor. 2015. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439305804.

    MLA Style (8th edition)

  • Gancedo, Matthieu. "Effect of Self Recirculation Casing Treatment on the Performance of a Turbocharger Centrifugal Compressor." Doctoral dissertation, University of Cincinnati, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439305804

    Chicago Manual of Style (17th edition)

ucin1439305804
563
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This open access ETD is published by University of Cincinnati and OhioLINK.