Session: 7.2.1 - Cavitation I

Paper Number: 170168

170168 - Unsteady Eulerian Multiphase Analysis of a Cavitating Turbopump Inducer 

Abstract: 

Cavitation is a fundamental fluid dynamic phenomenon that occurs in liquid pumps.  Cavitation can create instability, damage, and performance degradation.  Over the past 30 years, Computational Fluid Dynamics (CFD) has been used to assess cavitation in axial, mixed flow, and centrifugal pumps.  The numerical model that has been primarily used is a Volume of Fluids (VOF) model, such as the Rayleigh-Plesset and Schneer-Sauer models.  These models have generally not considered the thermal effects of cavitation.  Boiler feed pumps and rocket turbopumps often employ fluids at temperature that have a pronounced energy transfer from the liquid to the vaporized gas, creating a localized reduction in temperature, thus creating a reduction in the Net Positive Suction Head (NPSH) of the pump, facilitating a greater range of application of the pump. In 1967, Paul Cooper developed a non-dimensional parameter designated the cavitation or vaporization parameter to determine whether or not a pump would exhibit a thermal effect.  Pumps operating with cold water exhibit no thermal effect, while hydrogen turbopumps have often operated with an additional NPSH of 80 meters.  The correct assessment of thermal cavitation is necessary to design and optimize these cavitating turbomachines.

This presentation proposes to demonstrate the effectiveness of using an advanced unsteady Eulerian multiphase CFD solver to assess the thermal effect in a cavitating axial inducer that has been designed and tested by NASA in the 1970’s.  The inducer has been tested over a variety of flow coefficients and temperatures.  This presentation will show the results of the inducer over a standard flow coefficient operating at a variety of temperatures.  The results of the CFD analyses will be compared to the experimental results and the flow visualizations will show the impact on temperature increase on the structure of the resulting cavitation in the body of the inducer.  It is hoped that this method will provide a superior method of assessing the thermal effects of cavitation compared to existing empirical models and reducing the number of prototype tests that must be conducted to assess the overall performance of new pump designs.

Presenting Author: Edward Bennett Mechanical Solutions, Incorporated

Presenting Author Biography: PhD, Fluid Mechanics, The Johns Hopkins University, 42 years experience in the design analysis and optimization of turbomachinery. Awarded 2009 ASME Pump Technology Award and the 2016 ASME Fluids Engineering Award. 2 term Associate Editor of the ASME Journal of Fluids Engineering. Presently serving as the Vice President of Fluids Engineering and Turbomachinery Design for Mechanical Solutions, Incorporated in Whippany, New Jersey.