Acoustic minor losses in high amplitude resonators with single-sided junctions

by Doller, Andrew J.

Abstract (Summary)
Steady flow engineering handbooks like Idelchik20 do not exist for investigators interested in acoustic (oscillating) fluid flows in complex resonators. Measurements of acoustic minor loss coefficients are presented in this dissertation for a limited number of resonator configurations having single-sided junctions. While these results may be useful, the greater purpose of this work is to provide a set of controlled measurements that can be used to benchmark computational models of acoustic flows used for more complicated resonator structures. The experiments are designed around a driver operating at 150 Hz enabling acoustic pressures in excess of 10k Pa in liquid cooled, temperature controlled resonators with 90?, 45? and 25? junctions. These junctions join a common 109 cm long 4.7 cm diameter section to a section of 8.4 mm diameter tube making two sets of resonators: one set with a small diameter length approximately a quarter-wavelength (45 cm), the other approximately a half–wavelength (112 cm). The long resonators have a velocity node at the junction; the short resonators have a velocity anti–node generating the greatest minor losses. Input power is measured by an accelerometer and a pressure transducer at the driver. A pressure sensor at the rigid termination measures radiation pressure from the driver and static junction pressure, as well as the acoustic pressure used to calculate linear thermal and viscous resonator wall losses. At the largest amplitudes, the 90? junction was found to dissipate as much as 0.3 Watt, 1/3 the power of linear losses alone. For each junction, the power dissipation depends on acoustic pressure differently: pressure cubed for the 90?, pressure to the 3.76 for the 45? and pressure to the 4.48 for the 25?. Common among all resonators, blowing acoustic half–cycle minor losses (KB) are excited at lower amplitudes than the suction half–cycle (KS) minor losses. Data collected for the 90? junction shows KB reaches an asymptotic value 40% greater than suggested by Idelchik20 for steady flow. Although, values for KB for the conical junctions and KS for 90? junction agree with Idelchik20, the slopes of the data do not suggest an asymptotic value is reached. iii
Bibliographical Information:


School:Pennsylvania State University

School Location:USA - Pennsylvania

Source Type:Master's Thesis



Date of Publication:

© 2009 All Rights Reserved.