Abstract：In order to study the characters of self-priming irrigation pumps′ jet nozzles,fluid mechanics principles were used to derive the resistance coefficients and flow coefficients of self-priming irrigation pump.Four different jet nozzles were designed.By calculating the resistance coefficients and flow coefficients,change laws of coefficients with different outlet diameters were obtained.Four self-priming irrigation pumps with four jet nozzles were tested by the test-bed.Combined with the results of experiments and change laws of coefficients,the influences of resistance coefficients and flow coefficients on self-priming capability were studied.The results show that resistance coefficients decrease and flow coefficient increase with the increasing jet nozzle outlet diameters.At the same time,self-priming time was shortened.But the self-priming capability deteriorates with the weakening of jet entrainment effect in certain extent.
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