A Novel Transition-Sensitive Conjugate Methodology Applied to Turbine Vane Heat Transfer

2003 ◽  
Author(s):  
William D. York ◽  
D. Keith Walters ◽  
James H. Leylek
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Conjugate Heat Transfer ◽  
Operating Conditions ◽  
Boundary Layer Transition ◽  
Airfoil Surface ◽  
New Model ◽  
Numerical Predictions ◽  
Turbine Vane

A documented numerical methodology for conjugate heat transfer was employed to predict the metal temperature of an internally-cooled gas turbine vane at realistic operating conditions. The conjugate heat transfer approach involves the simultaneous solution of the flow field (convection) and the conduction within the metal vane, allowing a solution of the complete heat transfer problem in a single simulation. This technique means better accuracy and faster turn-around time than the typical industry practice of multiple, decoupled solutions. In the present simulations, the solid and fluid zones were coupled by energy conservation at the interfaces. In the fluid zones, the Reynoldsaveraged Navier-Stokes equations were closed with a three-equation, eddy-viscosity model, developed in-house and previously documented, with the capability to predict laminar-to-turbulent boundary-layer transition. The single-point model is fully-predictive for transition and requires no problem-dependent user inputs. For comparison, a simulation was also run with a commercially available Realizable k-ε turbulence model. A high-quality, unstructured gird was employed in both cases. Numerical predictions for midspan temperature on the airfoil surface are compared to data from an open-literature experiment with the same geometry and operating conditions. The new model captured transition of the initially laminar boundary layer to a turbulent boundary layer on the suction surface. The results with the new model show excellent agreement with measured data for surface temperature over the majority of the airfoil surface. The new model showed a marked improvement over the Realizable k-ε model in all regions where laminar boundary layers exist, highlighting the importance of accurately modeling transition in turbomachinery heat transfer simulations.

Modeling of Rough Wall Boundary Layer Transition and Heat Transfer on Turbine Airfoils

2006 ◽  
Author(s):  
M. Stripf ◽  
A. Schulz ◽  
H.-J. Bauer
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Boundary Layer Transition ◽  
Rough Wall ◽  
New Model ◽  
Free Stream Turbulence ◽  
Wall Boundary Layer ◽  
Wall Boundary ◽  
Turbine Airfoils

A new model for predicting heat transfer in the transitional boundary layer of rough turbine airfoils is presented. The new model makes use of extensive experimental work recently published by the current authors. For the computation of the turbulent boundary layer a discrete element roughness model is combined with a two-layer model of turbulence. The transition region is modeled using an intermittency equation that blends between the laminar and turbulent boundary layer. Several intermittency functions are evaluated in respect of their applicability to rough-wall transition. To predict the onset of transition a new correlation is presented, accounting for the influence of free-stream turbulence and surface roughness. Finally the new model is tested against transitional rough-wall boundary layer flows on high-pressure and low-pressure turbine airfoils.

Modeling of Rough-Wall Boundary Layer Transition and Heat Transfer on Turbine Airfoils

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
M. Stripf ◽  
A. Schulz ◽  
H.-J. Bauer
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Boundary Layer Transition ◽  
Rough Wall ◽  
Layer Transition ◽  
New Model ◽  
Wall Boundary Layer ◽  
Wall Boundary ◽  
Turbine Airfoils

A new model for predicting heat transfer in the transitional boundary layer of rough turbine airfoils is presented. The new model makes use of extensive experimental work recently published by the current authors. For the computation of the turbulent boundary layer, a discrete element roughness model is combined with a two-layer model of turbulence. The transition region is modeled using an intermittency equation that blends between the laminar and turbulent boundary layer. Several intermittency functions are evaluated in respect of their applicability to rough-wall transition. To predict the onset of transition, a new correlation is presented, accounting for the influence of freestream turbulence and surface roughness. Finally, the new model is tested against transitional rough-wall boundary layer flows on high-pressure and low-pressure turbine airfoils.

