Variable Fidelity Optimization of Film Cooling Hole Arrangement Considering Internal Cooling Effects

2017 ◽  
Author(s):  
Yoonki Kim ◽  
Sang-A Lee ◽  
Jinuk Kim ◽  
Dong-Ho Rhee ◽  
Kwanjung Yee
Keyword(s):  
Film Cooling ◽  
Internal Cooling ◽  
Cooling Hole ◽  
Variable Fidelity ◽  
Cooling Effects

Combined Experimental and CFD Study of a HP Blade Multi-Pass Cooling System

2009 ◽  
Author(s):  
D. Jackson ◽  
P. Ireland ◽  
B. Cheong
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Cooling System ◽  
Detailed Comparison ◽  
Bulk Temperature ◽  
Internal Cooling ◽  
3 Dimensional ◽  
Turbine Cooling ◽  
Cooling Hole ◽  
The Difference

Progress in the computing power available for CFD predictions now means that full geometry, 3 dimensional predictions are now routinely used in internal cooling system design. This paper reports recent work at Rolls-Royce which has compared the flow and htc predictions in a modern HP turbine cooling system to experiments. The triple pass cooling system includes film cooling vents and inclined ribs. The high resolution heat transfer experiments show that different cooling performance features are predicted with different levels of fidelity by the CFD. The research also revealed the sensitivity of the prediction to accurate modelling of the film cooling hole discharge coefficients and a detailed comparison of the authors’ computer predictions to data available in the literature is reported. Mixed bulk temperature is frequently used in the determination of heat transfer coefficient from experimental data. The current CFD data is used to compare the mixed bulk temperature to the duct centreline temperature. The latter is measured experimentally and the effect of the difference between mixed bulk and centreline temperature is considered in detail.

scholarly journals Reduction in Flow Parameter Resulting From Volcanic Ash Deposition in Engine Representative Cooling Passages

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Sebastien Wylie ◽  
Alexander Bucknell ◽  
Peter Forsyth ◽  
Matthew McGilvray ◽  
David R. H. Gillespie
Keyword(s):  
Film Cooling ◽  
Volcanic Ash ◽  
Flow Parameter ◽  
Cooling System ◽  
Pressure Ratio ◽  
Turbine Blades ◽  
Metal Temperature ◽  
Internal Cooling ◽  
Cooling Hole ◽  
Cooling Passage

Internal cooling passages of turbine blades have long been at risk to blockage through the deposition of sand and dust during fleet service life. The ingestion of high volumes of volcanic ash (VA) therefore poses a real risk to engine operability. An additional difficulty is that the cooling system is frequently impossible to inspect in order to assess the level of deposition. This paper reports results from experiments carried out at typical high pressure (HP) turbine blade metal temperatures (1163 K to 1293 K) and coolant inlet temperatures (800 K to 900 K) in engine scale models of a turbine cooling passage with film-cooling offtakes. Volcanic ash samples from the 2010 Eyjafjallajökull eruption were used for the majority of the experiments conducted. A further ash sample from the Chaiten eruption allowed the effect of changing ash chemical composition to be investigated. The experimental rig allows the metered delivery of volcanic ash through the coolant system at the start of a test. The key metric indicating blockage is the flow parameter (FP), which can be determined over a range of pressure ratios (1.01–1.06) before and after each experiment, with visual inspection used to determine the deposition location. Results from the experiments have determined the threshold metal temperature at which blockage occurs for the ash samples available, and characterize the reduction of flow parameter with changing particle size distribution, blade metal temperature, ash sample composition, film-cooling hole configuration and pressure ratio across the holes. There is qualitative evidence that hole geometry can be manipulated to decrease the likelihood of blockage. A discrete phase computational fluid dynamics (CFD) model implemented in Fluent has allowed the trajectory of the ash particles within the coolant passages to be modeled, and these results are used to help explain the behavior observed.

