Development of an Experimental Data Base to Validate Compressor-Face Boundary Conditions Used in Unsteady Inlet Flow Computations
Dr. MiNos SajbenDr. Donald D. FreundDepartment of Aerospace Engineering and Engineering MechanicsUniversity of CincinnatiFinal Technical ReportResearch Grant Award fromNational Aeronautics and Space AdministrationNASA Lewis Research CenterPenod of Performance: January 1, 1997 to December 31, 1997May 15, 1998
Unsteady Inlet/Compressor Interaction Experiment to Support the Modeling of Compressor-Face Boundary Conditions
Atmospheric disturbances affecting high-speed, air-breathing propulsion systems may induce rapid flow transients. Such processes usually involve strong interactions between the inlet and the engine, and may lead to undesirable or even unacceptable consequences (e.g. inlet unstart, compressor stall or surge). Their reliable prediction requires, in principle, the simultaneous computation of the flow in both the inlet and the compressor. Such computations, while may be feasible in some simplified form [1,2], are too complex to fit into the cost and time constraint of industrial design processes. Current engineering practice is to perform computations for the two components separately, relying on the compressor face boundary conditions (CFBC’s) to represent the engine for the inlet flow predictions, or the inlet for engine calculations.
The application of a transient testing method to the determination of acoustic properties of unknown systems
Abstract A transient testing technique for the determination of matrix parameters of acoustic systems has been developed and presented earlier in two papers by the authors. This paper deals with the application of this rapid testing method to the determination of several acoustic properties of unknown systems. Theoretical expressions for acoustic impedances and reflection factors are presented as functions of measured pressure ratios and known matrix parameters. Excellent results obtained for simple test cases show that the procedure is fast and accurate over at least a 70 dB range. Moreover, the method lends itself to applications with steady mean flow in the system and with either transient or random input acoustic excitation.