NASA SBIR 01-1 Solicitation

TECHNICAL ABSTRACT (LIMIT 200 WORDS)
The proposed innovation is the development of a compressible gas/liquid framework to simulate cavitation in cryogenic liquid rocket pumps. The generalized compressible framework will allow for the specification of variable thermodynamic properties and physical equations-of-state appropriate to cryogenic working fluids. Furthermore, the acoustics within a multi-phase gas/liquid mixture will be modeled rigorously, allowing for the simulation of interactions between pressure fluctuations and the cavitation process at different frequencies. The model will be implemented within an unstructured numerical framework that will effectively deal with complex geometries and resolve flowfield features using local grid adaption features. In particular, the proposed CFD tool is expected to improve modeling capabilities for inducers that operate at low pressures and high rotational speeds. These flow conditions make inducers susceptible to cavitation instabilities, which have the potential to generate large unsteady forces and reduce engine durability. Most current CFD tools for simulating cavitating flows have originated from incompressible formulations and have difficulty in modeling unsteady phenomena in multi-phase mixtures. With the inclusion of appropriate physical sub-models, the proposed innovation has the potential to be an important and useful tool in the analysis and design of liquid rocket turbopumps.

POTENTIAL COMMERCIAL APPLICATIONS
Empirical correlations and 1-D analyses currently used for turbomachine design are remarkably successful at design conditions but are less reliable at off-design conditions, when unsteady flow, coupled with cavitation, can generate potentially damaging pressure fluctuations and vibrations. Most current CFD tools for pump analyses have been derived from incompressible formulations and are inadequate for these complex flows. To address these deficiencies, the commercial CFD tool resulting from the proposed Phase I and subsequent Phase II efforts will have a generalized compressible formulation with temperature effects. The cavitation model will be implemented within our commercial code CRUNCH, which has an unstructured framework and is ideal for complex turbomachine geometries. This tool may be used with current design procedures to either refine preliminary designs or correct potentially anomalous behavior in existing designs. A broad market exists for this commercial product, including companies that are currently involved in designing space propulsion systems, as well as designers of high-energy industrial pump systems. Such pumps must perform at off-design conditions over extended periods, making it critical that cavitation effects be eliminated or mitigated.

NAME AND ADDRESS OF PRINCIPAL INVESTIGATOR (Name, Organization Name, Mail Address, City/State/Zip)
Ashvin Hosangadi
Combustion Research and Flow Technology,
174 North Main Street, POB 1150
Dublin , PA   18917 - 2108

NAME AND ADDRESS OF OFFEROR (Firm Name, Mail Address, City/State/Zip)
Combustion Research and Flow Technology,
174 North Main Street, POB 1150
Dublin , PA   18917 - 2108