Abstract: In the present paper, the reflected shock wave absorbing effect and its influence on the performance of thermal separator are investigated by means of a single-tube set-up.In the experiments, the shock wave absorber is a short tube whose relative diameter D/d is 5.7 and relative length l/d is 9.0, the relative length of the oscillatory L/d is from 107 to 730. The expansion ratio is from 2.0 to 6.0 and the exciting frequency is from 30 to 200 Hz. The experimental results show that the reflected shock wave is eliminated effectively as L/d＜400 while the absorber is mounted at the closed end of the tube, but when L/d＞400, it makes no difference to mount the absorber anywhere because the energy of the reflected shock wave is exhausted by the viscosity and friction of the gas inside the tube. Absorbing the reflected shock wave has great effect on the performance of thermal separator, e.g. the refrigeration efficiency is increased significantly, the optimal exciting frequency is decreased, the tube length can be shortened, the varying operating mode of the thermal separator can be improved, etc. When the tube is relatively short, the refrigeration efficiency is increased with the tube length, but when the tube length is increased to some value, the result is just the contrary. The recommended optimal tube length L/d is 200—350 for the tube without absorber and 150—250 for the tube with absorber. There exists a number of peak values of refrigeration efficiency when the exciting frequency is increased and the optimal exciting frequency is equal to the first, the second, and the third peak oscillatory frequency respectively when the tube length is L/d≤267， 267＜L/d≤502, L/d＞502. An optimal parameter matching relationship, which can be used to predict the value of the optimal exciting frequency, is derived in this paper.

Key words:

热分离器, 直接膨胀制冷, 振荡管, 反射激波

摘要： 在膨胀比ε=2～6、振荡管长径比L/d=107～730、射流激励频率f=30～200 Hz范围内，探讨了截面突扩型激波吸收器的消波效果及其对热分离器性能的影响.结果表明：在振荡管末端安装截面突扩短管可有效减弱管内反射激波强度，但当L/d≤107时则不能完全吸收反射激波；吸收管内反射激波，可提高制冷效率，降低最佳射流激励频率值，缩小热分离器体积及改善机器的变工况性能.建立了在安装激波吸收器时振荡管参数间的最佳匹配关系，利用该关系式可以预测热分离器最佳射流激励频率的大小.

关键词:

热分离器, 直接膨胀制冷, 振荡管, 反射激波