Control method of inlet turbulent intensity in rotating channel and validation

In the experiments of rotating channels, in order to acquire an ideal inlet turbulent intensity in rotating channel and better simulate the flow and heat transfer in a inner-cooling channel of turbine, a control method of inlet turbulent intensity was proposed and implemented by experiment in current work. In a square channel of 40mm×40mm, a hot wire anemometry is used to measure the turbulent characteristics downstream of a grid which has a diameter of 3mm and mesh size of 12mm. The grid Reynolds numbers range from 2200 to 3900. It is shown that the turbulent intensity of flow after the grid increases significantly and then decreases along downstream direction. Its value on the same position increases as the grid Reynolds number increases. In a short length, the flow after the grid reaches a turbulent intensity of 5% which is equal to the value in a real turbine inner-cooling channel. Besides, it is revealed that the flow will be more likely to become homogeneous and isotropic at a lower grid Reynolds number. A classic formula was used to fit the data of turbulent intensity in central channel after grid along downstream direction. The experiment data fit well with the curves.