The impingement of circular, liquid jets provide a convenient method of cooling surface. The method of transfer by impinging jet has wide applications such as cooling of aircraft parts, steel manufacturing process, grocery dryness, clothing dryness and in film and paper manufacturing process.
Focus of previous researches was heat transfer phenomenon when liquid jets impinge a upward facing plate. But, it did not present about heat transfer phenomenon when liquid jets impinge to the downward facing plate against the gravity.
Hence, Present study investigates a heat transfer phenomenon when a single round jet impinges a downward facing circular plate against the direction of gravity.
Experimental investigation is performed for jet flow rate 3.6L/min, 4.6L/min and 5.6L/min, jet fluid temperature of 24℃, isothermal condition 60℃, 70℃ and 80℃, H/D=1, 3 and 8 with a single round jet diameter 4mm, 6mm, and 8mm.
Results as;
When isothermal condition is increased at same conditions(nozzle flow rat, nozzle diameter, H/D), the local heat transfer coefficient() of heated circular plate is same.
In case of D=4mm and 6mm, change of by increase of H/D is little. But incase of D=8mm, effect of heat transfer decrease because of the strong influence of potential core length in low discharge velocity.
In same condition(isothermal condition, nozzle diameter, H/D), the larger nozzle flow rate, the more increasing the effect of heat transfer. And the tendency is same. And in same nozzle flow rate condition, the smaller nozzle diameter, the highest .
In stagnation region of all , is the highest. After, decrease rapidly, and decrease slowly due to the formation of wall jet.
As a results of experiment is obtained correlation equation, , for 70℃, H/D=1,3,8, G=3.6L/min, 4.6L/min ,5.6L/min, between D=4mm and 8mm.