A high-fidelity numerical simulation software (CRUNCH CFD®) predicts the transient performance of flight valve designs, provides design support by supplementing current empirical rules, and diagnoses system anomalies. Currently, transient analysis of valves is difficult to simulate because of the requirement to dynamically deform the grid due to the valve motion. For complex, transient problems such as engine startup or shutdown that also involve dynamic sealing of fluid flow paths due to valve/solid surface contact, it becomes nearly impossible to deform the grid in an automated fashion.

This numerical modeling software will facilitate the simulations of transient valves in an automated fashion without manual intervention. The simulation tool uses the immersed boundary method (IBM) for the analysis of such transient problems with moving solid boundaries. This methodology treats the solid bodies (or valves) as internal “immersed” surfaces within a stationary background grid, and dynamically resolves the portions of this grid that are within the solid and those that are in the fluid regions. For cells that are cut by the valve surface, special treatment is applied to maintain the integrity of the solid surface and apply adequate boundary conditions so as to enable the fluid flow near a solid surface. When the solid body is in motion, its immersed surface cuts through different cells in the grid and thus the solid/fluid regions in the grid are updated dynamically to account for this motion. Since the methodology also allows for the dynamic sealing and opening of flow paths during valve operation, it can potentially enable the simulation of engine startup and shutdown transients in the near future.

Liquid rocket engines that can be “throttled” over a wider operating range will require the use of transient valve designs that can modulate the flow rate based on the operational requirement. This innovation will facilitate the design and high-fidelity analysis of such engines.

This work was done by Chandrasekhar Kannepalli, Ronald Ungewitter, and Ashvin Hosangadi of Combustion Research & Flow Technology, Inc. for Marshall Space Flight Center (MSFC). For more information, contact Ronald C. Darty, Licensing Executive in the MSFC Technology Transfer Office, at This email address is being protected from spambots. You need JavaScript enabled to view it.. Refer to MFS-32978-1.

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This article first appeared in the September, 2014 issue of Software Tech Briefs Magazine.

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