An Experimental Study of Heat Transfer on an Outlet Guide Vane

2014 ◽  
Author(s):  
Chenglong Wang ◽  
Lei Wang ◽  
Bengt Sundén ◽  
Valery Chernoray ◽  
Hans Abrahamsson
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Reynolds Number ◽  
Turbulent Boundary Layer ◽  
Guide Vane ◽  
Incidence Angle ◽  
Boundary Layer Transition ◽  
Transfer Coefficients ◽  
Suction Surface ◽  
Layer Transition

In the present study, the heat transfer characteristics on the suction and pressure sides of an outlet guide vane (OGV) are investigated by using liquid crystal thermography (LCT) method in a linear cascade. Because the OGV has a complex curved surface, it is necessary to calibrate the LCT by taking into account the effect of viewing angles of the camera. Based on the calibration results, heat transfer measurements of the OGV were conducted. Both on- and off-design conditions were tested, where the incidence angles of the OGV were 25 degrees and −25 degrees, respectively. The Reynolds numbers, based on the axial flow velocity and the chord length, were 300,000 and 450,000. In addition, heat transfer on suction side of the OGV with +40 degrees incidence angle was measured. The results indicate that the Reynolds number and incidence angle have considerable influences upon the heat transfer on both pressure and suction surfaces. For on-design conditions, laminar-turbulent boundary layer transitions are on both sides, but no flow separation occurs; on the contrary, for off-design conditions, the position of laminar-turbulent boundary layer transition is significantly displaced downstream on the suction surface, and a separation occurs from the leading edge on the pressure surface. As expected, larger Reynolds number gives higher heat transfer coefficients on both sides of the OGV.

Momentum and Thermal Boundary Layer Development on an Internally Cooled Turbine Vane

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Jason E. Dees ◽  
David G. Bogard ◽  
Gustavo A. Ledezma ◽  
Gregory M. Laskowski ◽  
Anil K. Tolpadi
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Thermal Boundary Layer ◽  
Conjugate Heat Transfer ◽  
Freestream Turbulence ◽  
Boundary Layer Development ◽  
Turbine Vane ◽  
Internally Cooled ◽  
Momentum Boundary Layer ◽  
Computational Predictions

Recent advances in computing power have made conjugate heat transfer simulations of turbine components increasingly popular; however, limited experimental data exist with which to evaluate these simulations. The primary parameter used to evaluate simulations is often the external surface temperature distribution, or overall effectiveness. In this paper, the overlying momentum and thermal boundary layers at various streamwise positions around a conducting, internally cooled simulated turbine vane were measured under low (Tu = 0.5%) and high (Tu = 20%) freestream turbulence conditions. Furthermore, experimental results were compared to computational predictions. In regions where a favorable pressure gradient existed, the thermal boundary layer was found to be significantly thicker than the accompanying momentum boundary layer. Elevated freestream turbulence had the effect of thickening the thermal boundary layer much more effectively than the momentum boundary layer over the entire vane. These data are valuable in understanding the conjugate heat transfer effects on the vane as well as serving as a tool for computational code evaluation.

Surface Roughness Effects on External Heat Transfer of a HP Turbine Vane

2005 ◽  
Vol 127 (1) ◽  
pp. 200-208 ◽  
Author(s):  
M. Stripf ◽  
A. Schulz ◽  
S. Wittig
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Surface Roughness ◽  
Turbulent Boundary Layer ◽  
Full Range ◽  
Reynolds Numbers ◽  
External Heat ◽  
Reference Surface ◽  
External Heat Transfer ◽  
Turbine Vane

External heat transfer measurements on a highly loaded turbine vane with varying surface roughness are presented. The investigation comprises nine different roughness configurations and a smooth reference surface. The rough surfaces consist of evenly spaced truncated cones with varying height, diameter, and distance, thus covering the full range of roughness Reynolds numbers in the transitionally and fully rough regimes. Measurements for each type of roughness are conducted at several freestream turbulence levels (Tu1=4% to 8.8%) and Reynolds numbers, hereby quantifying their combined effect on heat transfer and laminar-turbulent transition. In complementary studies a trip wire is used on the suction side in order to fix the transition location close to the stagnation point, thereby allowing a deeper insight into the effect of roughness on the turbulent boundary layer. The results presented show a strong influence of roughness on the onset of transition even for the smallest roughness Reynolds numbers. Heat transfer coefficients in the turbulent boundary layer are increased by up to 50% when compared to the smooth reference surface.

