scholarly journals A Comparison of Experimental and Computational Heat Transfer Results for a Leading Edge Impingement System

2018 ◽  
Vol 3 (4) ◽  
pp. 23
Author(s):  
Robert Pearce ◽  
Peter Ireland ◽  
Ed Dane ◽  
Janendra Telisinghe
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Turbine Blades ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
High Heat ◽  
Navier Stokes ◽  
Spatially Resolved ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

Leading edge impingement systems are increasingly being used for high pressure turbine blades in gas turbine engines, in regions where very high heat loads are encountered. The flow structure in such systems can be very complex and high resolution experimental data is required for engine-realistic systems to enable code validation and optimal design. This paper presents spatially resolved heat transfer distributions for an engine-realistic impingement system for multiple different hole geometries, with jet Reynolds numbers in the range of 13,000–22,000. Following this, Reynolds-averaged Navier-Stokes computational fluid dynamics simulations are compared to the experimental data. The experimental results show variation in heat transfer distributions for different geometries, however average levels are primarily dependent on jet Reynolds number. The computational simulations match the shape of the distributions well however with a consistent over-prediction of around 10% in heat transfer levels.

Heat Transfer in Film-Cooled Turbine Blades

1993 ◽  
Author(s):  
Vijay K. Garg ◽  
Raymond E. Gaugler
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Film Cooling ◽  
Stokes Equations ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Explicit Finite Difference ◽  
Control Volumes

In order to study the effect of film cooling on the flow and heat transfer characteristics of actual turbine blades, a three-dimensional Navier-Stokes code has been developed. An existing code (Chima and Yokota, 1990) has been modified for the purpose. The code is an explicit finite difference code with an algebraic turbulence model. The thin-layer Navier-Stokes equations are solved using a general body-fitted coordinate system. The effects of film cooling have been incorporated into the code in the form of appropriate boundary conditions at the hole locations on the blade surface. Each hole exit is represented by several control volumes, thus providing an ability to study the effect of hole shape on the film-cooling characteristics. Comparison with experimental data is fair. Further validation of the code is required, however, and in this respect, there is an urgent need for detailed experimental data on actual turbine blades.

Transition Modeling Effects on Turbine Rotor Blade Heat Transfer Predictions

1996 ◽  
Vol 118 (2) ◽  
pp. 307-313 ◽  
Author(s):  
A. A. Ameri ◽  
A. Arnone
Keyword(s):  
Heat Transfer ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Turbine Rotor ◽  
Algebraic Model ◽  
Navier Stokes ◽  
Turbine Rotor Blade ◽  
Transition Length ◽  
Transition Modeling

The effect of transition modeling on the heat transfer predictions from rotating turbine blades was investigated. Three-dimensional computations using a Reynolds-averaged Navier–Stokes code were performed. The code utilized the Baldwin–Lomax algebraic turbulence model, which was supplemented with a simple algebraic model for transition. The heat transfer results obtained on the blade surface and the hub endwall were compared with experimental data for two Reynolds numbers and their corresponding rotational speeds. The prediction of heat transfer on the blade surfaces was found to improve with the inclusion of the transition length model and wake-induced transition effects over the simple abrupt transition model.

scholarly journals Predictions for the Effects of Freestream Turbulence on Turbine Blade Heat Transfer

2004 ◽  
Author(s):  
R. J. Boyle ◽  
Forrest E. Ames ◽  
P. W. Giel
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Steady State ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Freestream Turbulence ◽  
Suction Surface ◽  
Pressure Surface ◽  
Wide Range

An approach to predicting the effects of freestream turbulence on turbine vane and blade heat transfer is described. Four models for predicting the effects of freestream turbulence were incorporated into a Navier-Stokes CFD analysis. Predictions were compared with experimental data in order to identify an appropriate model for use across a wide range of flow conditions. The analyses were compared with data from five vane geometries and from four rotor geometries. Each of these nine geometries had data for different Reynolds numbers. Comparisons were made for twenty four cases. Steady state calculations were done because all experimental data were obtained in steady state tests. High turbulence levels often result in suction surface transition upstream of the throat, while at low to moderate Reynolds numbers the pressure surface remains laminar. A two-dimensional analysis was used because the flow is predominantly two-dimensional in the regions where freestream turbulence significantly augments surface heat transfer. Because the evaluation of models for predicting turbulence effects can be affected by other factors, the paper discusses modeling for transition, relaminarization, and near wall damping. Quantitative comparisons are given between the predictions and data.

Design and Experimental Studies of Turbine Cooling

1974 ◽  
Author(s):  
Tsuyoshi Hiroki ◽  
Ichiro Katsumata
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Film Cooling ◽  
Turbine Blades ◽  
Experimental Studies ◽  
Leading Edge ◽  
Air Cooling ◽  
Turbine Cooling ◽  
Aerodynamic Performances ◽  
Cooling Effects

Several problem areas associated with air-cooling of small turbine blades and vanes are identified. These problem areas include the leading edge cooling by film and impingement cooling, comparison of several configurations for trailing edge cooling, effects of Mach number on blade surface heat transfer, effects of film cooling on the aerodynamic performances of turbine cascades, the method of data correlation for the application of heat transfer data taken with low temperature, low pressure rig tests to high temperature, high pressure conditions. Experimental data are presented for each discussed area. The description of design and experimental data of one of the experimental cooled blades and vanes are presented.

