Upstream and Downstream Step Curvature Effects on Film Cooling Effectiveness and Flow Structures

2015 ◽  
Vol 40 (12) ◽  
pp. 3697-3707 ◽  
Author(s):  
Fifi N. M. Elwekeel ◽  
Antar M. M. Abdala ◽  
Diangui Huang
Keyword(s):  
Film Cooling ◽  
Flow Structures ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Curvature Effects

scholarly journals Investigations on the effect of different influencing factors on film cooling effectiveness under the injection of synthetic coolant

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jianlong Chang ◽  
Xinlei Duan ◽  
Yang Du ◽  
Baoquan Guo ◽  
Yutian Pan
Keyword(s):  
Film Cooling ◽  
Elliptical Hole ◽  
Synthetic Jet ◽  
Cooling Effect ◽  
Flow Structures ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Flow ◽  
Cooling Method ◽  
Strong Controllability

AbstractBy combining the synthetic jet and film cooling, the incident cooling flow is specially treated to find a better film cooling method. Numerical simulations of the synthetic coolant ejected are carried out for analyzing the cooling performance in detail, under different blowing ratios, hole patterns, Strouhal numbers, and various orders of incidence for the two rows of holes. By comparing the flow structures and the cooling effect corresponding to the synthetic coolant and the steady coolant fields, it is found that within the scope of the investigations, the best cooling effect can be obtained under the incident conditions of an elliptical hole with the aspect ratio of 0.618, the blow molding ratio of 2.5, and the Strouhal number St = 0.22. Due to the strong controllability of the synthetic coolant, the synthetic coolant can be controlled through adjusting the frequency of blowing and suction, so as to change the interaction between vortex structures for improving film cooling effect in turn. As a result, the synthetic coolant ejection is more advisable in certain conditions to achieve better outcomes.

Effect of Unheated Starting Lengths on Film Cooling Experiments

2006 ◽  
Vol 128 (3) ◽  
pp. 579-588 ◽  
Author(s):  
Sarah M. Coulthard ◽  
Ralph J. Volino ◽  
Karen A. Flack
Keyword(s):  
Film Cooling ◽  
Infrared Camera ◽  
Stanton Number ◽  
Flow Structures ◽  
Transfer Coefficients ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Single Row ◽  
Heat Transfer Coefficients ◽  
Film Cooling Holes

The effect of an unheated starting length upstream of a row of film cooling holes was studied experimentally to determine its effect on heat transfer coefficients downstream of the holes. Cases with a single row of cylindrical film cooling holes inclined at 35deg to the surface of a flat plate were considered at blowing ratios of 0.25, 0.5, 1.0, and 1.5. For each case, experiments were conducted to determine the film-cooling effectiveness and the Stanton number distributions in cases with the surface upstream of the holes heated and unheated. Measurements were made using an infrared camera, thermocouples, and hot and cold-wire anemometry. Ratios were computed of the Stanton number with film cooling (Stf) to corresponding Stanton numbers in cases without film cooling (Sto), but the same surface heating conditions. Contours of these ratios were qualitatively the same regardless of the upstream heating conditions, but the ratios were larger for the cases with a heating starting length. Differences were most pronounced just downstream of the holes and for the lower blowing rate cases. Even 12 diameters downstream of the holes, the Stanton number ratios were 10–15% higher with a heated starting length. At higher blowing rates the differences between the heated and unheated starting length cases were not significant. The differences in Stanton number distributions are related to jet flow structures, which vary with blowing rate.

Digital Geometry and Morphing to Support Analysis and Design

2018 ◽  
Author(s):  
N. Meah ◽  
M. Hunt ◽  
R. Evans ◽  
T. Racz ◽  
J. Verdicchio ◽  
...  
Keyword(s):  
Film Cooling ◽  
Flow Simulation ◽  
Vortical Flow ◽  
Flow Structures ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Analysis And Design ◽  
Wide Range ◽  
Cooling Hole ◽  
Film Cooling Holes

This paper describes the application of geometry morphing, integrated with meshing and flow simulation, to the topological optimisation of gas turbine film cooling holes. Using a Genetic Algorithm to manage the digitally represented geometry a wide range of novel cooling hole shapes can be generated and useful improvements in film cooling effectiveness are observed. The simulations suggest that modified vortical flow structures are responsible for improved coolant distribution and coverage at hole exit.

Numerical Simulation of Film Cooling on Rotating Blade Tips Within a High-Pressure Turbine

2013 ◽  
Author(s):  
K. Lu ◽  
M. T. Schobeiri ◽  
J. C. Han
Keyword(s):  
High Pressure ◽  
Film Cooling ◽  
Flow Structures ◽  
Research Facility ◽  
High Pressure Turbine ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Rotating Blade ◽  
Blade Tip ◽  
Blade Tips

This paper numerically investigates the aerodynamics and film cooling effectiveness of high pressure turbine blade tips. Two different rotor blade tip configurations have been studied: the plane tip with tip hole cooling and the squealer tip with tip hole cooling. The geometry of the blades is determined based on the blade profiles within the three-stage multi-purpose turbine research facility at the Turbomachinery Performance and Flow Research Laboratory (TPFL), Texas A&M University. Seven perpendicular holes along the camber line are used for the tip hole cooling. The clearance between the blade tip and casing is 1.0% of the blade span. For each blade tip configuration, the coolant is ejected through the cooling holes under blowing ratios of M = 0.5, 1.0 and 1.5. In this paper, a comparison between the plane tip and the squealer tip has been presented. The detailed flow structures and film cooling effectiveness are discussed.

