Experimental verification of a two-sensor acoustic intensity measurement in lossy ducts

Abstract

Two-sensor method proposed by Fusco et al. ["Two-sensor power measurements in lossy ducts," J. Acoust. Soc. Am. 91, 2229-2235 (1992)] is a novel technique that determines acoustic intensity of a gas column in a wide duct from measurements of pressure based on the boundary layer approximation. For further development of this method, its validity is experimentally tested through comparison with the direct method measuring the pressure and the velocity simultaneously, and its formulation is modified to include the narrow duct range where the duct radius is smaller than the viscous boundary layer thickness of the gas. It is shown that the modified two-sensor method enables quick and accurate evaluation of the acoustic intensity seamlessly from narrow to wide duct ranges.

Measurement of Heat Flow Transmitted through a Stacked-Screen Regenerator of Thermoacoustic Engine

“…From the pressure amplitudes and phases obtained with a 24 bit fast Fourier transform analyzer (DS-3100; Ono Sokki Co. Ltd., Yokohama, Japan), we evaluated the acoustic pressure field p(x) = Re [P(x)exp (iωt)] and the velocity field u(x) = Re [ U(x) exp (iωt)] in the 40-mm tube using the two-sensor method [26,27]. The complex amplitude V of the cross-sectional average velocity in the hot end of the regenerator was derived as V = U H /φ from the continuity of volume velocity, where subscript H denotes the location at the hot end of the tube.…”

“…Equation (11) is obtained from Equation (27) of Reference [22] by introducing complex notation for T and by replacing the heat transfer coefficient h with h = 4kNu/d h while using thermal conductivity k of the gas. The heat flow can be estimated by inserting T Nu into Equation (8) and by then using Equation (7).…”

Long-Term Drive in Loop-Tube Using Solar Heat Energy -Basic Study for Practical Use of Thermoacoustic Cooling System-

“…Pressure sensors (PCB Piezotronics Inc.) were set on this system wall to measure the sound pressure in the loop-tube. The sound pressure, the phase difference between the pressure and particle velocity, and the amount of sound intensity in this system were calculated using a two-sensor power method [9,10] with pressure measurement results. Figure 3 depicts the distribution of sound intensity in the loop-tube measured in August.…”

Design and Construction of a Standing-Wave Thermoacoustic Engine with Heat Sources Having a Given Temperature Ratio

“…( 2 ) By using the obtained stability limit condition and linear acoustic theory (10), (11) , the acoustical pressure and velocity at the hot end of the stack are calculated as functions of r stack , L stack , and L c.s. .…”