Modeling of Liquid Droplet Impingement onto Ti-6Al-4V Substrate

Abstract

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.

Liquid–Solid Impact Mechanism, Liquid Impingement Erosion, and Erosion-Resistant Surface Engineering: A Review

“…One-and two-dimensional models can only represent liquid columns and cylinders, respectively, and not a spherical droplet. Hence, a two-dimensional, axisymmetric, two-way coupled FSI framework for rigid and elastic Ti-6Al-4V surfaces was developed in [200][201][202]. It was shown that the impact of fluid compressibility on the accumulation of pressure and the resulting solid stress cannot be disregarded for impingement speeds exceeding 100 m/s.…”

“…It is noteworthy that WDE for most solids occurs at impingement speeds above 100 m/s (see Table 1). Since the solid deformation, even under high impact velocities, is negligible for metals [202], it is possible to decouple the fluid and solid domains in order to reduce the computational cost in the simulations. To that end, a 2D axisymmetric geometry for spherical droplets with a compressible VOF model [170,171] (in which the ideal gas assumption for the air and Tait's equation of state (EOS) for water were used [203]) was employed parametrically for a wide range of impingement scenarios on both dry and wetted substrates [172] to obtain a correlation for the maximum impact pressure.…”

Flow Characterization of a Water Drop Impinged onto a Rigid Surface at a High Speed and Normal Angle in the Presence of Stagnant Air at Ambient Condition

“…They have illustrated that the substrate oscillation due to solid elasticity can cause splashing. A two-dimensional, axisymmetric, two-way coupled Fluid-Solid Interaction model for impingement of liquid droplets onto rigid and elastic Ti-6Al-4V substrate was presented by Marzbali [16], Marzbali et al [17] and Marzbali & Dolatabadi [18]. It was illustrated that the fluid compressibility effect on the pressure build-up and solid stress cannot be neglected for impingement velocities above 100 m/s since the increase in liquid density would be more than 5%.…”

2D Axisymmetric Modelling of Single Liquid Droplet Impingement at High Speeds on Thin Liquid Films in Compressible Regime

“…Blake and De Conick [8] have extended the molecular-kinetic theory of dynamic wetting by considering the effect of fluid-solid interaction. A 2-D axisymmetric, two-way coupled Fluid-Solid Interaction model for impingement of liquid droplets onto rigid and elastic Ti-6Al-4V substrate was presented by Marzbali [9], Marzbali et al [10] and Marzbali & Dolatabadi [11]. It was illustrated that the fluid compressibility effect on the pressure build-up and solid stress cannot be neglected for impingement velocities of 100 m/s and above.…”