Measurements of Adiabatic Effectiveness from Full Coverage Film Cooling on a Scaled Turbine Vane with Laidback Fanshaped Holes PDF Download
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Author: Owen Michael O'Neal Publisher: ISBN: Category : Languages : en Pages : 206
Book Description
This study was focused on measurements of adiabatic effectiveness on a scaled turbine vane which made use of a contoured endwall to match engine conditions. The vane model featured a full coverage film-cooling configuration with five rows of cylindrical holes in the showerhead and ten rows of laidback fanshaped holes distributed on the pressure and suction sides. The vane model was tested across a wide range of blowing ratios in several different coolant configurations including: individual rows on the pressure and suction side, full coverage tests with and without showerhead cooling, and full coverage tests at low and high mainstream turbulence levels. Comparisons between these configurations were made in order to assess the effects of local curvature, showerhead cooling, and mainstream turbulence levels. Single row tests measured in areas of high convex curvature tended to have an improved performance relative to flat plate predictions, while the opposite was true for rows in areas of concave curvature. Overall, showerhead cooling did not provide any significant improvements in effectiveness far downstream on both the pressure and suction side. Increasing mainstream turbulence levels tended to diminish the film cooling effectiveness. The negative effect of higher mainstream turbulence was most significant at low blowing ratios, but became negligible at higher flow rates.
Author: Owen Michael O'Neal Publisher: ISBN: Category : Languages : en Pages : 206
Book Description
This study was focused on measurements of adiabatic effectiveness on a scaled turbine vane which made use of a contoured endwall to match engine conditions. The vane model featured a full coverage film-cooling configuration with five rows of cylindrical holes in the showerhead and ten rows of laidback fanshaped holes distributed on the pressure and suction sides. The vane model was tested across a wide range of blowing ratios in several different coolant configurations including: individual rows on the pressure and suction side, full coverage tests with and without showerhead cooling, and full coverage tests at low and high mainstream turbulence levels. Comparisons between these configurations were made in order to assess the effects of local curvature, showerhead cooling, and mainstream turbulence levels. Single row tests measured in areas of high convex curvature tended to have an improved performance relative to flat plate predictions, while the opposite was true for rows in areas of concave curvature. Overall, showerhead cooling did not provide any significant improvements in effectiveness far downstream on both the pressure and suction side. Increasing mainstream turbulence levels tended to diminish the film cooling effectiveness. The negative effect of higher mainstream turbulence was most significant at low blowing ratios, but became negligible at higher flow rates.
Author: James R. Winka Publisher: ISBN: Category : Languages : en Pages : 246
Book Description
A series of experiments were carried out to measure the effects of convex surface curvature on film cooling. In the first series of experiments cooling holes were positioned along the vane such that their non-dimensional curvature parameter, 2r/d, was matched. Single row of holes with the same diameter were placed at high and moderate curvature position along a turbine vane resulting in 2r/d = 28 and 40, accordingly. A third row of holes was installed on the vane at the same location as the moderate curvature row with a larger hole diameter, resulting in 2r/d = 28, matching the high curvature row. Adiabatic temperature measurements were then carried out for blowing ratios of M = 0.30 to 1.60 tested at a density ratio of DR = 1.20. The results indicated that there was some scaling of performance present with matching 2r/d, but there was not an exact matching of performance. The second series of experiments focused on the effects of a changing surface curvature downstream of injection. Two row of holes were positioned along the vane surface such that the local radius of curvature and hole diameters were equivalent, with one row positioned upstream of the maximum curvature point and the other downstream of the maximum curvature point. Adiabatic temperature measurements were carried out for blowing ratios of M = 0.30 to 1.60 and tested at a density ratio of DR = 1.20. The results show that the change in curvature downstream plays a significant role in the performance of film cooling and that the local surface curvature is insufficient in capturing its effects. Additional experiments were carried out to measure the effects of the approaching boundary layer influence on film cooling as well as the effect of injection angle at a weakly convex surface.
Author: Randall Paul Williams Publisher: ISBN: Category : Languages : en Pages : 258
Book Description
A scaled-up gas turbine vane model was constructed in such a way to achieve a Biot number (Bi) representative of an actual engine component, and experiments were performed to collect temperature data which may be used to validate computational fluid dynamics (CFD) codes used in the design of gas turbine cooling schemes. The physical model incorporated an internal impingement plate to provide cooling on the inner wall surface, and film cooling over the external surface was provided by a single row of holes located on the suction side of the vane. A single row of holes was chosen to simplify the operating condition and test geometry for the purpose of evaluating CFD predictions. Thermocouples were used to measure internal gas temperatures and internal surface temperatures over a range of coolant flow rates, while infra-red thermography was used to measure external surface temperatures. When Bi is matched to an actual engine component, these measured temperatures may be normalized relative to the coolant temperature and mainstream gas temperature to determine the overall cooling effectiveness, which will be representative of the real engine component. Measurements were made to evaluate the overall effectiveness resulting from internal impingement cooling alone, and then with both internal impingement cooling and external film cooling as the coolant flow rate was increased. As expected, with internal impingement cooling alone, both internal and external wall surfaces became colder as the coolant flow rate was increased. The addition of film cooling further increased the overall effectiveness, particularly at the lower and intermediate flow rates tested, but provided little benefit at the highest flow rates. An optimal jet momentum flux ratio of I=1.69 resulted in a peak overall effectiveness, although the film effectiveness was shown to be low under these conditions. The effect of increasing the coolant-to-mainstream density ratio was evaluated at one coolant flow rate and resulted in higher values of overall cooling effectiveness and normalized internal temperatures, throughout the model. Finally, a 1-dimensional heat transfer analysis was performed (using a resistance analogy) in which overall effectiveness with film cooling was predicted from measurements of film effectiveness and overall effectiveness without film cooling. This analysis tended to over-predict overall effectiveness, at the lowest values of the jet momentum flux ratio, while under-predicting it at the highest values.
Author: Owen Michael O'Neal
Author: Owen Michael O'Neal
Author: Mark Kenneth Harrington
Author: M. Gritsch
Author: S. Yavuzkurt
Author: James W. Gauntner
Author: James R. Winka
Author: Marcus Damian Polanka
Author: 
Author: Atul Kohli
Author: Randall Paul Williams