A Laboratory Framework for Synchronous Near/Far-Field Acoustics and MHz PIV in High-Temperature, Shock-Containing, Jets

Abstract

This paper describes the experimental study of the noise generating characteristics of high-temperature, shock-containing jets emanating from conic-section, converging-diverging (C-D) nozzles. Conic C-D nozzles consist of two conic sections, one contracting and the other expanding, joined to form a supersonic nozzle with a very sharp radius of curvature at the nozzle throat. An experiment is conducted in which temporally resolved flow-field measurements are acquired simultaneously with near-field and far-field acoustics to allow investigation of the turbulence associated with noise generation. The MHz rate PIV system and its synchronization with acoustic measurements is described along with methods for data analysis. General acoustic results are presented to characterize the spectral content present, and preliminary results on the measured turbulence structures are discussed.

Localization of Acoustic Sources in Shock-Containing Jet Flows Using Phased Array Measurements

“…To this end, we shall examine a nozzle that consists of a straight walled convergent-divergent section, which we shall refer to as the conic nozzle; the interested reader is referred to Murray et al 9 for nozzle geometry details. Based on the throat-to-exit area ratio, the conic nozzle has a prescribed "design" operating Mach number of M j = 1.74.…”

“…The LES/FW-H codes described here have been extensively used for the prediction of jet noise for a wide variety of subsonic and supersonic jets in both free and impinging jet configurations. [20][21][22] In order to supplement the CFD computations, some experimental phased array tests were conducted in the Anechoic Jet Laboratory (AJL) at the University of Mississippis National Center for Physical Acoustics; facility details can be found in Murray et al 9 This phased array system consists of 32 exponentially spaced Kulite pressure transducers (type XT-140, dynamic range = 0-100 psia), mounted on a stainless steel rod. This array was positioned 60.96 cm (24 inches) below the nozzle exit and offset 7.64 cm (2.94 inches) in the axial direction; the downstream end of the rod was inclined at an angle of 15 0 to the nozzle axis.…”

Toward Active Control of Noise from Hot Supersonic Jets

“…Perform high-fidelity HRLES simulations of this configuration, and obtain adequate time-resolved data on the ADS (as dictated by the results of the previous item). 4. Using FW-H equations, propagate the acoustics on the ADS to microphone locations on the linear array that was used in the experimental measurements.…”

Toward Active Control of Noise from Hot Supersonic Jets

“…A more thorough review of these measurements can be found in Murray et al (2012) 12 who showed the effect of a ceuterbody and faceted internal geometry on the near and far-field pressure. In particular, the center-body was found to increase the broadband shock noise signature registered by both near and far-field microphone arrays located at steep and sideline angles to the jet axis.…”

“…Alternative approaches, based on vortex sound theory, have also been proposed whereby the role of vorticity is more explicit in the formulation. This began with the pioneering work of Powell (1964) 13 and Möhring (1978) 11 which has since transcended to the recent articles by Schräm & Hirschberg (2003).…”