scholarly journals Machining of a film-cooling hole in a single-crystal superalloy by high-speed electrochemical discharge drilling

2016 ◽  
Vol 29 (2) ◽  
pp. 560-570 ◽  
Author(s):  
Yan Zhang ◽  
Zhengyang Xu ◽  
Yun Zhu ◽  
Di Zhu
Keyword(s):  
Single Crystal ◽  
Film Cooling ◽  
High Speed ◽  
Single Crystal Superalloy ◽  
Electrochemical Discharge ◽  
Cooling Hole

scholarly journals Effect of different drilling techniques on high-cycle fatigue behavior of nickel-based single-crystal superalloy with film cooling hole

2021 ◽  
Vol 40 (1) ◽  
pp. 121-130
Author(s):  
Zhijin Zhang ◽  
Mingqi Zhang
Keyword(s):  
Single Crystal ◽  
Fatigue Limit ◽  
Film Cooling ◽  
High Cycle Fatigue ◽  
Great Influence ◽  
Single Crystal Superalloy ◽  
Ambient Atmosphere ◽  
Cycle Fatigue ◽  
Single Hole ◽  
Cooling Hole

Abstract The flat plate specimens of nickel-based single-crystal superalloy with 14 film cooling holes, which made by different drilling techniques, were used to study the high-cycle fatigue (HCF) properties at 980°C in an ambient atmosphere. At the same time, the electrical discharge machining (EDM) specimens with a single hole were also used to study the HCF properties under different temperatures. The hole and fracture micrographs were analyzed by scanning electron microscope. The results indicated that different drilling techniques have a great influence on HCF life. The fatigue limit of the millisecond laser drilling is 353 MPa, while the EDM is 359 MPa and the electro-stream machining (ESM) is 378 MPa. The fatigue life decreases gradually with the temperature increasing. The fatigue limit of EDM specimens with a single hole at 900°C, 980°C, and 1,050°C are 472, 430, and 293 MPa, respectively. The destruction of the specimens is a typical multisource rupture, and the fracture morphology includes three parts: the cracks sources around the film cooling hole, the propagation zone along the {001} planes, and instant rupture zone along the {111} planes.

Experimental Investigation Into the Impact of Crossflow on the Coherent Unsteadiness Within Film Cooling Flows

2011 ◽  
Author(s):  
Richard J. Fawcett ◽  
Andrew P. S. Wheeler ◽  
Li He ◽  
Rupert Taylor
Keyword(s):  
Film Cooling ◽  
High Speed ◽  
High Speed Photography ◽  
Cooling Flows ◽  
Pressure Surface ◽  
Cooling Flow ◽  
Cooling Hole ◽  
Crossflow Velocity ◽  
The Impact ◽  
First Time

It is known that the mixing of a film cooling flow with the main turbine passage flow is an unsteady process, with coherent unsteady features occurring across a range of blowing ratios. Upon an aero engine the cooling holes on a turbine blade commonly have a crossflow at the hole inlet. Previous work has shown that crossflow at the hole inlet modifies the time-mean flowfield downstream of a cooling hole compared to the case without crossflow. The current paper investigates the impact of spanwise orientated crossflow on the coherent unsteadiness within film cooling flows. Both cylindrical and fan-shaped holes, located on a blade pressure surface, are studied. The range of blowing ratios considered is 0.7 to 1.8 and the crossflow velocity is up to 0.8 times the bulk jet velocity. High Speed Photography and Hot Wire Anemometry are used to observe the presence of coherent unsteadiness, both immediately downstream of the hole exit and within the cooling hole tube. The results show that the coherent unsteadiness downstream of the hole exit is persistent and its occurrence is not significantly affected by the magnitude of spanwise crossflow. Within the cooling hole tube the existence of coherent unsteadiness is presented for the first time, inside both cylindrical and fan-shaped holes, with a Strouhal number of 0.6 to 0.8. The pattern of this in-hole coherent unsteadiness is seen to change with increasing the crossflow velocity.

