Estimating maximum instantaneous distortion from inlet total pressure rms and PSD measurementsAn inexpensive method is developed to determine the extreme values of instantaneous inlet distortion. This method also provides insight into the basic mechanics of unsteady inlet flow and the associated engine reaction. The analysis is based on fundamental fluid dynamics and statistical methods to provide an understanding of the turbulent inlet flow and quantitatively relate the rms level and power spectral density (PSD) function of the measured time variant total pressure fluctuations to the strength and size of the low pressure regions. The most probable extreme value of the instantaneous distortion is then synthesized from this information in conjunction with the steady state distortion. Results of the analysis show the extreme values to be dependent upon the steady state distortion, the measured turbulence rms level and PSD function, the time on point, and the engine response characteristics. Analytical projections of instantaneous distortion are presented and compared with data obtained by a conventional, highly time correlated, 40 probe instantaneous pressure measurement system.
Document ID
19760027295
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Melick, H. C., Jr. (LTV Aerospace Corp. Dallas, TX, United States)
Ybarra, A. H. (LTV Aerospace Corp. Vought Systems Div., Dallas, Tex., United States)
Bencze, D. P. (NASA Ames Research Center Moffett Field, Calif., United States)