针栓喷注器径向孔形状对喷雾特性影响实验研究

径向孔型针栓喷注器是目前所用的针栓喷注器中广泛应用的构型，径向孔的构型直接影响其喷雾特性，包括空间分布特性和雾化性能。在保持总流通面积和阻塞比（BF）一致的前提下，本文设计加工了4种结构的径向孔型液液针栓喷注器，并通过冷试试验具体研究了径向孔的几何形状及高宽比对喷雾形态、喷雾锥角、喷雾浓度分布特性和雾化性能的影响。采用背景光成像方法观测喷雾的基本形态并计算喷雾锥角，通过相位多普勒技术（PDA）测量喷雾场的分布特性并分析SMD的分布规律。结果表明，圆孔喷注器相比于矩形孔喷注器具有更大的喷雾径向分布范围，且矩形孔的高宽比越高，喷雾锥角越小，喷孔形状对喷雾锥角的影响与射流和液膜的局部相互作用有关。喷孔形状同样影响到喷雾浓度的分布特性。随着高宽比的增加，喷孔数目增多，相邻喷雾单元间的相互作用增强，喷雾上游空心区范围逐渐缩小直至消失。从雾化性能来看，喷孔几何形状的变化对雾化SMD影响较小，但高宽比的增加使喷雾场中SMD的分布更加均匀，有利于雾化性能的提高。

Experimental Research on Effects of Shape of Radial Orifice on Spray Characteristics of Pintle Injector

The radial flow channel of the pintle injector is normally designed as discrete orifices, and the orifice pattern has important impacts on its spray characteristics, including the spatial distribution and atomization performance. Under the constant total flow area and blockage factor (BF), four pintle injectors were designed and studied by cold flow test to investigate the effect of geometric shape and height-to-width ratio of radial orifice on the spray pattern, spray cone angle, spray density distribution as well as atomization performance. High-speed photography was used to visualize the spray development and Phase Doppler Anemometry (PDA) was used to measure the spray distribution and analyse the SMD distribution in the spray field. The results indicate that the spray range of the pintle injector with circular orifices is relatively larger than that with rectangular orifices, and the spray angle decreases with the increasing height-to-width ratio. The effect of orifice shape is attributed to the local interaction of film and jet. The change of orifice shape also has influence on the spray density distribution. With the increase of height-to-width ratio and orifice number, the interaction of neighbouring spray element is strengthened, which lead to the shrinking of the hollow region in the upflow of the spray. As for the atomization performance, the change of geometric shape has little effect on the SMD distribution, but the increase in height-to-width ratio brings more uniform SMD distribution in the spray field, which is beneficial to the atomization process.