FLOW VISUALIZATION OF RECTANGULAR SLOT AIR JET IMPINGEMENT ON FLAT SURFACES

Jet impingement near the mid-chord of the gas turbine blade is treated as a flat plate. Experimental and numerical investigations are carried out for a single slot air jet impinging on flat surface for two different rectangular slots of dimension (3mm x 65 mm) and (5mm x 65 mm). Experimentation is done to study the flow pattern topography on the flat target plate, with varying the flow rate from 20 LPM to 50 LPM by varying the nozzle to plate distance from 9 mm to 24 mm for slot jet of 3mm and varying the nozzle to plate distance from 10 mm to 30 mm for slot jet of 5mm. Lampblack flow visualization technique has been used for visualizing the flow pattern of impinging jets on the flat plate. The computational results have been compared with experimental by solving the set of governing equation have been solved for flowing fluid over the geometry. The Navier-Stokes equations are solved for steady flow turbulent cases. The flat plate problem has been modeled and meshed in Ansys 14.5 workbench and solved in Fluent. The numerical analysis is validated with experimental work, and it is found that the computational results are agreeing with experimental results with an error less than 15% indicating that the CFD analysis can be used reliably for visualizing the flow pattern for different configurations of single slot jet impingement. From current research study it is revealed that maximum shear zone width is influences in selection of neighboring jets besides the primary jet. For case considered for study the neighboring jets should be selected 15 mm away from the stagnation zone there by secondary heat transfer peaks can be achieved so that it enhances heat transfer in multi jet impingement cooling. This study gives clear idea how to choose multi slot jets side by side at correct distance from central stagnation zone. It also helps in avoiding abrasion of the surface particulates for mass transfer applications. Selection of efficient configuration of multi slot impingement arrangements offers efficient use of the fluid and for maintaining necessary cooling rate.