Film cooling characteristics of squealer tip of a turbine blade

Abstract

The high-speed and high-temperature gap leakage flow in the turbine blade tip clearance directly scours the tip of the rotor blade and generates a local high-temperature region, so the active and passive control of the gap leakage flow is very important. Based on the pressure sensitive paint (PSP) experiment, the effects of density ratio, blowing ratio, and clearance height on the film cooling characteristics of the squealer blade tip were studied. The results show that with the increase of the density ratio, the film-cooling effectiveness of the squealer blade tip gradually increases, especially in the large clearance height, and the average cooling effect of the blade tip is increased by 35%. The effect of tip clearance height and blowing ratio on the tip surface cooling effect is not single. Under the condition of small tip clearance, the tip surface film-cooling effectiveness increases with the increase of the blowing ratio. Under the condition of large tip clearance, the tip surface film-cooling effectiveness decreases first and then increases with the increase of blowing ratio. At the same time, when the blowing ratio is small, the increase in tip clearance height improves the tip trailing edge area and the film-cooling effectiveness around the holes, and the average cooling effect of the blade tip surface increases by 6.85 %.

Keywords

• squealer tip of a turbine blade
• clearance height
• blowing ratio
• density ratio
• film-cooling effectiveness