Experimental and computational study of heat transfer and flow structure of slotted impinging jet

Abstract

The study is focused on the flow parameters of the slotted impinging jet associated with its heat transfer performance. The analysis is performed for the circular and slotted jets of square, cross, and oval sections for flow outlet to target plate distance of L/D = 1 to 4. The Reynolds number range of 12700 – 23000 is used in this study to analyze the heat transfer pattern using liquid crystal sheet. The numerical analysis is carried out using CFD. The axial velocity peak (u/U0 = 2.124) is observed for the square jet corresponding to r/D = 0.33 at L/D = 1 and the peak reduces with increasing L/D distances. Higher intensity of average radial velocity (ur/U0 = 1.44) is observed close to the impinging plate for the slotted jet at L/D = 1 at 0.5 ≤ r/D ≤ 1.4 compared with radial velocity (ur/U0 = 0.91) of circular jet. Nusselt number distribution has little dependence for circular jet on the separation distance as the variation is marginal at L/D = 4 when compared to L/D = 1 and 2, the slotted jet however shows marked variation of Nusselt number (136.8 at L/D = 1, 135.2 at L/D = 2 and 113.5 at L/D = 4) in the region at X/D = 1.5. The highest values of turbulence intensity (TI = 0.206) is observed at r/D = 0.5 for the square jet at L/D = 3.

Keywords

• Flow Structure
• Heat Transfer Enhancement
• Numerical Simulation
• Slotted Jet
• Thermochromic Liquid Crystal

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