基于光强测量毛细超高压水射流集束性的实验研究

Experimental Study of Ultra-High Pressure Capillary Water Jet Based on Image Intensity

关键词:  超高压水射流  喷嘴结构  湍流  光学测量 

Key words:  Ultra-high pressure water jet  Nozzle configuration  Turbulence  Optical measurement

摘要:

准确划分射流集束段和雾化段是研究射流集束性的前提。设计了一种基于光强定量测量集束性的方法。基于该方法对具有尖锐边缘孔口和类流线型出口流道的喷嘴,在超高压喷射条件下形成的水射流结构形态进行分析,并与直柱型出口流道喷嘴射流对比分析。结果表明:光强测量法能够比较准确地划分射流集束段和雾化段,区分雾化段中核心区和气液混合区；毛细超高压水射流的集束性在雷诺数影响下由喷嘴孔口结构、出口流道结构的综合作用决定；在一定雷诺数范围内,具有尖锐边缘孔口和类流线型出口流道的喷嘴有良好的集束性,当雷诺数达到1.8×10⁴~1.9×10⁴时,射流集束段长度趋于恒定；喷嘴出口流道结构通过气流调节,对射流集束性的影响在高雷诺数下可以忽略,空气动力扰动在高雷诺数下对射流集束性影响程度显著降低。 

Abstract:

In order to study the fluidic beam concentration (FBC) of ultra-high pressure water jet, its intact section and mixture section should be distinguished firstly. A method was developed so that FBC could be measured through images of jets. The experimental nozzle has a sharp-edge orifice and a streamline like exit structure. The jet configuration study under ultra-high pressure based on intensity analysis was presented and was compared with the jets whose nozzle has a right circular cylinder exit structure. The results show that the present method can recognize the intact section and atomization section of the water jets and it can distinguish the core part and the mixture part within the atomization section based on light intensity. The FBC of ultra-high pressure water jet was determined by the Reynolds numbers and the structure of orifice and exit. The water jets from the nozzle with sharp-edge orifice and streamline like exit structure have better FBC within limits, and the FBC of water jets will no longer change when the Reynolds number is over a certain range (18000～19000). The effects of air regulation by exit structure on the FBC are not significant when the Reynolds number is large enough. The jet FBC affected by aerodynamic disturbance will decrease under large Reynolds numbers. 