Modelling of hydrodynamic cavitation with orifice: Influence of different orifice designs

Abstract

Hydrodynamic cavitation (HC) may be harnessed to intensify a range of industrial processes, and orifice devices are one of the most widely used for HC. Despite the wide spread use, the influence of various design and operating parameters on generated cavitation is not yet adequately understood. This paper presents results of computational investigation into cavitation in different orifice designs over a range of operating conditions. Key geometric parameters like orifice thickness, hole inlet sharpness and wall angle on the cavitation behaviour is discussed quantitatively. Formulation and numerical solution of multiphase computational fluid dynamics (CFD) models are presented. The simulated results in terms of velocity and pressure gradients, vapour volume fractions and turbulence quantities etc. are critically analysed and discussed. Orifice thickness was found to significantly influence cavitation behaviour, with the pressure ratio required to initiate cavitation found to vary by a factor of 10 for orifice thickness to diameter (l/d) ratios in the range of 0-5. Inlet radius similarly has a pronounced effect on cavitational activity. The results offer useful guidance to the designer of HC devices, identifying key parameters that can be manipulated to achieve the desired level of cavitational activity at optimised hydrodynamic efficiencies. The models can be used to simulate detailed time-pressure histories for individual vapour cavities, including turbulent fluctuations. This in turn can be used to simulate cavity collapse and overall performance of HC device. The presented approach and results offer a useful means to compare and evaluate different cavitation device designs and operating parameters.

Sensitivity Analysis of Fuel Injection Characteristics of GDI Injector to Injector Nozzle Diameter

“…The analytical process follows mass conservation, kinetic energy conservation, and the continuity equation. On this basis, the κ − ε turbulence model, the Euler model, and the Rayleigh equation considering cavitation change are used [15].…”

Modelling of vortex based hydrodynamic cavitation reactors

“…Designs of cavitation reactor: Conventionally hydrodynamic cavitation reactors are designed either using small constrictions (like orifices or venturi) or rotors to realise the desired low pressure regions for generating cavitation. Orifice or venturi based designs are susceptible to clogging and erosion since cavitation occurs close to solid walls (see for example, Simpson and Ranade, 2018a). Reactors based on rotors are expensive and impose higher operating and maintenance costs (Gogate and Pandit, 2001).…”

“…It is therefore difficult to relate results of one study with the other since these devices lack standardisation. It should be noted that small hardware features like thickness of orifice plate and radius of curvature of orifice (see Simpson and Ranade, 2018a) can significantly influence cavitation characteristics. Many times, not all of the relevant dimensions and operating conditions (like cavitation inception conditions, volume of holding tank etc.)…”

Role of mineral flotation technology in improving bitumen extraction from mined Athabasca oil sands—II. Flotation hydrodynamics of water‐based oil sand extraction

“…The formulation and numerical solution of multiphase computational fluid dynamics (CFD) models have recently been used to evaluate geometric parameters of orifice devices used for hydrodynamic cavitation . Cavitation behaviours were drastically affected by the orifice thickness (ie, length of the hole).…”

“…For example, for the ratio of orifice thickness to diameter from 1‐5, the pressure ratio required to initiate cavitation changed by a factor of 10. The analysis revealed that all the geometric parameters (such as inlet radius, hole inlet sharpness, and wall angle) affect cavitation intensity …”