Deposition Characteristics of Particles with Different Diameters in an Impingement-Effusion Structure with a Double-Wall Blade

Abstract

Ingestion and deposition of fine particles on the surface of the coolant passage degrade the blade’s cooling performance. This paper proposes a deposition model to investigate the complex deposition characteristics of fine particles during repeated collision, adhesion, rebound, and removal events in the small space inside a typical impingement-effusion structure with a double-wall blade. The results show that the particles rarely collide with the wall and escape directly from the film hole outlet when the particle diameters are smaller than 0.5 μm. Most particles with diameters of 0.5 to 1.0 μm are deposited after the first collision around the stagnation point in an area 0.35 times the pin-fin diameter. Some particles with diameters of 1.0 to 3.0 μm are deposited in the stagnation region, but most are deposited between the two pin fins and near the film hole after the second collision. Particles with diameters larger than 3.0 μm are mainly deposited on the region enclosed by the adjacent pin fins and film holes after multiple collisions, and the escape rate of particles is higher than 30%. The escape rates of particles with diameters of 0.5 to 1.0 μm and 1.0 to 3.0 μm have the same trends, exhibiting a decrease followed by an increase with the increasing particle diameter. The particles entering the impingement-effusion structure, especially those with diameters of 0.7 -0.8 μm and 1.4 -2.4 μm, are primarily deposited on the target surface, resulting in the cooling performance degradation of double-walled blade.

Keywords

• impingement-effusion structure
• deposition model
• particle size
• deposition distribution
• degradation of cooling performance