Effect of the injection angle on local heat transfer in a showerhead cooling with array impingement jets

An experimental study was conducted to investigate the effect of the injection angle for staggered array impingement jets in a showerhead cooling system. We suggested the angled jets array to enhance heat transfer performance, and heat transfer characteristics were compared to that on the normal jets array. The semicircle test section was designed to consider the showerhead configuration, and the Reynolds number was changed from 3000 to 10,000. The naphthalene sublimation method was used to evaluate the heat transfer coefficients on targeted plates, and the numerical simulations were carried out to analyze the characteristics of the flow fields. The averaged heat transfer coefficient increased monotonically with increasing Re-d due to the enhanced flow mixing by increasing mass flow rate. A low heat transfer coefficient was observed among the adjacent impingement jets in the vicinity of the central row of holes due to staggered array pattern and curvature effect. To overcome this disadvantage, the inclined jets were applied in present study. The heat/mass transfer coefficients were larger for the inclined jets for all Re-d because an amount of wall jet is flowed toward the low heat transfer region by flow imbalance. As applied inclined array impingement jets, averaged heat transfer was enhanced about 9% in low Re-d compared to normal array impingement jets.