The effect of tesla valves on turbine blade tip leakage

This paper introduces a novel blade tip design that incorporates the unidirectional flow control technology of Tesla valves, aiming to manage the tip leakage flow in turbines. In this paper, Tesla valves are applied to the tip of a high load turbine blade, and the effectiveness is investigated. This paper analyzes the flow field characteristics, the composition of the vortices, and the loss distribution to understand the working principle of this method. Furthermore, the paper delves into the specific effects of various Tesla valve configurations on the aerodynamic performance of the blade. This study reveals that the unique branching design of Tesla valves creates resistance for the fluid. Due to Tesla valves being machined into the blade tip as grooves, this kind of resistance generates vortices when the leakage flow is obstructed by the grooves. The existence of these vortices disrupts the leakage flow in the upper clearance. Compared to a flat blade tip cascade (Case 1), when Tesla valves are arranged in the crosswise direction (Case 2), perpendicular to the pressure side (Case 3), and in specific orientations aligned with the leakage flow direction (Cases 4–6), the total leakage flow rate is reduced by 4.8 %, 5.9 %, 3.6 %, 5.1 %, and 6.2 % respectively, while the total pressure loss is decreased by 0.7 %, 1.4 %, 4.8 %, 6.8 %, and 8.3 % respectively. Additionally, the paper investigates the effect of the Tesla-valve tip at various incidence angles. The results indicate that Tesla valves effectively reduce the blade tip leakage flow rate and weaken the strength of the tip leakage vortex (TLV) at different incidence angles. The novelty of this study is that this new tip leakage control technology effectively utilizes the unidirectional flow characteristics of the Tesla valve, which has a significant hindrance to the leakage fluid of the turbine tip, reduces the leakage flow rate, and improves the aerodynamic performance of the turbine blade.