Application of S-PIV for Investigation of Round and Shaped Film Cooling Holes at High Density Ratios

2016 ◽  
Author(s):  
Travis B. Watson ◽  
Sara Nahang-Toudeshki ◽  
Lesley M. Wright ◽  
Daniel C. Crites ◽  
Mark C. Morris ◽  
...  
Keyword(s):  
Film Cooling ◽  
High Speed ◽  
Density Ratio ◽  
High Density ◽  
Round Hole ◽  
Turbine Engine ◽  
Flow Vorticity ◽  
Cooling Hole ◽  
Shaped Hole ◽  
Density Ratios

Hot section turbine engine components are often cooled through the use of a cool film of air on the component wall. The source of the air used for film cooling comes from the compressor of the gas turbine engine and may be 800°C, or more, cooler than the hot gas path air. The temperature differential between the hot mainstream gas and the film coolant results in a large difference in density between the two gases. In order to investigate the effect of high density ratios on film cooling performance, a traditional, round hole (θ = 30°) and a laidback, fan shaped hole (θ = 30°, α = γ = 10°) were observed using Stereo-Particle Image Velocimetry (S-PIV). Flowfield measurements were performed on various planes downstream of the film cooling hole (x/d = 0, 1, 3 and 10 for the round hole and x/d = 0, 3, and 10 for the shaped hole). At each location the coolant-to-mainstream interaction was captured at multiple density ratios (DR = 1, 2, 3, 4) and blowing ratios (M = 0.5, 1.0, 1.5). Using S-PIV, the three-dimensional flow field was measured. Distributions of the flow vorticity were derived from the high speed velocity measurements taken during S-PIV testing. For the simple angle, round holes, the results show at the elevated density ratios, the coolant spreads laterally near the hole; while at DR = 1, the coolant trace is limited to the width of the film cooling hole. Furthermore, as the cooling jet exits from the round hole, the vorticity within the jet is very strong, leading to increased mixing with the mainstream. However, as the density ratio increases (at a given blowing ratio), this mixing was reduced. For a given flow condition, the rotation was reduced with the jet exiting the shaped hole (compared to the round hole), and this led to enhanced protection on the surface. While investigating both round and shaped holes, it was shown the S-PIV method is a valuable tool to observe and quantify the jet–to–mainstream interactions near the film cooled surface.

Film Effectiveness Performance of an Arrowhead-Shaped Film Cooling Hole Geometry

2006 ◽  
Author(s):  
Yoji Okita ◽  
Masakazu Nishiura
Keyword(s):  
Film Cooling ◽  
High Speed ◽  
Large Scale ◽  
Lateral Direction ◽  
Numerical Work ◽  
Pressure Surface ◽  
Pressure Sensitive ◽  
Cooling Hole ◽  
Hole Geometry ◽  
Effectiveness Data

This paper presents the first experimental and numerical work of film effectiveness performance for a novel film cooling method with an arrowhead-shaped hole geometry. Experimental results demonstrate that the proposed hole geometry improves the film effectiveness on both suction and pressure surface of a generic turbine airfoil. Film effectiveness data for a row of the holes are compared with that of fan-shaped holes at the same inclination angle of 35° to the surface on a large-scale airfoil model at engine representative Reynolds number and Mach number in a high speed tunnel with moderately elevated temperature mainstream flow. The film effectiveness data are collected using pressure sensitive paint (PSP). Numerical results show that the coolant film with the proposed hole geometry remains well attached to the surface and diffuses in the lateral direction in comparison with the conventional laidback fan-shaped holes for coolant to mainstream blowing ratios of 0.6 to 3.5.

Film Effectiveness Performance of an Arrowhead-Shaped Film-Cooling Hole Geometry

2006 ◽  
Vol 129 (2) ◽  
pp. 331-339 ◽  
Author(s):  
Yoji Okita ◽  
Masakazu Nishiura
Keyword(s):  
Film Cooling ◽  
High Speed ◽  
Large Scale ◽  
Lateral Direction ◽  
Numerical Work ◽  
Pressure Surface ◽  
Pressure Sensitive ◽  
Cooling Hole ◽  
Hole Geometry ◽  
Effectiveness Data

This paper presents the first experimental and numerical work of film effectiveness performance for a novel film-cooling method with an arrowhead-shaped hole geometry. Experimental results demonstrate that the proposed hole geometry improves the film effectiveness on both suction and pressure surface of a generic turbine airfoil. Film effectiveness data for a row of the holes are compared to that of fan-shaped holes at the same inclination angle of 35 deg to the surface on a large-scale airfoil model at engine representative Reynolds number and Mach number in a high-speed tunnel with moderately elevated temperature mainstream flow. The film effectiveness data are collected using pressure-sensitive paint. Numerical results show that the coolant film with the proposed hole geometry remains well attached to the surface and diffuses in the lateral direction in comparison with the conventional laidback fan-shaped holes for coolant to mainstream blowing ratios of 0.6–3.5.

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