Visualization of oscillating flow in a double-inlet pulse tube refrigerator with a diaphragm inserted in a bypass-tube

Abstract

The double-inlet pulse tube refrigerator that has a diaphragm inserted in a bypass-tube, which enabled it to transmit a pressure oscillation whereas to obstruct a DC gas flow, was manufactured and tested. The oscillating flow behavior inside of the refrigerator was studied by using a smoke-wire flow visualization technique. It was found that if the diaphragm was optimized, the performance would be improved more than that of the refrigerator with a bypass valve due to the increase in the P-V work of the gas and the decrease in the convective heat loss caused by a secondary flow.

Acoustic field modulation in regenerators

“…For example, if an inertance tube is employed as the phase shifter, its dimensions have to be changed many times [11]. At the same time, the flow field imaging techniques such as hot-wire anemometry, particle image velocimetry, or laser Doppler velocimetry are also employed to measure the volume flow, which is an important parameter of an actual acoustic field to know; otherwise, the theoretical and experimental results cannot be compared [12]. The equipment required makes the experiment very complicated and troublesome.…”