Effect of Surface Roughness on Conjugate Heat Transfer of a Turbine Vane

2016 ◽  
Author(s):  
Hongyang Li ◽  
Yun Zheng
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Surface Roughness ◽  
Suction Side ◽  
Transition Process ◽  
Considerable Effect ◽  
Boundary Layer Transition ◽  
Layer Transition ◽  
Turbine Vane ◽  
Effect Of Surface

For the purpose of researching the effect of surface roughness on boundary layer transition and heat transfer of turbine blade, a roughness modification approach for γ-Reθ transition model was proposed based on an in-house CFD code. Taking surface roughness effect into consideration, No. 5411 working condition of Mark II turbine vane was simulated and the results were analyzed in detail. Main conclusions are as follows: Surface roughness has little effect on heat transfer of laminar boundary layer, while has considerable effect on turbulent boundary layer. Compared with smooth surface, equivalent sand roughness of 100μm increases the temperature for about 28.4K on suction side, reaching an increase of 5%. Under low roughness degree, effect of shock wave dominants on boundary layer transition process on suction side, while above the critical degree, effect of surface roughness could abruptly change the transition point.

Conjugate heat transfer simulation of turbine blade high efficiency cooling method with mist injection

2014 ◽  
Vol 228 (15) ◽  
pp. 2738-2749 ◽  
Author(s):  
Yuting Jiang ◽  
Qun Zheng ◽  
Guoqiang Yue ◽  
Ping Dong ◽  
Jie Gao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Conjugate Heat Transfer ◽  
High Efficiency ◽  
Turbulence Models ◽  
Operating Conditions ◽  
Cooling Performance ◽  
Convective Cooling ◽  
Mist Cooling ◽  
The Impact

The idea of utilizing a finely dispersed water-in-air mixture has been proven to be a feasible technique to produce very high cooling rates. The accuracy of numerical simulation program for conjugate heat transfer methodology is verified with the Mark II transonic high pressure turbine stator which is cooled by internal convection through radial round pipes, and different turbulence models and transition models are employed to analyze the influence on results. On the basis of it, the mist cooling is simulated under typical gas turbine operating conditions for internal convective cooling to discuss the improvement of cooling performance. Though the results indicate that mist cooling can decrease the temperature of boundary layer without impact on the temperature of the mainstream and the thickness of boundary layer, the cooling capacity is limited by inadequate evaporation of mist. Considering the distribution of thermal stress and mist evaporation, a compound cooling blade of film cooling with trailing edge ejection is acquired which is modified from the blade of Mark II internal convective cooling; the effects of various parameters including mist concentration and mist diameter on the improvement of cooling performance are investigated, meanwhile the impact of curvature on cooling efficiency and mist trajectory is analyzed finally.

Large Eddy Simulation of a Transonic Linear Cascade With Synthetic Inlet Turbulence

2020 ◽  
Author(s):  
Ettore Bertolini ◽  
Paul Pieringer ◽  
Wolfgang Sanz
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Fluid Dynamic ◽  
Operating Conditions ◽  
Boundary Layer Transition ◽  
Turbine Cascade ◽  
Layer Transition ◽  
Free Stream Turbulence ◽  
Turbulence Decay ◽  
Large Eddy

