HPT Blade Research Articles

Effect of Blowing Ratio on Turbine Blade Air Film Cooling Under Different Engine Conditions

Under different working conditions of the aeroengine, the rotating speed of the turbine blades is diverse, and this causes the high-temperature gas mainstream to impact the turbine blades at disparate angles of attack. In order to explore the film cooling mechanism of the pressure surface and suction surface of aeroengine turbine blade at unusual speed, a 3D model of the turbine blades and internal runners is constructed, which refers to Pratt & Whitney PW4084 primary HPT blade. In this model, the high-temperature gas mainstream is set to attack the turbine blades through three distinct angles, the turbine blade air film cooling model is established, and the numerical simulation is conducted at the different blowing ratios. The results showed that the angle of impact (rotational speed) is the key factor affecting the cooling efficiency of the blade. The cooling effect of the suction surface is the best under the positive attack, however, the cooling effect of the pressure surface under the negative attack angle is the first-rate. With the increase of the speed, the surface temperature of the top and tail of the blade pressure surface will gradually decrease, and as the speed reduces, the surface temperature of the lower part of the suction surface of the blade will slightly increase. Finally, under three different attack angles, the cooling efficiency of the air film on the surface of the blade will augment with the increase of the blowing ratio.

Borescope inspection for HPT blade of CFM56-7B engine

CFM56-7B engine has had several ruptures of HPT blades since its service, resulting engine failure during the flight. Through borescope inspection for HPT blade can detect the damage of blade on the front and rear edge effectively, and avoid the use of damaged blades. This paper briefly summarizes the experiences of borescope inspection for HPT blade, mainly using hose to check the defect of leading edge for blade.

The Radial Displacement of the HPT Blade under the Effects of the Temperature Field and the Centrifugal

The blade temperature field is computed using the finite element software of ANSYS and Hypermesh. The radial displacement response under the temperature field and centrifugal is analyzed. And a new method of plotting the grid and loading the boundary for complicated three-dimensional model in the finite element software is advanced. The heat transfer coefficients at different parts of the blade are introduced. The results show that for the temperature circumference distribution of the blade profile, the temperature is the highest at the leading and trailing edges and low at the middle. For the radial distribution the temperature is low at the blade root, and high at the blade profile and the integral tip shroud. The effect of temperature field is the main reason of the blade radial displacement while the centrifugal effect accounts for little.

Microstructural characterization of thermal barrier coatings on high pressure turbine blades

Thermal barrier coated high pressure turbine blades were characterized before and after the service by microstructural analysis and Cr 3+ photostimulated luminescence piezo-spectroscopy. Thermal barrier coatings, in this study, consisted of electron beam physical vapor deposited yttria partially stabilized zirconia (YSZ; ZrO 2–8 wt.% Y 2O 3), vapor-deposited aluminide bond coat and Ni-base superalloy. Compressive residual stress in thermally grown oxide, measured by Cr 3+ photostimulated luminescence piezo-spectroscopy, was observed to be in the order of 2.5∼3.0 GPa and varied slightly as a function of substrate geometry. X-Ray diffraction and scanning electron microscopy equipped with energy dispersive X-ray spectroscopy were utilized to investigate the microstructural development of thermal barrier coatings. The as-deposited non-equilibrium tetragonal ( t′) phase in the YSZ coatings was observed to decompose after the service, but the monoclinic ( m) phase was only found in the YSZ coatings with concave substrate curvature on the pressure side of the HPT blade. Also, a significant sintering of ZrO 2–8 wt.% Y 2O 3 coating after the service was observed in the microstructure. Localized spallation of YSZ occurred within the thermally grown oxide (mostly α-Al 2O 3) and within the ZrO 2–8 wt.% Y 2O 3 coating for pressure and suction sides of the serviced high pressure turbine blade near the tip, respectively.