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为了研究敞口式离心喷嘴内部流动特性,包括填充过程及结构参数和工作参数对流量系数及液膜厚度的影响,对7个不同切向孔直径及长径比的喷嘴展开了试验和数值模拟。采用高速背光对透明敞口式离心喷嘴进行光学测量,喷注压降从0.1~0.8MPa,结合数值模拟研究了旋流室内液膜的填充过程,捕获了空心涡形成及发展过程,得到了敞口式离心喷嘴液膜厚度和流量系数随结构参数及工作参数的变化规律。研究发现几何特性参数越高,液膜厚度、流量系数和质量流量越低;低压降时流量系数随喷注压降升高而略微增加,当喷注压降达到临界值0.4MPa后,流量系数和液膜厚度几乎不变,最大波动分别为1.1%和6%。综合考虑工作参数及结构参数,拟合流量系数及质量流量经验公式,最大偏差皆不超过10%。
In order to study the internal flow characteristics of an open-ended centrifugal nozzle, including the filling process and the influence of structural parameters and working parameters on the flow coefficient and the thickness of the liquid film, experiments and numerical simulations were carried out on seven nozzles with different diameters and aspect ratios . The high-speed backlight was used to measure the optical properties of the transparent open-ended centrifugal nozzle. The jet pressure drop was 0.1 ~ 0.8MPa. The filling process of the liquid film in the swirling chamber was studied by numerical simulation. The formation and development of hollow vortex were captured. The variation of liquid film thickness and flow coefficient with the structural parameters and working parameters of a ported centrifugal nozzle. The results show that the higher the geometrical parameters, the lower the liquid film thickness, the flow coefficient and the mass flow rate. The flow coefficient increases slightly with the increase of jet pressure drop at low pressure drop. After the jet pressure drop reaches the critical value of 0.4 MPa, And liquid film thickness almost unchanged, the maximum fluctuations were 1.1% and 6%. Considering the working parameters and structural parameters, fitting the flow coefficient and mass flow empirical formula, the maximum deviation is not more than 10%.