Visualization and velocity analysis of a high-speed modulated water jet generated by a hydrodynamic nozzle

Abstract

• The new hydrodynamic nozzle generating self-excited water jet was tested. • The jet visualisation and determination of velocity fields was investigated. • High-pressure water flow conditions were monitored. • Knowledge of the jet velocity fields allow optimise flow numerical model. This paper deals with visualization and velocity analysis of a self-excited water jet generated by a designed prototype of hydrodynamic nozzle. The high-speed camera in combination with four high-energy pulsed LED lights and the particle image velocimetry method were tested. The influence of water pressure on the jet shape, velocity field and frequency of the self-excited jet was studied. The designed diagnostic water line consisting of pressure sensors and a turbine flowmeter was used for flow monitoring during experimental flow visualization. It was observed that the used optical equipment is suitable for velocity-frequency investigation up to 40 MPa with the maximal jet velocity 247 m/sec, 4.5 kHz oscillation frequency. The overall speed dependence of velocity on the distance downstream from the nozzle outlet (0–100 mm) decreases by 13–15% for tested pressure levels. Oscillation of self-excited jet in the 10–40 MPa pressure range is changing in range 2.5–4.5 kHz.