Velocity measurements technique and structure study of high pressure water jet by high speed LIF-PTV

In recent years, high pressure water jet for the soil improvements is one of the most important applications of water jet under high pressure and high liquid flow rate. The jet pressure reaches up to 30 - 200 MPa and sometimes the jet velocity exceeds the super sonic. In order to improve the efficiency and the performance of jet grouting, it is very important to clarify the hydrodynamic structure of water jet under high pressure and high flow rate. However, the fundamental researches on this subject are quite insufficient both analytically and experimentally because of its technical difficulty. In particular, the measurement system for the water jet velocity with high velocity and high flow rate has almost been carried out. In this study, the velocity measurements technique for the combination of Laser Induced Fluorescence (LIF) and Particle Tracking Velocimetry (PTV) was investigated. The high-wattage double pulse Nd:YAG laser equipment as a light source and super sensitive CCD photo detector with image intensifier and with fast shutter gate make it possible to capture precisely a couple of pictures of the high speed water jet. We used Rhodamine B as fluorescent particles. We could obtain the velocity profiles for the high speed water jet. (author)