Numerical Simulation of Swirling Impinging Jet Issuing from a Threaded Hole under Inclined Condition

Area of Science:

• * Turbomachinery and Thermal Engineering
• * Computational Fluid Dynamics (CFD) and Heat Transfer

Background:

• * Gas turbine blades require effective cooling, particularly at the leading edge, to withstand high operating temperatures.
• * Traditional cooling structures often use inclined round holes, which have limitations in heat transfer efficiency.

Purpose of the Study:

• * To investigate the heat transfer and fluid flow characteristics of swirling impinging jets (SIJ) from inclined threaded holes.
• * To compare the cooling performance of threaded holes against traditional round holes in gas turbine blade leading edges.
• * To analyze the influence of jet inclination angle, jet-to-plate distance, and Reynolds number on SIJ performance.

Main Methods:

• * Numerical simulation of swirling impinging jets (SIJ) issuing from 45° threaded holes under inclined conditions.
• * Parametric study involving jet inclination angle (45°-90°), jet-to-plate distance (H/d = 2, 4, 6), and Reynolds number (6000-24,000).

Main Results:

• * Inclination angle and jet-to-plate distance significantly influence vortex structures; Reynolds number has minimal impact.
• * Swirling impinging jets from threaded holes show superior impinging cooling compared to circular impinging jets (CIJ).
• * Heat transfer degrades at 45° inclination but improves for angles >45° with threaded holes, particularly within r/d < 3.

Conclusions:

• * Threaded holes offer enhanced heat transfer in inclined conditions for gas turbine blade cooling.
• * Optimal cooling is achieved with SIJ at inclination angles greater than 45°, outperforming round holes.
• * Increasing Reynolds number enhances heat transfer up to Re = 18,000, after which the enhancement rate diminishes.