Effect of suction hole on heat transfer characteristic of internal passage

Experimental investigations of heat transfer characteristics near the entrance of a suction hole were carried out with proportionally enlarged model. The distributions of local heat transfer coefficients were measured with the heat-film method. Tests were performed with Reynolds numbers (based on average velocity of mainstream and hydraulic diameter of the internal passage) changing from 2.5 × 10⁴ to 1 × 10⁵ and suction ratios (SR) changing from 1.0 to 4.0. Influences of Reynolds number and suction ratio on heat transfer characteristic are studied. Results indicate that heat transfer coefficients are enhanced obviously in the downstream area of the suction hole by the suction effect. The increasing of suction ratio leads to higher heat transfer enhancement in this area; while the changing of Reynolds number contributes no remarkable effect on increasing the value of Nu/Nu₀, which representing the heat transfer enhancement extent.