Investigation of Velocity Ratio Difference between the Controlling Jets and the Main Jet in the Compound Triple Jets Arrangement to Modify the Film Cooling Effectiveness, Using the LES Approach

In this research، effects of blowing ratio (velocity ratio) difference between the controlling small jets and the main jet in the compound triple jets arrangement on the film cooling effectiveness and the flow hydrodynamics are investigated. This blowing ratio difference was selected such that the total mass flow rate of the cold flow becomes equal to that of the simple compound triple jets. The triple jets are inclined normally into the cross flow and the cooling jets to the hot cross flow temperature ratio and the jets Reynolds number are 0. 5 and 4700، respectively. The numerical approach is based on the finite volume and the SIMPLE algorithm over a multi-block، staggered، structured and non-uniform grid arrangement was applied. The numerical simulations are performed for three controlling jets to main jet velocity ratios. The obtained results show that when the velocity ratio is higher than unity، the film cooling effectiveness increases، while it decreases when the velocity ratio is less than unity. Due to high complication of the flow (results from interaction of three jets with the cross flow) and time dependency of the introduced vortex structures، the large eddy simulation approach was used to investigated the flow more accurately.