Integrity Evaluation of Micro-/Nanobubble Pump Impeller using Fluid-Structure Coupled Simulation

Abstract

Abstract-Micro-/nanobubble pump needs a high fluid pressure to generate the extra fine bubbles. The most effective method to increase the pressure is to increase the ratio of the number of vane impeller to pump volume. However, it can reduce the dimension of the vane which can degrade the integrity of the structural vanes due to loading. In this paper, the fluid-structure coupled simulation was used to evaluate the structural integrity of the impellerwith three loading conditions. The loads were acentrifugal force, hydraulic pressure, and the combination loads.The hydraulic pressure was imported from the flow calculation using gas-liquid two-phase flow simulation and the centrifugal force was applied to model due to a high rotational speed of the impeller.Based on the simulation results, the maximum stress due to the combination of centrifugal force and hydraulic pressure was8.205 MPaand it was secure with enough strength because it was less than the allowable design stress of 280 MPa. Furthermore, the maximum axial and radial deformation of the impeller were 0.0001 mm and 0.0027 mm respectively.However, they didn'taffect thenormal working of themicro-/nanobubble pump and the stiffness of impeller also met the requirements. The evaluation method and simulation results from this work can be used as a basic model for the further analysis and improvement of themicro-/nanobubble pump impeller.Keyword-micro-/nanobubble, computational fluid dynamics, fluid-structure interaction, centrifugal force, hydraulic pressure. and so on. Gas-liquid mixing pump is one type of microbubble generator that was designed based on hydrodynamic principles, which is very efficient for mixing gas and liquid directly and dissolve them. In general, this type of microbubble generator uses regenerative turbine pump. The regenerative pump is one type of turbomachine that has very simple and inexpensive construction. It achieves lower mass fluxes but higher-pressure differences than other pumps at the same circumferential velocity [10]. The conventional regenerative pump has a construction in which the fluid enters a set of radial impeller teeth which guides the fluid from the inlet to the outlet, both separated by a 300 0 annulus chamber producing a toroidal motion also known as regenerative flow [11]. For gas-liquid mixing pump application, a regenerative pump is designed to have two suction for gas and liquid which is mixed within the impeller at high pressures and high rotation to produce MBs and NBs.The most effective method to increase the pressure on theregenerative pump is to increase the ratio of the number of vane impeller to pump volume [12], however, it can reduce the dimension of the vane which can degrade the integrity of the structure due to loading. The fundamental force of the mixing pump is which driven by theelectrical motor is the fluid mechanical pressure loading on the impeller vanes. The thinner vanes can result in larger deflections due to the lower stiffness of the thinner structure. These deflections change the hydraul...