DSpace Collection:http://localhost:8080/xmlui/handle/123456789/27032026-06-23T06:33:32Z2026-06-23T06:33:32ZLocal heat transfer for jet impingement onto a concave surface including injection nozzle length to diameter and curvature ratio effectspatil, V. S.http://localhost:8080/xmlui/handle/123456789/27042020-02-06T05:59:17Z2017-08-04T00:00:00ZTitle: Local heat transfer for jet impingement onto a concave surface including injection nozzle length to diameter and curvature ratio effects
Authors: patil, V. S.
Abstract: The effect of jet nozzle length to diameter ratio on local heat transfer coefficient measurements for a row of
circular jets impinging onto a concave surface for varying target spacing are reported here. The nozzle length to
diameter ratio (L/d) and the nozzle to target spacing (H/d) were varied from 0.2 to 6 and 0.67 to 8 respectively.
Three curvature ratios, defined as the ratio of jet diameter to target surface diameter (d/D), equal to 0.1, 0.2 and
0.3 were studied and the jet to jet pitch to diameter ratio (P/d) was kept constant at 4.0. The Reynolds number
was varied between 10,000 and 50,000 and wall static pressures for some cases were measured for obtaining a
better understanding of the heat transfer coefficient variations.
Higher stagnation zone Nusselt numbers were observed for the jet nozzles with small L/d at small H/d values
whereas at larger H/d values nozzle length was observed to affect the data only marginally. The difference
between Nusselt number values, between H/d = 2 and H/d =8, was observed to progressively reduce with
increasing L/d ratio and this was true for both the local stagnation point as well as the spanwise averaged
stagnation line values. The maximum local Nusselt number values were observed to shift from the geometric
impingement location to nearby locations for very small nozzle diameter to target distance ratios (H/d≤ 1) for
larger curvature ratios. A constant heat transfer impingement area with constant pumping power criterion is
presented to compare the performance of the different configurations studied. The longer nozzle lengths and
smaller curvature ratios are observed to perform better based on this criterion. A correlation is presented for the
overall averaged Nusselt number, with a validity within the parameter range studied, with a±10% error band2017-08-04T00:00:00Z