Accession Number : AD0682296

Title :   ON THE RESPONSE OF PRESSURE MEASURING INSTRUMENTATION IN UNSTEADY FLOW. (AN INVESTIGATION OF ERRORS INDUCED BY PROBE-FLOW INTERACTION),

Corporate Author : TORONTO UNIV (ONTARIO) INST FOR AEROSPACE STUDIES

Personal Author(s) : Siddon,Thomas E.

Report Date : JAN 1969

Pagination or Media Count : 96

Abstract : If a fast responding pressure probe of classical 'static' probe geometry is placed in an unsteady flow it will not register the true instantaneous pressure interaction between the probe and the unsteady velocity field gives rise to an error between the measured pressure Pm(t) and the true pressure Pt(t). This error is not always small; it can in some circumstances be larger than the difference between Pt(t) and the ambient pressure. A major objective of the present work was to explore the possibility of correcting Pm(t) instantaneously, through use of an error-compensating probe. A probe configuration was adopted for which the error reduces to a simple form. The probe was devised to measure simultaneously the unsteady components of Pm(t) and Vn(t) over a wide frequency range. Output signals were processed by analogue means to correct out the error term providing an improved estimate of the true unsteady pressure. A series of experiments were conducted in a number of contrived unsteady flows. Major experiments involved a periodic 'rotating inclined nozzle flow' and some typical turbulent flows. The error-compensating scheme was found to be effective, particularly for the specialized rotating inclined nozzle flow. However the measurements in turbulent flows revealed that the correction to root-mean-square pressure fluctuation level was small, generally amounting to less than 20%. (Author)

Descriptors :   (*PRESSURE GAGES, PERFORMANCE(ENGINEERING)), (*TURBULENCE, FLOWMETERS), INTERACTIONS, RESPONSE, NOZZLE GAS FLOW, CORRECTIONS, AERODYNAMIC NOISE, CALIBRATION, CANADA, ERRORS

Subject Categories : Aerodynamics
      Test Facilities, Equipment and Methods
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE