Effects of cone angle formed by single-side and double-side laser machining on the aerothermal performance for a plate with multi-rows cooling holes

Laser processing has emerged as a novel technique for efficiently manufacturing film‑cooling holes with low sensitivity to materials. However, it inevitably leads to cone angle formation due to the heat‑affected zone issue, especially when machining ceramic matrix composites. This study focuses on two types of holes with cone angles manufactured by single‑side and double‑side processing approaches. Utilizing the pressure‑sensitive paint experimental technique and numerical simulation methods, the aerodynamic characteristics of a multi‑row film‑cooling hole flat‑plate configuration based on cone angles are investigated. Results indicate that for single‑side processed holes, a larger cone angle can enhance cooling effectiveness, but a maximum effectiveness exists that is constrained by the blowing ratio ( BR ). When the cone angle is below 6°, cooling effectiveness decreases with BR increasing, whereas the opposite trend is observed for cone angles greater than 6°. Variations in the cone angle significantly affect the spanwise‑averaged cooling effectiveness distribution downstream of the last row of holes. Increasing of the cone angle leads to the formation of a stronger downstream‑biased vortex inside the hole, thereby reducing momentum of the exit. For double‑side machined holes, vortex formation inside the hole is suppressed, and the coolant momentum tends to dissipate in the mainstream region above the hole. Raising the machining interface allows a relatively low rate of effectiveness decay to be maintained downstream of the last row, thereby reducing the sensitivity of cooling effectiveness to variations in the cone angle.