Abstract
It is known that cavitating flow characteristics and instabilities in inducers can greatly impact the safety and stability of a liquid rocket. In this paper, step casing optimization design (Model OE and Model AE) was carried out for two three-bladed inducers with an equal (Model O) and a varying pitch (Model A), respectively. The unsteady cavitation flow field and accompanied instabilities were studied via numerical simulations. Reductions of the cavity size and fluctuation were observed in cases with a step casing. A significant difference in cavity structures was seen as well. Referring to the pressure distributions on the blades and details of the flow field, the mechanism of cavitation suppression was revealed. This work provides a feasible and convenient method in engineering practice for optimizing the characteristic of the cavitating flow field and instabilities for the inducer.
Highlights
In hydraulic systems of liquid rocket engines, turbopumps are the main hydraulic components that convey fuel and oxidizers
Unlike the equal pitch inducer, a significant difference in cavity structures were seen in the varying pitch inducer when the step casing was applied
As for Model OE and AE, with lower velocity and higher leakage flow rates, the clearance flow tended to interact with the main flow in a closer region
Summary
In hydraulic systems of liquid rocket engines, turbopumps are the main hydraulic components that convey fuel and oxidizers. Installing an inducer at the upstream of the main pump is a common solution to mitigate the aforementioned effects. Great efforts including inducer impeller optimization and casing modifications were made to alleviate the influences of cavitation and its associated instabilities. Considering the manufacturing convenience and the degree of overall structural change, casing modification, especially step casing design, has been widely studied [10,11,12,13,14]. Kamijo et al [4] designed five casings with upstream/trailing edge enlargements and proposed a criterion for RC suppression in a LE-7 LOX (Liquid Oxygen) turbopump inducer. Hashimoto et al [10] experimentally illustrated the influence of step casing with an upstream enlargement. Shimagaki et al [15] described the mechanism for Processes 2020, 8, 1103; doi:10.3390/pr8091103 www.mdpi.com/journal/processes
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