Abstract:For study the effects of air velocity，air temperature，aperture size and opening mode on the uniformity of differential pressure precooling that set up the test-bed，the influence of the four factors on the uniformity of cooling were analyzed by means of mixed orthogonal experimental analysis.The results showed that：the greater air supply speed and the higher air supply temperature caused the good precooling uniformity effect，which the evenness degree was the lowest value in the process of precooling.For circular openings，the greater aperture size，the better uniformity.For elliptical apertures，the smaller aperture size，the better uniformity.When the aperture was different，the uniformity change process was similar，and the peak value of evenness degree appeared at the same pre-cooling time （the location where the peak appears was the same）.For different factors of air velocity，air temperature，aperture size and opening mode，the evenness value increased first and then decreased.For different air velocity，air temperature，aperture size and aperture opening mode，the order of the degree of influence on uniformity was air temperature，air velocity，aperture size and opening mode.