Design And Characteristic Research Of The Water Drop-shaped Pins

The pin fin arrays are widely applied in heat transfer enhancement of internal cooling techniques for the turbine blades. The heat transfer level is raised with the pin fin arrays and the pressure loss is induced moreover. The researchers of pin fins in the past paid their attention to the geometrical shape and arrangement of the pin fins to obtain the higher overall cooling effectiveness with the lower possible penalty on the thermodynamic cycle performance. But their works were mostly based on the non-streamline pin fins with simple shape. A new type of streamline pin fin is designed in this paper –water drop-shaped pin fin. Both experimental and numerical method are used to analyze the heat transfer and pressure loss in rectangular channel with staggered arrays of circle-shaped, elliptic-shaped, and three kinds of water drop-shaped pin fins. The results show that the average Nusselt number of the endwall with water drop-shaped pin fin arrays have 23.9% lower than that of the circle-shaped pin fin arrays, while the pressure loss coefficients of the channel with the former three have 48.9%, 56.0% and 60.9% lower than that of the circle pin fin arrays respectively. Numerical computation is carried out further to study the effects of the attack angle and height of the pins and the structure of channel on the characteristics of the water drop-shaped pin fin arrays. Within the range of Reynolds number from 10000 to 40000,the heat transfer ability of the arrays increased sharply with the increasing Reynolds number while the pressure loss coefficients kept a degressive trend. The more attack angle, the more Nusselt number and the pressure loss coefficients. But the pressure loss increased fastly than the heat transfer enhancement. The height of the fins have little effect on the pressure loss coefficients. The 10 mm pins in height have the best heat transfer among arrays of the three heights. It is given that the average Nusselt number of the contractive channel is 1.3 times as much as that of the rectangular channel while pressure loss levels for the former is about 3-4.5 times higher than that of the latter. A great amount of dates are obtained on the heat transfer and pressure loss characteristics of water drop-shaped pin fin arrays. Abundant theoretical reference is supported for the choice of the effective cooling schemes of the turbine blades in modern aeroengines.