PROJECTS
Predicting Coefficient of Restitution for Particle Wall Collisions in Gas Turbine Components
To investigate the particle transport and its effect on different engine components, it is of prime importance to first understand the underlying physics of particle-wall interaction and quantify the energy losses in a particle-wall collision. Modeling the process of particle-surface impact is intricate, primarily because it is dynamic and nonlinear. A plethora of physical forces are involved during particle-wall collision, including elastic-plastic stress, electrostatic forces, thermophoresis, capillary forces and Van der Waals adhesion forces. For a dry collision, plastic deformation and adhesion losses are major contributors to energy losses; contribution of either mechanism depends on impact parameters: particles size, impact velocity and material properties of surfaces in contact.
The current model builds on existing models on elastic, elastic-plastic deformations and adhesion theories of particle–wall interaction. Collision is divided in to four stages and each stage is investigated separately.
1. Elastic compression stage
2. Elasto plastic compression stage
3. Restitution stage
4. Adhesion stage
The model is applicable to spherical particles undergoing oblique impact with a rigid wall. The model’s utility and accuracy were demonstrated by comparing with various experimental and FEM data for a range of particle size and contact materials. The predicted coefficient of restitution is found to be in reasonable agreement with experiments. The proposed model can be conveniently implemented with any computational fluid dynamics (CFD) code to predict sand particle transport in gas turbine components.
Many other physical forces are involved during particle-wall interaction, including electrostatic forces, thermophoresis, capillary forces and surface roughness effects. This current model does not include the effect for these mechanisms. Contribution of all these forces can be significant depending upon the impact conditions being investigated. Also, the current model does not include the temperature dependence of coefficient of restitution, which is important to study any gas turbine particle laden flows. The study of these effects is left for ongoing and future studies.
All the details are not presented on the website due to copyright and proprietary issues.
