Experimental study on flow characteristics of rectangular narrow channel

Plate fuel elements is gradually used in advanced reactor structure design because of its advantages of high fuel consumption and high safety. The flow channel of the plate fuel element is a typical rectangular narrow channel, and accurately obtaining the flow characteristics of the rectangular narrow channel has become the most basic problem in the thermal and hydraulic research of the rectangular narrow channel. The flow characteristics of a rectangular narrow channel with cross-section of 3 × 67 mm and length of 745 mm are studied experimentally. The mass flow range is 50–650 kg/h, the pressure is 0.1–1 MPa, and the range of the inlet temperature is 283.15–333.15 K. The Reynolds number obtained experimentally in the laminar-turbulent transition region is in the range of 2700–4000, which has a significant delay compared to round channels. Laminar flow is modeled theoretically, and the Fourier sine transform method is used to solve the momentum Navier-Stocks equation, and the expression of the friction coefficient is obtained through the velocity distribution. However, due to the particularity of the test section, the error of the theoretical solution is large compared with experimental data. Five empirical correlations commonly used in rectangular narrow channels are evaluated. The Leon correlation is applicable to the experimental laminar flow area, and the Blasius correlation is applicable to the turbulent flow area. In order to further reduce the error, the friction correlation applicable to this experimental condition is fitted, making the prediction of friction coefficient more accurate. For subsequent experimental research on heat transfer, flow pattern, CHF, flow instability, etc., these works are of great significance. © 2020 Xi'an Jiaotong University