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

Open Access
Doller, Andrew Jonathan
Graduate Program:
Doctor of Philosophy
Document Type:
Date of Defense:
October 12, 2004
Committee Members:
  • Anthony A Atchley, Committee Chair
  • Philip John Morris, Committee Member
  • Robert Mitchel Keolian, Committee Member
  • Victor Ward Sparrow, Committee Member
  • acoustic
  • flows
  • minor losses
  • thermoacoustic
  • stirling
  • resonators
  • junction
Steady flow engineering handbooks like Iidelchik 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 degree, 45 degree and 25 degree 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 degree 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 degree, pressure to the 3.76 for the 45 degree and pressure to the 4.48 for the 25 degree. Common among all resonators, blowing acoustic half--cycle minor losses (K_B) are excited at lower amplitudes than the suction half--cycle (K_S) minor losses. Data collected for the 90 degree junction shows K_B reaches an asymptotic value 40% greater than suggested by Idelchik for steady flow. Although, values for K_B for the conical junctions and K_S for 90 degree junction agree with Idelchik, the slopes of the data do not suggest an asymptotic value is reached.