Development and Validation of a Hybrid-Computer Simulator for a Transonic Cryogenic Wind Tunnel

SUMMARY Experience during the past 6 years of operation of the Langley 0.3-Meter Transonic Cryogenic Tunnel has shown that there are problems associated with the operation and control of such tunnels. One problem has been an inability to provide long-term accurate control of test parameters. Additionally, the time required for transition from one test condition to another has proven to be excessively long. Due to the high degree of process cross-coupling between the independent control variables, man-in-the-loop operation has proven to be much less efficient than desirable in terms of liquid-nitrogen and electrical- power usage. For these reasons, studies have been undertaken at the Langley Research Center to model the cryogenic-wind-tunnel process, to validate the model by the use of experimental data, and to construct an interactive tunnel simulator with the validated model. Additionally, this model has been used