Numerical investigation on design parameters of orifice plate for positioning of workpiece in cavitation zone for cavitation machining

ABSTRACT

The recent development of non-traditional machining techniques, such as cavitation machining (CM), has been gaining traction amongst researchers due to its sustainable nature. The present research focuses on the use of computational fluid dynamics (CFD) model to predict the location of workpiece in the fluid domain and bubble distribution during CM process. For efficient CM, the correct positioning of a workpiece in cavitation zone is essential, as the implosion of the cavity bubble leads to formation of micro-jet and shock waves for a few milli-to-microseconds generating high temperature and pressure on workpiece. The aim is to harness cavitation phenomena in material processing, particularly by using orifice plates as a common tool to induce hydrodynamic cavitation. To generalise the investigation, the flow simulation through orifice plate with different aspect ratios (l/d) are carried out. For the bubble distribution and their diameters, the Lagrangian discrete phase model (DPM) is used in the downstream side of the flow domain. Using this information, bubble dynamics have also been investigated using the Keller–Miksis (KM) model to compute the implosion time and intensity in the zone. The presented exploration determines the orifice dimensions to optimize implosion intensity, ensuring precise workpiece placement in real-time CM.

KEYWORDS:

• Computational fluid dynamics
• cavitation machining
• hydrodynamic cavitation
• aspect ratio of orifice
• cavitation zone
• bubble distribution

Nomenclature

d	=	Diameter of orifice
l	=	Thickness of orifice
$\mathit{v}$	=	Velocity of fluid (m/s)
$\mathit{\rho }$	=	Density of phase (Kg/m3)
$\mathit{\mu }$	=	Dynamic viscosity (Pa.s)
$\mathit{k}$	=	Turbulent kinetic energy (m2/s2)
$\mathit{\sigma }$	=	Ratio of flow area $\left(\mathit{\sigma }=\frac{A_o}{A_p}\right)$, $A_o$= Area of orifice, $A_p$= Area of Pipe
${\sigma }_c$	=	Contraction coefficient
$\mathit{\epsilon }$	=	Turbulence dissipation rate (m2/s2)
$\mathit{\mu }$	=	Dynamic viscosity (Pa.s)
$\mathrm{\Gamma }$	=	Diffusivity (m2/s)
$\mathit{\alpha }$	=	Volume fraction of phases
$n_o$	=	Bubble number density
$\mathit{R}$	=	Radius (m)
$\mathit{P}$	=	Pressure (MPa)
$P_{\mathrm{\infty }}$	=	Ambient pressure (MPa)
X	=	X-coordinate
Y	=	Y-coordinate
Z	=	Z-coordinate
Subscript	=
$\mathit{B}$	=	Cavity Bubble
p	=	X-coordinate for part positioning
$\mathit{l}$	=	Liquid phase
$\mathit{v}$	=	Vapor phase
$\mathit{m}$	=	Mixture phase

Disclosure statement

No potential conflict of interest was reported by the author(s).