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Experimental Investigation of Roto-Stator Interaction in Diffuser Pumps

Arndt, Norbert Karl Erhard (1988) Experimental Investigation of Roto-Stator Interaction in Diffuser Pumps. California Institute of Technology , Pasadena, CA.

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The interaction between impeller blades and diffuser vanes in diffuser pumps was investigated. Steady and unsteady pressure measurements were made on the diffuser vanes and on the front shroud wall of a vaned and a vaneless diffuser. Two different impellers were used, one half of the impeller of the double suction pump of the HPOTP (High Pressure Oxygen Turbopump) of the SSME (Space Shuttle Main Engine), and a two-dimensional impeller. The measurements were made for different flow coefficients, shaft speeds, and radial gaps between the impeller blades and the diffuser vanes (1.5% and 4.5% of the impeller discharge radius for the impeller of the HPOTP, and 5% and 8% for the two-dimensional impeller). The vane pressure fluctuations were larger on the vane suction than on the vane pressure side attaining their maximum value, of the same order of magnitude as the total pressure rise across the pump, near the leading edge. The resulting lift on the vane, both steady and unsteady, was computed from the pressure measurements at mid vane height. The magnitude of the fluctuating lift was found to be larger than the steady lift. For the impeller of the HPOTP, pressure measurements on the front shroud of a vaned and a vaneless diffuser showed that the front shroud pressure fluctuations increased with the presence of the diffuser vanes. For the two-dimensional impeller, also unsteady impeller blade pressure measurements were made. The largest blade pressure fluctuations, of the same magnitude as the large pressme fluctuations on the vane suction side, occurred at the blade trailing edge. However, the dependence of those pressme fluctuations on the flow coefficient was found to be different; on the vane suction side, the fluctuations were largest for maximum flow and decreased with decreasing flow coefficient, whereas at the blade trailing edge, the fluctuations were smallest for maximum flow and increased with decreasing flow coefficient. Increasing the vane number resulted in a significant decrease of the blade pressure fluctuations. Lift, vane and blade pressure, and front shroud pressure fluctuations decreased strongly with increasing radial gap.

Item Type:Report or Paper (Technical Report)
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Additional Information:©1988 Norbert Karl Erhard Arndt. Report No. 249.7 on Contract NAS 8-33108. Thesis by Norbert Karl Erhard Arndt In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy. I would like to express my most smcere gratitude to my advisor, Professor A.J. Acosta, whose guidance and advice were irreplaceable during this work. I would also like to thank Professors C. E. Brennen and T. K. Caughey for their continued interest in this research. Special thanks to Mike Gerfen who machined the measurement devices and most of the other parts required for this experimental investigation. I am also thankful to George Lundgren and his team for the machining done during the initial part of this work. The help of fellow graduate student Ron Franz in the course of the experiment was much appreciated. Furthermore, I want to acknowledge the assistance provided ·by Scott Miskcovish. I also want to express my gratefulness to many other people, even if they are not mentioned here, who contributed in different ways to this research. I very much appreciated the financial support of the Rotary Foundation of Rotary International during my first year as a graduate student at Caltech. I would also like to give grateful acknowledgements for the financial support for my and for this research to NASA's George C. Marshall Space Flight Center. In addition, I want to express my thanks to the George C. Marshall Space Flight Center and to the Rocketdyne Division of Rockwell International for providing one half of the double suction pump impeller of the High Pressure Oxygen Turbopump of the Space Shuttle Main Engine for testing during the experiment. Last, but not least, I thank my parents and my sister for the support, the understanding and the encouragement they have given to me.
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Rotary Foundation of Rotary InternationalUNSPECIFIED
NASA's George C. Marshall Space Flight CenterUNSPECIFIED
Record Number:CaltechAUTHORS:20140110-160258397
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:43322
Deposited On:11 Jan 2014 00:31
Last Modified:03 Oct 2019 06:06

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