The Effects of Vane Showerhead Injection Angle and Film Compound Angle on Nozzle Endwall Cooling (Phantom Cooling)

2014 ◽  
Vol 137 (2) ◽  
Author(s):  
Luzeng Zhang ◽  
Juan Yin ◽  
Hee Koo Moon
Keyword(s):  
Film Cooling ◽  
Suction Side ◽  
Nitrogen Gas ◽  
Injection Angle ◽  
Test Models ◽  
Cooling Hole ◽  
Cooling Effects ◽  
Film Cooling Holes ◽  
Compound Angle ◽  
Endwall Cooling

The effects of airfoil showerhead (SH) injection angle and film-cooling hole compound angle on nozzle endwall cooling (second order film-cooling effects, also called "phantom cooling") were experimentally investigated in a scaled linear cascade. The test cascade was built based on a typical industrial gas turbine nozzle vane. Endwall surface phantom cooling film effectiveness measurements were made using a computerized pressure sensitive paint (PSP) technique. Nitrogen gas was used to simulate cooling flow as well as a tracer gas to indicate oxygen concentration such that film effectiveness can be obtained by the mass transfer analogy. Two separate nozzle test models were fabricated, which have the same number and size of film-cooling holes but different configurations. One had a SH angle of 45 deg and no compound angles on the pressure and suction side (SS) film holes. The other had a 30 deg SH angle and 30 deg compound angles on the pressure and SS film-cooling holes. Nitrogen gas (cooling air) was fed through nozzle vanes, and measurements were conducted on the endwall surface between the two airfoils where no direct film cooling was applied. Six cooling mass flow ratios (MFRs, blowing ratios) were studied, and local (phantom) film effectiveness distributions were measured. Film effectiveness distributions were pitchwise averaged for comparison. Phantom cooling on the endwall by the SS film injections was found to be insignificant, but phantom cooling on the endwall by the pressure side (PS) airfoil film injections noticeably helped the endwall cooling (phantom cooling) and was a strong function of the MFR. It was concluded that reducing the SH angle and introducing a compound angle on the PS injections would enhance the endwall surface phantom cooling, particularly for a higher MFR.

Implementation of Vortex Generator and Ramp to Improve Film Cooling Effectiveness on Blade Endwall

2021 ◽  
Author(s):  
Sadam Hussain ◽  
Xin Yan
Keyword(s):  
Numerical Methods ◽  
Film Cooling ◽  
Vortex Generator ◽  
Leading Edge ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Baseline Case ◽  
Cooling Hole ◽  
Cooling Effects ◽  
Endwall Film Cooling

Abstract With the arrangements of vortex generators (VG) and ramp, film cooling effects on endwall near leading edge were numerically investigated at two blowing ratios (i.e. M = 0.5 and M = 1). To determine suitable numerical methods, mesh independency analysis and turbulence model selection were carried out based on the existing experimental data and LES results. With the numerical methods, flow fields near the leading edge were visualized to illustrate the influence of VG and ramp on coolant coverage on blade endwall. Film cooling effectiveness distributions on endwall and coolant trajectories near leading edge were compared among five different configurations with VG and ramp. The results show that the attachment of coolant on blade endwall is improved with the implement of VG between shaped-hole and leading edge. With the implementation of ramp on endwall between cooling hole and leading edge, the coolant spreads wider on endwall along pitchwise direction than the baseline case. With the implementation of VG and ramp, film cooling effect on endwall near leading edge is significantly improved as compared with the only ramp and only VG cases. Compared with the baseline case, pitchwise-averaged film cooling effectiveness on blade endwall near leading edge is increased by about 9%, and the film cooling effectiveness distributions on endwall along pitchwise direction become much uniform, for the case with both ramp and VG at M = 1.

