Asymmetric entrainment effect on the local surface temperature of a flat plate heated by an obliquely impinging two-dimensional jet

• Published in: International journal of heat and mass transfer Vol. 52; no. 21; pp. 5250 - 5257
• Main Authors: Vipat, O., Feng, S.S., Kim, T., Pradeep, A.M., Lu, T.J.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.10.2009; Elsevier
• Subjects: Applied sciences; Asymmetric entrainment; Cold jet; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fluid dynamics; Fundamental areas of phenomenology (including applications); Heat transfer; Heated jet; Inclination; Jets; Physics; Theoretical studies. Data and constants. Metering; Turbulent flows, convection, and heat transfer; Two-dimensional jet; Cold jet; Asymmetric entrainment; Two-dimensional jet; Inclination; Heated jet; Cooling; Oblique incidence; Interaction; Surface temperature; Two dimensional flow; Experimental study; Cold air; Heating process; Warm air; Asymmetry; Test facility; Entrainment; Jet; Heat transfer; Flat plate
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2009.04.007

The flow and temperature fields caused by a two-dimensional heating air jet obliquely impinging on a flat plate are experimentally characterized. Whilst the jet flow is discharged at Re Dh = 8.2 × 10 3 based on the hydraulic diameter of the orifice, D h , and the jet exit-to-plate spacing (separation distance) is fixed at 8 D h , the impingement angle (inclination) is systematically decreased from 90° (normal impinging) to 30° (oblique impinging). A separate experiment is carried out for a two-dimensional cooling jet obliquely impinging on a heated plate (constant heat flux). The results demonstrate that the response of local surface temperature to plate inclination behaves in a completely different manner. For impinging jet cooling, the inclination (from normal impinging position) reduces the local effective temperature values at corresponding points about actual stagnation point, inclusive of it. For impinging jet heating, the inclination causes, conversely, an increase in local surface temperature including the stagnation point temperature. However, the shifting of the actual stagnation point towards the uphill side of the plate is consistently observed for both hot and cold jet cases. This newly found feature for an obliquely impinging jet is attributed to the combined effects of asymmetric entrainment and momentum redistribution (i.e., thickening/thinning of hydraulic boundary layers on each side of the plate with respect to the actual stagnation point).