Abstract:A new kind of jet, which is a wallattached oscillating jet produced by a fluidic element, was put forward and is going to be used in a liquid jet gas pump (LJGP). The liquid jet gas pump was vertically installed on a testrig, and then the performance of twentyfour test models with various dimensions was measured and compared with that of the pump with an ordinary straight jet. The results showed that the driving pressure has a significant influence on the performance, but the performance curves exhibit a similar peak pressure ratio h, the maximum flow ratio q and the pump best efficiency η increase with increasing driving pressure. At the same working pressure, the performance curves get more flat as the area ratio of throat to nozzle m is increased, namely, the peak h decreases and the maximum q increases, and the efficiency η gets a maximum at some value of m. This indicates that there is an optimum area ratio m at which the pump has the best efficiency. The best efficiency of a gas pump with an oscillating liquid jet was about 16%, less than that with a normal straight jet, but the two pumps have an approximate gas flow rate suctioned. Note that an oscillating jet needs a larger area ratio m, moreover as the oscillating frequency is increased, the pressure ratio h is improved but still less than the straight jet. At the given working pressure of 300 kPa, an empirical equation for the unsteady performance curve of a LJGP was proposed by best fitting experimental data. The equation might be used to guide the practical application for such a pump.
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