Jet impingement is most effective and active method for cooling and heating of any surface or system. The ability of jet impingement is greatly influenced by nozzle configuration and other dimensional and non-dimensional parameters. Impinging coaxial swirl jet generates interesting flow filed on any test surface and influences both pressure and heat distribution on impinging surfaces. In present study, an experimental investigation is carried to analyze the effects of turbulent coaxial swirl jet on the pressure distribution (PC & PCO) on convex element. For better and acceptable results, the desirable parameters are identified from previous research works. The present experimental result highlights the independency of pressure coefficient (PC) for jet-Reynolds number (Re=70000 to 45000), effect of circumferential angle (θ) or inclination of test element, effect of jet exit to test element distance (Z/dh) and effect of confinement on PC & PCO pattern on a convex test element. The higher pressure coefficient value are obtained at lower Z/dh = 1 & at θ = 15° to 12°and significant drop in the values are seen with increase in the Z/dh & θ. At θ = 20° to 30° the value of PC & PCO reaches to negative magnitude. The use of confinement tube enhancementthe pressure distribution (PC & PCO) by 61% to 64% is seen for the same flow conditions.
The experimental investigation is carried out to study the distribution of wall static pressure (Cp & Cpo) on the convex smooth surface by air jet impingement. A great deal of attention was paid to analyze the effects of orifice geometry for various flow and geometric conditions, a comparison of the wall static pressure coefficient is done for different orifice. The experimental results show that the wall static pressure on a convex test section is higher for rectangular orifice compared to other orifice. The wall static pressure decreases circumferentially from its maximum value at the stagnation point (θ = 0°) and also for higher Z/dh. Higher value of Cp and Cpo are obtained for unconfined flow. The experiments were performed with the following parameters: the jet Reynolds number (Re) = 10000–50000, the orifice-to- convex surface distance (Z/dh) = 1–5, Circumferential angle (θ) = 0° to 30°, Curvature ratio (D/dh), Orifice = Circular, Square, Triangle, Rectangle.
The distribution of wall static and stagnation (CP and CPO) pressure coefficient on a flat rectangular element by impinging air jet from the hexagonal orifice is obtained from experimentation. The past research studies helped to identify key parameters such as orifice geometry, jet exit-to-plate-distance (Z/dj), test section inclination (θ), jet Reynold number (Re), lateral distance-to-jet diameter (X/dj), test surface type and geometry, for better and acceptable results. The experimental outcome helps to know the effect of identified key parameters on wall static and stagnation pressure on a rectangular test plate in a confined flow path. The independent nature of wall static pressure is observed for all jet Reynold number (10000 ≤ Re ≤ 50000). Higher pressure coefficient values were observed at lower Z/dj = 1, X/dj = 0 and θ = 0. A significant drop in CP values are seen with the increase in Z/dj, X/dj and θ. The experimental CP and CPO contribution of confined flow are compared against the unconfined flow, around 48% to 58% enhancement is observed when confinement is used. Experimental pressure drop measurements across orifice were made and pressure loss coefficient (PC) for hexagonal orifice of confined and unconfined condition are reported.
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