High-speed droplet impact is of great interest to power generation and aerospace industries due to the accrued cost of maintenance in steam and gas turbines. The repetitive impacts of liquid droplets onto rotor blades, at high relative velocities, result in blade erosion, which is known as liquid impingement erosion (LIE). Experimental and analytical studies in this field are limited due to the complexity of the droplet impact at such conditions. Hence, numerical analysis is a very powerful and affordable tool to investigate the LIE phenomenon. In this regard, it is crucial to understand the hydrodynamics of the impact in order to identify the consequent solid response before addressing the LIE problem. The numerical study of the droplet impingement provides the transient pressure history generated in the liquid. Determining the transient behavior of the substrate, in response to the pressure force exerted due to the droplet impact, would facilitate engineering new types of surface coatings that are more resistant to LIE. To that end, quantifying the impact pressure of compressible liquid droplets impinged at very high velocities, up to 500 m/s, on rigid solid substrates and liquid films is the main objective of the present work. A wide range of scenarios that commonly arise in the LIE problem are considered, i.e., droplet sizes between 200 µm and 1000 μm, impact velocities ranging from 100 m/s to 500 m/s, and liquid film thicknesses of 0 µm–200 μm. The maximum pressure exerted on the solid surface due to the droplet impact is calculated for both dry and wetted substrates. The results obtained from compressible fluid modeling are compared to those of other numerical studies and analytical correlations, available in the open literature. New correlations are developed for maximum impact pressure on rigid solids and liquid films that can be used to characterize the solid stress and estimate the lifetime of the material by carrying out the fatigue analysis.

High-speed droplet impact is of great interest to power generation and aerospace industries due to the accrued cost of maintenance in steam and gas turbines. The repetitive impacts of liquid droplets onto rotor blades, at high relative velocities, result in the blade erosion, which is known as Liquid Impingement Erosion (LIE). Experimental and analytical studies in this field are limited due to the complexity of the droplet impact at such conditions. Hence, numerical analysis is a very powerful and affordable tool to investigate LIE phenomenon. In this regard, it is crucial to understand the hydrodynamics of the impact in order to identify the consequent solid response before addressing the LIE problem. The numerical study of the droplet impingement allows to obtain the transient pressure history generated in the liquid. Knowing the transient behavior of the substrate, in response to pressure force exerted due to the impact, would facilitate engineering new types of surface coatings that are more resistant to LIE. To that end, modeling the impact of compressible liquid droplets at high velocities on rigid solid substrates is the main objective of the present work. The results obtained from the compressible fluid modeling are validated against the numerical studies and analytical correlations, available in open literature.

Droplet impingement is of great interest to power generation and aerospace industries due to the accrued cost of maintenance in steam and gas turbines. The repetitive impacts of liquid droplets onto rotor blades, at high relative velocities, result in the blade erosion, which is known as Liquid Impingement Erosion (LIE). In this regard, it is crucial to understand the hydrodynamics of the impact in order to identify the consequent solid response before addressing the LIE problem. To that end, modeling the impact of liquid droplets onto the blade surface is the main objective of the present work. A novel model for Fluid-Solid Interaction is developed that couples the gas-liquid interfacial model with the structural solver using one-way and two-way coupling algorithms. Furthermore, the effect of the solid elasticity on the generated pressure build-up in the liquid and the resulting stress in the solid are investigated.

The impact of a liquid droplet onto an elastic substrate is modeled in the current work. Volume of Fluid Method is used to model the interfacial flow in the fluid region which contains both liquid and gas phases. The droplet deformation is precisely captured upon impact at impingement velocities as high as 200 m/s. In this regard, incompressible Volume of Fluid solver is used for low impact velocities and a compressible model is implemented at high impingement velocities. In addition, the solid substrate is modeled with Finite Element Method. A novel Fluid-Solid Interaction model is developed that couples the gas-liquid interfacial model with the structural solver utilizing the two-way coupling approach. The coupling between fluid and solid is achieved by using the stress continuity on the fluid-solid interface and no-slip velocity condition. The pressure field in the fluid domain and the stress field in the solid domain are obtained simultaneously by solving coupled fluid and solid equations. The effect of the fluid compressibility on the generated pressure build-up in the liquid and the resulting stress in the solid is investigated. The results obtained from the Fluid-Solid Interaction model are validated for an impingement velocity of 100 m/s. Nomenclature D = droplet diameter E = Young's modulus F = deformation gradient tensor g = gravity n = normal direction p = pressure S = St. Venant-Kirchhoff tensor t = time th = thickness U = displacement V = velocity Greek letters: α = volume fraction σ = stress tensor δ = deflection µ = viscosity, Lamé coefficient λ = Lamé coefficient ν = Poisson ratio ρ = density ψ = isothermal compressibility factor Subscripts: 0 = initial condition f = fluid l = liquid s = solid