Experimental Flow Visualization Study in a Trapezoidal Duct With Impingement Jets and Cross Flow Near the Leading Edge

2010 ◽  
Author(s):  
Haiyong Liu ◽  
Songling Liu ◽  
Hongfu Qiang ◽  
Cunliang Liu
Keyword(s):  
Film Cooling ◽  
Cross Flow ◽  
Side Wall ◽  
Leading Edge ◽  
Flow Fields ◽  
Flow Structures ◽  
Internal Cooling ◽  
Design And Optimization ◽  
Target Wall ◽  
Cooling Hole

An enlarged model of trapezoidal duct in leading-edge with impingement jets, swirl, cross flow and effusion was built up. Experiments were performed to measure flow fields in the confined passage and exit holes on one of its side walls. A row of staggered circular impingement holes were arranged on the opposite side wall. Cross flow and effusion flow was induced in the channel by the outflow of exit hole and film cooling hole, which were oriented on one end wall and bottom wall of the passage. Detailed flow structures were measured for two impingement angles of 35° and 45° with 6 combinations of out flow ratios. Results showed that the small jets impinged the target wall effectively while the large jets contributed to inducing and impelling a strong counter-clockwise vortex in the upper part of the passage. Cross flow had significant effect on the flow structures in the passage and exit holes. It deflected the jets, enhanced swirl and deteriorated side exit conditions. Impingement angle also had important influence on flow fields and its effect revealed more evidently with cross flow. Within the present test conditions, the mass flow rates and outflow positions of film cooling holes had no distinct effect on the main flow structures. These data were helpful for the design and optimization of internal cooling structures in gas turbine airfoils.

scholarly journals Reduction in Flow Parameter Resulting From Volcanic Ash Deposition in Engine Representative Cooling Passages

2016 ◽  
Author(s):  
Sebastien Wylie ◽  
Alexander Bucknell ◽  
Peter Forsyth ◽  
Matthew McGilvray ◽  
David R. H. Gillespie
Keyword(s):  
Film Cooling ◽  
Volcanic Ash ◽  
Flow Parameter ◽  
Cooling System ◽  
Pressure Ratio ◽  
Turbine Blades ◽  
Metal Temperature ◽  
Internal Cooling ◽  
Cooling Hole ◽  
Cooling Passage

Internal cooling passages of turbine blades have long been at risk to blockage through the deposition of sand and dust during fleet service life. The ingestion of high volumes of volcanic ash therefore poses a real risk to engine operability. An additional difficulty is that the cooling system is frequently impossible to inspect in order to assess the level of deposition. This paper reports results from experiments carried out at typical HP turbine blade metal temperatures (1163K to 1293K) and coolant inlet temperatures (800K to 900K) in engine scale models of a turbine cooling passage with film-cooling offtakes. Volcanic ash samples from the 2010 Eyjafjallajökull eruption were used for the majority of the experiments conducted. A further ash sample from the Chaiten eruption allowed the effect of changing ash chemical composition to be investigated. The experimental rig allows the metered delivery of volcanic ash through the coolant system at the start of a test. The key metric indicating blockage is the flow parameter which can be determined over a range of pressure ratios (1.01–1.06) before and after each experiment, with visual inspection used to determine the deposition location. Results from the experiments have determined the threshold metal temperature at which blockage occurs for the ash samples available, and characterise the reduction of flow parameter with changing particle size distribution, blade metal temperature, ash sample composition, film-cooling hole configuration and pressure ratio across the holes. There is qualitative evidence that hole geometry can be manipulated to decrease the likelihood of blockage. A discrete phase CFD model implemented in Fluent has allowed the trajectory of the ash particles within the coolant passages to be modelled, and these results are used to help explain the behaviour observed.

Experimental and Computational Investigation of Integrated Internal and Film Cooling Designs Incorporating a Thermal Barrier Coating

2021 ◽  
Author(s):  
Matthew J. Horner ◽  
Christopher Yoon ◽  
Michael Furgeson ◽  
Todd A. Oliver ◽  
David G. Bogard
Keyword(s):  
Film Cooling ◽  
Velocity Ratio ◽  
Thermal Barrier ◽  
Internal Cooling ◽  
Barrier Coating ◽  
Component Design ◽  
Turbine Component ◽  
Cooling Hole ◽  
Optimum Velocity ◽  
Overall Effectiveness

