网格式肋化通道换热与总压损失特性研究

通过两个实验模型,对矩形网格式肋化通道的换热与总压损失特性进行了实验研究。模型通道的两个宽边是由铝板机械加工而成的肋化壁,两个短边是由胶木板制成的绝热壁。肋化壁上肋与通道轴线所形成的锐角定义为肋向角α,第一个模型的两个宽边上的肋向角分别为45°和-45°(简称45/45模型);第二个模型两宽边的肋向角分别为45°和-60°(简称45/60模型)。两个模型的肋宽与肋间距之比t/p=0.25,肋间距与肋高之比t/e=0.30,肋高与通道高度之比e/H=0.50,即两个肋化壁的肋尖相互接触,从而形成网格式通道。实验表明当雷诺数在0.5×105～1.2×105范围内变化时,网格式内冷通道换热效果比光滑通道提高了5～9倍,但伴随的总压损失增加了3个数量级。 

Experimental Study of Heat Transfer and Total Pressure Drop of a Grid-Ribbed Rectangular Channel

The characteristics of heat transfer and total pressure drop of flow in an internally ribbed rectangular channel were studied experimentally by using two experimental models.The two larger sides of the models were made of ribbed aluminum plates;the two smaller sides were made of bakelite plates and treated as adiabatic surfaces.The acute angle between the ribs and the axis of the channel was defined as the rib angle.For the first experiment model,the rib angles for the two ribbed wall were 45° and -45° respectively,which was known as 45/45 model ,and for the second experiment model,the rib angles were 45° and -60° respectively,named as 45/60 model.All ribbed plates had rib width to pitch ratios t/p of 0.25, rib width to height ratios t/eof 0.3,and rib height to channel height ratios e/H of 0.5.The ribs from each plate of the channel were in contact with each other in their tips,and oriented so as to form a grid pattern.The experimental Reynolds number was in the range of 0.5×105～1.2×105.The experimental results showed that,in comparison to fully developed flow in a smooth pipe of equivalent hydraulic diameter the Nusselt number inside the grid-ribbed rectangular channel was increased up to 5 to 9 times higher,and total pressure drop was enlarged by up to three orders of magnitude.