EXPERIMENTAL INVESTIGATION TO VALIDATE USE OF CRYOGENIC TEMPERATURES TO ACHIEVE HIGH REYNOLDS NUMBERS IN BOATTAIL PRESSURE TESTING

摘要

An investigation has been conducted in the Langley 1/3-meter transonic cryogenic tunnel to validate the use of cryogenic temperatures to achieve high Reynolds numbers in nozzle boat-tail pressure testing. Tests were conducted at 0° angle of attack and at Mach numbers of 0.60, 0.85, and 0.90 on two wing-body configurations with differing boattail geometries. Test data were obtained by using two different techniques, the cryogenic method and the conventional method, to obtain the same Reynolds number. Later, the test data obtained from the two tech¬niques on boattail pressure coefficient distributions and pressure drag coefficients were com¬pared; results from the comparisons show excellent repeatability for all test conditions and indicate no measurable errors when using cryogenic temperatures to achieve high Reynolds numbers for nozzle boattail pressure testing.