Abstract Few studies in the open literature have studied the effect of thermal barrier coatings when used in combination with shaped hole film cooling and enhanced internal cooling techniques. The current study presents RANS conjugate heat transfer simulations that identify trends in cooling design performance as well as experimental measurements of overall effectiveness using a flat-plate matched-Biot number model with a simulated TBC layer of 0.42D thickness, where D is the film cooling hole diameter. Coolant is fed to the film cooling holes in a co-flow configuration, and the results of both smooth and rib-turbulated channels are compared. At a constant coolant flow rate, enhanced internal cooling was found to provide a 44% increase in spatially-averaged overall effectiveness, ϕ ̿ , without a TBC. The results show that the addition of a TBC can raise ϕ ̿ on a film-cooled component surface by 47%. The optimum velocity ratio was found to decrease with the addition of enhanced cooling techniques and a TBC as the film provided minimal benefit at the expense of reduced internal cooling. While the computational results closely identified trends in overall system performance without a TBC, the model over-predicted effectiveness on the metal-TBC interface. The results of this study will inform turbine component design as material science advances increase the reliability of TBC.

An Experimental and Numerical Investigation of the Effect of Cooling Channel Crossflow on Film Cooling Performance

2007 ◽  
Author(s):  
Harald Peter Kissel ◽  
Bernhard Weigand ◽  
Jens von Wolfersdorf ◽  
Sven Olaf Neumann ◽  
Antje Ungewickell
Keyword(s):  
Numerical Investigation ◽  
Film Cooling ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Gas Channel ◽  
Cooling Hole ◽  
Flow Situation

This paper presents an experimental and numerical investigation into film cooling performance over a flat plate. As previous studies have shown, the flow situation at the entry-side of the cooling hole shows a notable effect on film cooling performance. The present investigation takes this into account feeding the cooling holes from an internal cooling channel and not from a stagnant plenum. High resolution heat transfer coefficient and adiabatic film cooling effectiveness distributions received from transient liquid crystal experiments are presented. The Reynolds numbers of the hot gas channel and the coolant crossflow feeding the holes are varied. Furthermore, the effects of 45° angled ribs, introduced into the cooling channel, are investigated. The experiments are performed at constant blowing, momentum and pressure ratios. Numerical calculations of the adiabatic film cooling effectiveness for selected configurations using FLUENT are presented. Comparison reveals the influence of coolant channel Reynolds number and the introduced ribs on the cooling hole flow pattern leading to a changed film cooling performance.

Sensitivity of the Overall Effectiveness to Film Cooling and Internal Cooling on a Turbine Vane Suction Side

2013 ◽  
Vol 136 (3) ◽  
Author(s):  
Randall P. Williams ◽  
Thomas E. Dyson ◽  
David G. Bogard ◽  
Sean D. Bradshaw
Keyword(s):  
Film Cooling ◽  
Momentum Flux ◽  
Suction Side ◽  
Coolant Temperature ◽  
Internal Cooling ◽  
Cooling Effectiveness ◽  
Impingement Cooling ◽  
Turbine Vane ◽  
Cooling Effects ◽  
Engine Components

The overall cooling effectiveness for a turbine airfoil was quantified based on the external surface temperature relative to the mainstream temperature and the inlet coolant temperature. This can be determined experimentally when the model is constructed so that the Biot number is similar to that of engine components. In this study, the overall cooling effectiveness was experimentally measured on a model turbine vane constructed of a material deigned to match Bi for engine conditions. The model incorporated an internal impingement cooling configuration. Overall cooling effectiveness and adiabatic film effectiveness were measured downstream of a single row of round holes positioned on the suction side of the vane. Experiments were conducted to evaluate the cooling effects of internal cooling alone, and then the combined effects of film cooling and internal cooling for a range of coolant flow rates. While the adiabatic film effectiveness decreased when using high momentum flux ratios for the film cooling, due to coolant jet separation, the overall cooling effectiveness increased at higher momentum flux ratios. This increase was due to increased internal cooling effects. Overall cooling effectiveness measurements were also compared to analytical predictions based on a 1D thermal analysis using measured adiabatic film effectiveness and overall cooling effectiveness without film cooling.

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