Session: 15-01 Jet Impingement

Paper Number: 82152

82152 - Flow Visualization Study From a Flat Plate With Multiple Impinging Jets for Different Cross-Flow Schemes 

The modern-day aero-engine gas turbines are operated at temperatures beyond the normal melting point of the material to yield high efficiency and specific work output. Different internal and external cooling techniques are employed to keep the material within the safe limit, among which jet impingement cooling is one of the most effective internal cooling techniques. Multiple impinging jets are used to cover the large span of the cooling area and its overall heat transfer can be further enhanced by inducing directional heat transfer through different crossflow techniques.

The present work is aimed at studying the flow topology on the impingement surface computationally using skin friction lines, to reveal the details of the flow phenomena. Simulations were carried out on a flat plate with a 5×5 matrix of impinging jets, for three types of crossflow schemes (viz. minimum, medium, and maximum), four jet-to-plate spacings (H/D = 1, 2, 3 & 5), and three turbulent jet Reynolds numbers (15000, 25000, and 35000). The computations are carried out by using commercial code finite volume solver ANSYS FLUENT. The k-omega SST model is used for turbulence closure in simulations after validation practice with published literature data.

The three-dimensional flow separations (namely: counter-rotating vortex, wall eddies, up-wash fountain) and the heat transfer distribution are explained with the help of nodal points of attachment and separation, saddle points, and lines of attachment and separation.

The skin friction lines on the interaction surface change their pattern with jet-to-plate spacings and crossflow. At lower jet-to-plate spacing, the effect of crossflow on the flow structure and heat transfer rate is more prominent. The localized heat transfer rates are higher at low jet-to-plate spacing, but the uniformity in temperature distribution is obtained with higher jet-to-plate spacings. For the maximum crossflow condition, the heat transfer coefficient continuously increases at the interaction point towards the exit of the plate for lower jet spacings. At medium and maximum crossflow cases the heat transfer pattern changes with distance from the center of the plate. The effects of crossflow remain marginal for the highest jet-to-plate spacing. The flow structure on the surface is found to be independent of the Reynolds number under the investigated range.

Presenting Author: Radheesh Dhanasegaran LUT University

Presenting Author Biography: Radheesh Dhanasegaran is currently working as a Junior Researcher (Doctoral Student) in the Energy Technology department at LUT University, Lappeenranta, Finland. His doctoral thesis is focused on the Digital Twin Model of Marine Waste Heat Recovery Systems. His areas of interest include Experimental & Computational Heat Transfer, Turbomachinery, Modeling & Simulation of Dynamic Systems, and CFD.

Authors:

Radheesh Dhanasegaran LUT University
Ssheshan Pugazhendhi Indian Institute of Technology Madras