Abstract The aim of this work is to predict the boundary layer transition and the heat transfer on a highly loaded transonic turbine cascade using Large Eddy Simulations (LESs) with prescribed inlet synthetic turbulence. The numerical simulations were performed for the flow in a linear turbine cascade tested at the von Karman Institute for Fluid Dynamic (MUR test case). For the numerical case, two operating conditions with two different levels of free-stream turbulence intensity are evaluated. For the lower turbulence level case (Tu = 0.8%, MUR132) a laminar inflow is used for the LES simulations whereas for the higher one (Tu = 6%, MUR237) the inlet turbulence is prescribed by using the Synthetic Eddy Method (SEM) of Jarrin. The first part of this work deals with the LES setup. The standard Smagorinsky model was used as closure model. A value of the Smagorinsky constant CS = 0.05 was chosen whereas the turbulent viscosity was reduced in the region closest to the wall by changing the definition of the Smagorinsky length scale. To handle the strong fluctuations in the flow field the cell fluxes are computed using the WENO-P scheme. In the second part, precursor RANS and LES simulations are used to set the optimal values of the SEM parameters and to guarantee the correct level of turbulence at the blade leading edge. The turbulence decay of the synthetic turbulence is compared with the one of the RANS κ–ωSST model. Finally, a comparison between experimental and numerical results is done and the ability of LES to predict the boundary layer transition and the heat transfer on the blade surface is evaluated for the two different inflow conditions.

Overall and Adiabatic Effectiveness Values on a Scaled Up, Simulated Gas Turbine Vane

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Jason E. Dees ◽  
David G. Bogard ◽  
Gustavo A. Ledezma ◽  
Gregory M. Laskowski
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Gas Turbine ◽  
Film Cooling ◽  
Conjugate Heat Transfer ◽  
Flux Ratio ◽  
Boundary Layer Transition ◽  
Data Set ◽  
Turbine Vane ◽  
Adiabatic Effectiveness

Recent advances in computational power have made conjugate heat transfer simulations of fully conducting, film cooled turbine components feasible. However, experimental data available with which to validate conjugate heat transfer simulations is limited. This paper presents experimental measurements of external surface temperature on the suction side of a scaled up, fully conducting, cooled gas turbine vane. The experimental model utilizes the matched Bi method, which produces nondimensional surface temperature measurements that are representative of engine conditions. Adiabatic effectiveness values were measured on an identical near adiabatic vane with an identical geometry and cooling configuration. In addition to providing a valuable data set for computational code validation, the data shows the effect of film cooling on the surface temperature of a film cooled part. As expected, in nearly all instances, the addition of film cooling was seen to decrease the overall surface temperature. However, due to the effect of film injection causing early boundary layer transition, film cooling at a high momentum flux ratio was shown to actually increase surface temperature over 0.35 < s/C < 0.45.

Overall and Adiabatic Effectiveness Values on a Scaled Up, Simulated Gas Turbine Vane: Part I—Experimental Measurements

2011 ◽  
Author(s):  
Jason E. Dees ◽  
David G. Bogard ◽  
Gustavo A. Ledezma ◽  
Gregory M. Laskowski
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Gas Turbine ◽  
Film Cooling ◽  
Conjugate Heat Transfer ◽  
Boundary Layer Transition ◽  
Experimental Measurements ◽  
Data Set ◽  
Turbine Vane ◽  
Adiabatic Effectiveness

Recent advances in computational power have made conjugate heat transfer simulations of fully conducting, film cooled turbine components feasible. However, experimental data available with which to validate conjugate heat transfer simulations is limited. This paper presents experimental measurements of external surface temperature on the suction side of a scaled up, fully conducting, cooled gas turbine vane. The experimental model utilizes the matched Bi method, which produces non-dimensional surface temperature measurements that are representative of engine conditions. Adiabatic effectiveness values were measured on an identical near adiabatic vane with an identical geometry and cooling configuration. In addition to providing a valuable data set for computational code validation, the data shows the effect of film cooling on the surface temperature of a film cooled part. As expected, in nearly all instances the addition of film cooling was seen to decrease the overall surface temperature. However, due to the effect of film injection causing early boundary layer transition, film cooling at a high momentum flux ratio was shown to actually increase surface temperature over 0.35 < s/C < 0.45.

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