Computational analysis of flow conditions in hydrodynamic cavitation generator for water treatment processes

Abstract

The research on the potential of cavitation exploitation is currently an extremely interesting topic. To reduce the costs and time of the cavitation reactor optimization, nowadays, experimental optimization is supplemented and even replaced using computational fluid dynamics (CFD). One of the approaches towards sustainable water treatment is the use of the cavitation reactor with bluff elements mounted on its stator and rotor. The experimental results show that, besides the rotational speed, the spacing of the rotor pins has the most significant effect on the cavitation intensity and effectiveness, while the pin diameter and the surface roughness are less significant design parameters. The present paper uses a simplified CFD approach to investigate the conditions in the reactor and to select the optimal among a number of geometry variations.

Multiparametric experimental analysis of the pin disc rotational cavitation generator

“…The latter is attributed to multiple cloud bursts that occurred simultaneously behind several rotor pins, causing pressure perturbations that propagated throughout the housing chamber. This phenomenon was to some extent observed in the [20] and will be further experimentally investigated using a wider viewing angle to capture dynamics of entire chamber.…”

“…As shown in the numerical study of the pin disc RGHC [20], the result of cavitation is a complex pressure-velocity field, which is also evident in the dynamics of the acquired pressure signal. While some of the dynamic features can be attributed to the geometric features and the rotational frequency, there are others such as 547 Hz that can be linked to the dynamics of the cavitation cloud detachment and collapse.…”

“…Cavitation occurs in the low pressure wake behind the pin on the rotor and has been previously studied experimentally on a pilot scale [18,19] (Fig. 1 -G) and numerically [20]. The pilot scale experimental results indicated significant mechanical and chemical effects that strongly depended on the operational and geometrical RGHC characteristics.…”

Preface to the computational fluid dynamics for chemical and process engineering special issue section

“…In Maluta et al, [ 1 ] Guarato de Freitas Santos et al, [ 2 ] and Gostia et al’s [ 3 ] work, advanced aspects of modelling, simulation, and optimization (MSO) of multiphase flows at the apparatus scale are addressed. Aiming at a more reliable simulation‐based scale‐up of gas–liquid stirred tanks and having both the need for predictive capabilities and computational costs in mind, Maluta et al [ 1 ] validate a two‐fluid model approach and discuss its limits and strengths.…”

“…They suggest a consideration of the carrier flow only, since the adjoint theory would not apply to the Lagrangian formulation, which has been the workhorse in particle‐induced erosion simulations. In Gostia et al’s study, [ 3 ] a simplified mixture model is used to study the flow in a rotating generator with hydrodynamic cavitation and, on this basis, to select the optimal geometry among a number of geometry variations.…”