Suppression of Cavitation Surge in Turbopump With Inducer by Reduced-Diameter Suction Pipe With Swirl Brake

Abstract

Downsizing and high power density of turbopumps are achieved by increasing their rotational speed. Cavitation often becomes a problem while the influence of cavitation will be generally relieved by employing an inducer before the impeller. For general-use turbopumps with inducer, instability-free operation as well as high suction performance are required in wide flow rate range including extremely low flow rate. However, the low frequency and large amplitude of cavitation surge is often be a serious problem even with inducer when operated at very low flow rates. In this study, a reduced-diameter suction pipe (RSP) equipped with swirl brake (SB) was proposed for a suppression device of the inlet backflow as well as of the cavitation surge through removing swirling velocity component. The effectiveness of this device was investigated by CFD and experiments. First, several geometries of RSP with SB were examined by CFD, and it was found that the extension of inlet backflow was stopped at this device provided that the swirl brake had a sufficient radial or axial length. Then, one of the proposed RSP with SB was manufactured, and the experimental evaluation of the effectiveness of this device was conducted. It seemed that RSP with SB could well prevent the extension of inlet backflow. The cavitation surge was completely suppressed even at extremely low flow rates. As a result, the suction performance was also improved at low flow rates.

Spectral Properties of Foams and Emulsions

“…Cavitation in liquids is an interesting phenomenon with substantial impact in engineering, medicine and fundamental physics [74]. Except the association with erosion damage in hydraulic turbomachinery [75], foams generated through cavitation find interesting microfluidics [76], as well as biomedical applications like cell poration [77] and drug delivery [78].…”

Influence of Rotating Speeds and Thermodynamic Effects on LOX Turbopump Performance

“…The finite volume method was used to solve the system of equations in commercial software ANSYS-CFX. Since it is extensively benchmarked for turbomachines, the shear stress transport (SST) turbulence model proposed by Menter et al [47] with automatic wall-treatment was employed to compile the governing equations, similar to Tanaka et al [13] and Chabannes et al [48]. A highresolution scheme was utilized for the advection scheme to achieve robust and accurate solutions.…”

“…Experimental test and numerical simulation are the two main methods that provide an in-depth understanding on this issue [10,11]. Currently, due to the high cost of experimental test and improved accuracy of numerical simulation, the research strategy of preliminary simulation analysis and final experimental verification is generally adopted [12][13][14]. In terms of the operating conditions of centrifugal pumps, the working conditions of a turbopump can be realized by varying the rotational speeds or flow rates.…”