Impingement Heat Transfer Enhancement on a Cylindrical, Leading Edge Model With Varying Jet Temperatures

Abstract

Stagnation region heat transfer coefficients are obtained from jet impingement onto a concave surface in this experimental investigation. A single row of round jets impinge on the cylindrical target surface to replicate leading edge cooling in a gas turbine airfoil. A modified, transient lumped capacitance experimental technique was developed (and validated) to obtain stagnation region Nusselt numbers with jet-to-target surface temperature differences ranging from 60 °F (33.3 °C) to 400 °F (222.2 °C). In addition to varying jet temperatures, the jet Reynolds number (5000–20,000), jet-to-jet spacing (s/d = 2–8), jet-to-target surface spacing (ℓ/d = 2–8), and impingement surface diameter-to-jet diameter (D/d = 3.6, 5.5) were independently varied. This parametric investigation has served to develop and validate a new experimental technique, which can be used for investigations involving large temperature differences between the surface and fluid. Furthermore, the study has broadened the range of existing correlations currently used to predict heat transfer coefficients for leading edge jet impingement.

Analysis of heat transfer and fluid flow of a slot jet impinging on a confined concave surface with various curvature and small jet to target spacing

“…2001;Gau and Chung,1991;Yang et al, 1999;Choi et al, 2000;Figure 16. Local Nusselt number, TKE/U in 2 , p, velocity magnitude, negative v velocity and w velocity distributions along L1 for Re j = 40000 at R 2 /B = 8 HFF 29,8 Cornaro et al,1999;Martin et al, 2012;Zhou et al, 2017). This can be related to the second peak of high turbulence disturbances at high Reynolds number conditions and lower blockage effect for larger surface curvature (R 2 /B).…”

“…Later, Martin et al (2012) experimentally explored the temperature effects on the heat transfer for an array of round jets impinging on a cylindrical leading edge model with varying jet Reynolds number (5000-20,000), jet-to-jet spacing (2-8), jet to target surface spacing (2-8), and impingement surface diameter-to-jet diameter (D/d = 3.6, 5.5). Furthermore, the study broadened the range of existing correlations for prediction of heat transfer coefficients for leading edge jet impingement.…”

State-of-the-Art Cooling Technology for a Turbine Rotor Blade

“…The impingement cooling makes use of the Chupp correlation [11,14]. The correlation includes the hole diameter (d), the distance of the jet exit plane to the apex of the target surface (l), the center-to-center spacing of the jets (s), and the diameter of the target surface (D) (see the below equation):…”

High Reynold Number LES of a Rotating Two-Pass Ribbed Duct

“…Internal cooling mandates that for a given coolant inlet temperature, the convective heat transfer coefficient is as high as possible without excessive pressure losses in the flow circuit. Thus different heat transfer coefficient enhancement techniques are used to turbulate the flow in the passages by placing features in the form of ribs [1,2], pins [3], dimples [4], and other more esoteric combinations [5,6] often combined with slot and jet impingement techniques [6][7][8][9][10][11], skin cooling, etc. In the past, and even to some extent in the present, internal cooling geometries have been limited by manufacturing constraints-however, with advances in additive manufacturing and 3D printing of metals and alloys, this constraint will eventually be eliminated to a large degree.…”