Effect of Unheated Starting Lengths on Film Cooling Experiments

2005 ◽  
Author(s):  
Sarah M. Coulthard ◽  
Ralph J. Volino ◽  
Karen A. Flack
Keyword(s):  
Film Cooling ◽  
Infrared Camera ◽  
Stanton Number ◽  
Flow Structures ◽  
Transfer Coefficients ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Single Row ◽  
Heat Transfer Coefficients ◽  
Film Cooling Holes

The effect of an unheated starting length upstream of a row of film cooling holes was studied experimentally to determine its effect on heat transfer coefficients downstream of the holes. Cases with a single row of cylindrical film cooling holes inclined at 35 degrees to the surface of a flat plate were considered at blowing ratios of 0.25, 0.5, 1.0 and 1.5. For each case experiments were conducted to determine the film cooling effectiveness and the Stanton number distributions in cases with the surface upstream of the holes heated and unheated. Measurements were made using an infrared camera, thermocouples, and hot and cold wire anemometry. Ratios were computed of the Stanton number with film cooling (Stf) to corresponding Stanton numbers in cases without film cooling (Sto) but the same surface heating conditions. Contours of these ratios were qualitatively the same regardless of the upstream heating conditions, but the ratios were larger for the cases with a heating starting length. Differences were most pronounced just downstream of the holes and for the lower blowing rate cases. Even 12 diameters downstream of the holes the Stanton number ratios were 10 to 15% higher with a heated starting length. The differences in Stanton number distributions are related to jet flow structures which vary with blowing rate.

A Sector-Cascade Test Rig for Measurements of Heat Transfer in Turbine Center Frames

2020 ◽  
Author(s):  
Patrick R. Jagerhofer ◽  
Marios Patinios ◽  
Gerhard Erlacher ◽  
Tobias Glasenapp ◽  
Emil Göttlich ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Axial Length ◽  
Film Cooling ◽  
Flow Structures ◽  
Test Rig ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Mainstream Flow

Abstract The turbine center frame (TCF) is an inherent component of turbofan aircraft engines and is used for connecting the high-pressure turbine (HPT) to the low-pressure turbine (LPT). Its position immediately downstream of the HPT makes it susceptible to the extremely high temperatures of future engines. Despite this, fundamental knowledge of heat transfer in TCFs and the influencing factors is still missing. This paper presents a new 45° sector-cascade test rig specifically designed for fundamental studies of film cooling effectiveness and heat transfer coefficient in TCFs and for the development and validation of a measurement technique involving infrared thermography and heating foils. Measurements of heat transfer coefficient in the TCF were taken for two purge-to-mainstream mass flow ratios corresponding to the case of no purge and nominal (to engine operation) purge. The magnitude of the heat transfer coefficients on the hub and strut surfaces was highly influenced by the various flow structures in the passage and by the velocity variation of the mainstream flow due to the “aggressive” design of the TCF. Heat transfer on the surface of the strut was mainly governed by boundary layer behavior (laminar near the leading edge and turbulent for the rest of the strut) augmented by the effect of the secondary flow structures. Measurements of film cooling effectiveness were also taken for the single case of nominal purge. A region of high film cooling effectiveness was observed, extending from the purge cavity exit to about 40% of the passage axial length. In this region, the effectiveness decreased with increasing axial length. On the surface of the struts and fillet radii the film cooling effectiveness was found to be zero. This was attributed to the effect of the horse-shoe vortex which sweeps the purge flow away from the strut surface and dilutes it by continuously entraining hot mainstream flow.

A SECTOR-CASCADE TEST RIG FOR MEASUREMENTS OF HEAT TRANSFER IN TURBINE CENTER FRAMES

2021 ◽  
pp. 1-15
Author(s):  
Patrick René Jagerhofer ◽  
Marios Patinios ◽  
Gerhard Erlacher ◽  
Tobias Glasenapp ◽  
Emil Goettlich ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Axial Length ◽  
Film Cooling ◽  
Flow Structures ◽  
Test Rig ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Mainstream Flow

Abstract This paper presents a new 45° sector-cascade test rig specifically designed for fundamental studies of film cooling effectiveness and heat transfer coefficient in Turbine Center Frames (TCFs) and for the development and validation of a measurement technique involving infrared thermography and heating foils. Measurements of heat transfer coefficient in the TCF were taken for two purge-to-mainstream mass flow ratios corresponding to the case of no purge and nominal (to engine operation) purge. The magnitude of the heat transfer coefficients on the hub and strut surfaces was highly influenced by the various flow structures in the passage and by the velocity variation of the mainstream flow due to the “aggressive” design of the TCF. Heat transfer on the surface of the strut was mainly governed by boundary layer behavior (laminar near the leading edge and turbulent for the rest of the strut) augmented by the effect of the secondary flow structures. Measurements of film cooling effectiveness were also taken for the single case of nominal purge. A region of high film cooling effectiveness was observed, extending from the purge cavity exit to about 40% of the passage axial length. In this region, the effectiveness decreased with increasing axial length. On the surface of the struts and fillet radii the film cooling effectiveness was found to be zero. This was attributed to the effect of the horse-shoe vortex which sweeps the purge flow away from the strut surface and dilutes it by continuously entraining hot mainstream flow.

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