Dynamic Characteristics of a Jet Engine Test Facility Air Supply.

摘要

Dynamic response of a scale model of the Aeropropulsion Systems Test Facility (ASTF) air supply ducting was determined experimentally over a frequency range from 20-200 Hz. Blocked lines with no flow and orifice terminated lines with a mean flow were used. The experiments examined the effects of signal input on three different lines and of using different size venturis. Gain and phase were measured upstream of the venturi and at the end of the line. Experimental results were compared with the results of a computer program based on Nichols' theory as modified by Krishnaiyer and Lechner. With few exceptions, the gains were predicted within + or - 5 dB, and phase angles within + or - 10%. This agreement between theory and experiment verified that the theory can be applied successfully to large, complex systems and that the computer program was running properly. The verified program was then applied to the full-scale ASTF air supply and results analyzed. The ASTF results show higher gains at low frequencies and no reduction in the average gain with frequency. This was as expected for the large ASTF ducting, which ranges from 4-22 ft in diameter.