Investigations on Various Types of Hydraulic Jumps

Abstract

Liquid jet impingement features numerous applications such as jet cooling, jet rinsing, liquid atomization, and chemical reactors. The hydraulic jumps obtained due to normal, oblique, and upward impingement of a free liquid jet of water and ethylene glycol on a stationary horizontal plate are numerically simulated for the prediction of the jump profiles by applying conservation of mass and momentum equation using the volume of fluid (VOF) method. The jump profiles have been acquired experimentally and numerically for different jet inclination angles, plate inclination angles, volume flow rates of liquids, and viscosities of the liquids and are compared with the available theoretical models. The flow fields of impinging liquid jets, due to its inclination, are examined from both numerical and experimental viewpoints. newlineCircular hydraulic jump (CHJ) formed due to normal impingement of water jet and ethylene glycol jet on the horizontal target plate is numerically simulated for the prediction of the radius of the jump and also for the liquid film thickness of the radially spreading flow. The time study of stability and evolution of CHJ is carried out experimentally and computationally. The value of the Froude number measured immediately after the hydraulic jump is observed to be constant and is independent of the kinematic viscosity and flow rate of the liquid. CHJ is also investigated numerically and experimentally by making a small hole at the impingement region of the horizontal target plate such that the central core of the impinging liquid jet gutters out through the hole. The effect of this reformed impingement zone flow is detected to be inconsequential as far as the radial position of the jump and outer Froude number is concerned. newlineIn case of an oblique impingement of the liquid jet on a horizontal flat plate, the stagnation point shifts towards the upstream side of the flow. The stagnation shift (horizontal distance between the geometrical center of the elliptical impingement zone and the stagnation point) is experimentally and numerically captured. newlineThe radius of this radially spreading thin layer due to upward impinging jet on a horizontal surface is observed to be higher than the radius of hydraulic jump obtained from the downward-facing jet over the same surface. The effect of viscosity and volume flow rate of the liquid on the radial spread of thin-film under these conditions is investigated computationally and experimentally. newlineVII newlineThe flow field and the resulting profiles of the jumps, due to normal and inclined water jets impinging on vertical and inclined plates, have been investigated experimentally. newlineThe thin and thick film interactions between hydraulic jumps due to two orthogonal adjacent impinging liquid jets have been investigated analytically and experimentally. The area enclosed by the jumps is predicted using a simple model developed using geometrical features of the flow. newlineThe internal hydraulic jumps in two-phase air-water flow in a suddenly expanding rectangular duct in a horizontal position are carried out experimentally and numerically. The numerical findings are observed to be in good agreement with experimental ones. newline