Influence of confinement on pressure and heat transfer distribution by impinging an air jet from a piccolo tube on a concave surface

Abstract

Experimental work is carried out to understand the effect of longitudinal confinement on wall static pressure and heat transfer distribution on a concave surface by impingement of an air jet from a piccolo tube (orifice). The experiments are conducted for different parameters such as orifice diameter (d = 10–16 mm), curvature ratio (D/d = 2–5), circumferential angle (θ = 0°−40°), orifice to target surface distance (Z/d = 1–4), confinement distance to the orifice diameter ratio (l/d = 15–9.375) and the Reynolds number of flow (Re = 5000–50,000). It is observed that the maximum wall static pressure and the Nusselt number occur at a stagnation point (X/d = 0 and θ = 0°) for all Z/d and l/d ratios. For confined flow, the value of wall static pressure (C_p and C_po) and the Nusselt number (Nu and Nu_o) distribution are higher when compared to unconfined flow conditions. The results of the study can be used in optimising the cooling system design.

KEYWORDS:

• Jet impingement
• static pressure
• curvature ratio
• confined flow
• piccolo tube
• Nusselt number

Disclosure statement

No potential conflict of interest was reported by the author(s).