Study On The Restriction Of Jet Mode And Structure Of Gas Wave Tube On Refrigeration Efficiency

Basing on the National Natural Science Foundation (51276026), aiming at the defect of the refrigeration mechanism of gas wave refrigerator at present and open questions, the restriction of jet modes of static refrigerator gas wave tube on refrigeration efficiency and the performance of gas wave tube with innovation-type structure is systematically profoundly investigated. Research approaches have theoretical analysis, numerical simulation and experimental study. The relation of the three is mutual supplement and verification. The research results will enrich achievements for foundation task and provide reliable evidences for the declaration of the proprietary intellectual property rights. The main research work and achievements are as following.(1) Through building the calculation model of gas wave tube and applying Realizable k-s turbulence model and finite volume method, the aim is to contrast the refrigeration efficiency of non-ideal jet mode and ideal little duty cycle time-averaged jet mode and reveal the choke point of limiting the improvement of efficiency.The strength of multi-tube time-averaged jet is verified by CFD and experimental research. The study shows that the little duty cycle time-averaged jet mode is effective measure to improve the refrigeration efficiency of the static gas wave refrigerator. The refrigeration efficiency of four tubes type time-averaged jet distribution increases more 40% than that of the two tubes type time-averaged jet distribution and multi-tubes type no time-averaged jet distribution. When the quantities of tube increase to eight, the difference can reach 70%. The experimental results completely verify the rules that the refrigeration efficiency will increase with the decrease of duty cycle. Therefore, the result promotes the arise of the novel external excited jet multi-stage time-averaged oscillation.(2) Analyzing the motion law of waves, aiming at the insufficient of eliminating reflect shock wave for existing gas wave tube, the existing gas wave tube and Innovative dissipative structure gas wave tubes are profoundly theoretically analyzed, simulated by CFD and verified by experimental comparison. When the traditional absorbing wave cavity installed in the end of gas wave tube is shifted to the middle location of gas wave tube, the effect of eliminating reflect shock wave that will be more remarkable. The results made by numerical simulation show that on the basis of the traditional absorbing wave cavity gas wave tube, the second peak refrigeration efficiency of the novel tube can increase 10% and the valley efficiency can increase 15%. The experimental results show the variation tendency between efficiency and frequency is the same as the simulation tendency. The refrigeration efficiency under the second extreme frequency and greater frequency is increased 3%. The valley efficiency is increased more 7%.On the basis of the novel gas wave tube, the gas wave tube of combining the middle restriction wave cavity with terminal absorbing wave cavity is simulated and verified by experiment. It turned out that reflected shock wave is almost eliminated and the dissipation intension of back gas wave tube is intensified. The simulated result show the amplification of the second peak efficiency is almost invariable, the first peak efficiency is increased more 8% and valley efficiency is increased about 10%. The experimental results show that the amplification of the second peak efficiency is almost invariable, the first peak and valley efficiency are increased more 3%. What's more, experiment and simulation show that the fluctuation level of efficiency becomes lower. So the curve between efficiency and frequency shows a flat tendency.(3) The different structures and styles of outlet of static gas wave refrigerator are investigated. It is found that compared to the unilateral and bilateral vertical outlet, the anteverted oblique outlet could do more to reduce short-circuit outflow and kinetic energy loss of jet and increase the exhaustion of cooled gas. The refrigeration efficiency can increase 3% to 4%. When the width of tube and outlet is equivalent, the optimum efficiency can be obtained.