Numerical and experimental investigation of shedding mechanisms from leading-edge cavitation

https://research.chalmers.se/publication/509907/file/509907_Fulltext.pdf

A comparative study between numerical methods in simulation of cavitating bubbles

A numerical study on the effect of cavitation erosion in a diesel injector

Euler–Lagrange study of cavitating turbulent flow around a hydrofoil

A multi-scale Euler–Lagrange method was developed and applied to numerically assess cavitation-induced erosion based on the collapse dynamics of Lagrangian bubbles. This approach linked macroscopic and microscopic scales and captured large vapour volumes on an Eulerian frame, while small vapour volumes were treated as spherical Lagrangian bubbles. Interactions between vapour bubbles and the liquid phase were considered via a two-way coupling scheme. A verification and sensitivity study of the developed procedure to transform vapour volumes between Eulerian and Lagrangian frames was performed. First, the developed method was validated for bubble dynamics, using analytical and experimental data. Second, the cavitating flow through an axisymmetric nozzle was simulated using a measurement-based distribution of cavitation nuclei. Details of single bubble collapses were used to assess cavitation erosion. Based on well-recognised fundamental experiments and theoretical considerations from the literature, model assumptions were derived to account for the effects of a bubble’s stand-off distance on the bubble’s motion and its radiated pressure during an asymmetric near-wall bubble collapse. Computed maximum collapse radii of bubbles correlated well with diameters of measured erosion pits. Considering a nonlinear dependence of erosion on impact pressure, calculated erosion potentials compared well to measured erosion depths.

/pdf/numerical-assessment-of-cavitation-induced-erosion-using-a-3r4u1fty4h.pdf

Numerical assessment of cavitation-induced erosion using a multi-scale Euler–Lagrange method

https://research.chalmers.se/publication/521981/file/521981_Fulltext.pdf

Numerical assessment of cavitation erosion risk using incompressible simulation of cavitating flows

https://research.chalmers.se/publication/506312/file/506312_Fulltext.pdf

Realizability improvements to a hybrid mixture-bubble model for simulation of cavitating flows

Transient cavities generated from unsteady leading-edge cavitation may undergo aggressive collapses which are responsible for cavitation erosion. In this paper, we studied the hydrodynamic mechanisms of these events in the leading edge cavitation formed over a modified NACA0009 hydrofoil using experimental and numerical methods. In the experimental investigation, high-speed visualization (HSV) and paint test are employed to study the behavior of the cavitating flow at σ = 1.25, β = 5°, U∞ = 20 m/s. In the numerical part, the same cavitating flow is simulated using an inviscid density-based compressible solver with a barotropic cavitation model. The numerical results are first compared with the experimental HSV to show that the simulation is able to reproduce the main features of the cavitating flow. Then, as the compressible solver is capable of capturing the shock wave upon the collapse of cavities, the location of collapse events with high erosion potential are determined. The location of these collapse events are compared with the paint test results with a qualitatively good agreement. It is clearly observed, in both the experiments and the numerical simulation, that there exists four distinct regions along the hydrofoil with higher risks of erosion: (1) A very narrow strip at the leading edge, (2) an area of accumulated collapses at around 60 percent of the sheet cavity maximum length, (3) an area around the closure line of the sheet cavity with the highest erosion damage, and (4) a wide area close to the trailing edge with dispersed collapse events. A combined analysis of the experimental and numerical results reveals that the small-scale structures generated by secondary shedding are more aggressive than the large-scale cloud cavities (primary shedding). It is also observed that the high risk of cavitation erosion in regions 2 and 3 is mainly due to the collapses of the small cavity structures that are formed around the sheet cavity closure line or the rolling cloud cavity.

Mohammad Hossein Arabnejad

Papers

Numerical and experimental investigation of shedding mechanisms from leading-edge cavitation

A comparative study between numerical methods in simulation of cavitating bubbles

Numerical assessment of cavitation erosion risk using incompressible simulation of cavitating flows

Realizability improvements to a hybrid mixture-bubble model for simulation of cavitating flows

Hydrodynamic mechanisms of aggressive collapse events in leading edge cavitation