Investigation on flow turbulent characteristics of plate-fin and tube-fin heat exchanger

In the continuous wind tunnel, the heat exchanger is installed upstream the test section to balance the heat which is generated by the fan or the compressor to control the total temperature in the test section. The heat exchange efficiency and the total pressure loose ratio are two important performance parameters of the heat exchanger in the wind tunnel. On the other hand, the flow dynamic characteristics such as the turbulence intensity and the noise of the heat exchanger can influence the flow dynamic quality of the wind tunnel significantly. In the 0.55 m×0.40 m low noise aeronautics acoustic wind tunnel, the hot wire is used to measure the velocity and the turbulence intensity distribution downstream the tube-fin heat exchanger and the plate-fin heat exchanger, and the total pressure loose ratio is also gained. The CFD method is used to simulate the flow structure and the self-turbulent intensity of these two types of heat exchangers. The study results show that the flow straightening characteristics of the tube-fin heat exchanger and the plate-fin heat exchanger have significant differences. The turbulent intensity and velocity uniformity downstream the tube-fin heat exchanger are better than that downstream the plate-fin heat exchanger, while the plate-fin heat exchanger has better straightening performance on horizontal turbulence. The self-turbulent intensity of the plate-fin heat exchanger is lower than the tube-fin heat exchanger. The investigation has important engineering application value for design of large scale continuous wind tunnels which have advanced flow quality requirements.