Effects of 3-D Local Unsteadiness on Heat Transfer Prediction in Turbulated Passages

2003 ◽  
Author(s):  
Pamela A. McDowell ◽  
William D. York ◽  
D. Keith Walters ◽  
James H. Leylek
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Turbulence Model ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Successful Outcome ◽  
Small Scale ◽  
Cross Sectional ◽  
Fully Implicit

A newly developed unsteady turbulence model was used to predict heat transfer in a turbulated passage typical of turbine airfoil cooling applications. Comparison of fullyconverged computational solutions to experimental measurements reveal that accurate prediction of heat transfer coefficient requires the effects of local small-scale unsteadiness to be captured. Validation was accomplished through comparison of the time- and area-averaged Nusselt number on the passage wall between adjacent ribs with experimental data from the open literature. The straight channel had a square cross-sectional area with multiple rows of staggered and rounded-edge ribs on opposite walls that were orthogonal to the flow. Simulations were run for Reynolds numbers of 5500, 16500, and 25000. Computational solutions were obtained on a multi-block, multi-topology, unstructured, and adaptive grid, using a pressure-correction based, fully-implicit Navier-Stokes solver. The computational results include two-dimensional (2-D) and three-dimensional (3-D) steady and unsteady simulations with viscous sublayers resolved (y+ ≤ 1) on all the walls in every case. Turbulence closure was obtained using a new turbulence model developed in-house for the unsteady simulations, and a realizable k-ε turbulence model was used for the steady simulations. The results obtained from the unsteady simulations show greatly improved agreement with the experimental data, especially at realistically high Reynolds numbers. The key 3-D physics mechanisms responsible for the successful outcome include: (1) shear layer roll-up over the turbulators; (2) recirculation zones both upstream and downstream of the rib faces; and (3) reattachment regions between each rib pair. Results from the unsteady case are superior to those of the steady because they capture the aforementioned mechanisms, and therefore more accurately predict the heat transfer.

scholarly journals Transition Modeling Effects on Turbine Rotor Blade Heat Transfer Predictions

1994 ◽  
Author(s):  
Ali A. Ameri ◽  
Andrea Arnone
Keyword(s):  
Heat Transfer ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Turbine Rotor ◽  
Algebraic Model ◽  
Navier Stokes ◽  
Turbine Rotor Blade ◽  
Transition Length ◽  
Transition Modeling

The effect of transition modeling on the heat transfer predictions from rotating turbine blades was investigated. Three-dimensional computations using a Reynolds-averaged Navier-Stokes code were performed. The code utilized the Baldwin-Lomax algebraic turbulence model which was supplemented with a simple algebraic model for transition. The heat transfer results obtained on the blade surface and the hub end wall were compared with experimental data for two Reynolds numbers and their corresponding rotational speeds. The prediction of heat transfer on the blade surfaces was found to improve with the inclusion of the transition length model and wake induced transition effects over the simple abrupt transition model.

Combined Effects of Jet Plate Thickness and Fillet Radius on Leading Edge Jet Impingement With Round and Racetrack Shaped Jets

2015 ◽  
Author(s):  
Weston V. Harmon ◽  
Lesley M. Wright ◽  
Daniel C. Crites ◽  
Mark C. Morris ◽  
Ardeshir Riahi
Keyword(s):  
Heat Transfer ◽  
Turbine Blades ◽  
Plate Thickness ◽  
Leading Edge ◽  
Jet Impingement ◽  
Target Surface ◽  
Reynolds Numbers ◽  
Stagnation Region ◽  
Vena Contracta ◽  
Nusselt Numbers

The effect of jet plate thickness is considered as regionally averaged Nusselt numbers are measured on a concave surface, which models the leading edge of modern gas turbine blades. The performance of both round and racetrack shaped orifices for leading edge impingement is considered. Regionally averaged heat transfer coefficient distributions are obtained in a steady state experiment using heated aluminum plates. From this traditional heat transfer technique, the heat transfer afforded by jet plates of varying thickness is quantified. The thickness of the jet plate is varied from 1.33 to 4.0 diameters (for both the round and racetrack shaped jets). To model the modern, cast airfoil, the effect of an inlet and outlet radius on the jet orifice is also investigated. For all cases, the jet – to – target surface spacing (z/djet) is 4, the jet – to – jet spacing (s/djet) is 8, and the target surface diameter – to jet diameter (D/djet) is 5.33. Target surface Nusselt numbers are obtained for three separate Reynolds numbers. For the round orifices, jet Reynolds numbers of 14,000, 28,100, and 42,100 are used while the corresponding Reynolds numbers for the racetrack shaped jets are 11,800, 23,600, and 35,400. Although the Reynolds number is reduced for the racetrack shaped jets, the mass flow through each jet remains constant (from the round to the racetrack jets). The Nusselt numbers measured in the stagnation region of the target surface are relatively insensitive to the jet plate thickness. For all cases considered, the flow is not developed as it exits the orifice, so the flow structures of the jets ensuing from each of the plates are similar. When the inlet of the jet is rounded, the vena contracta effect within the orifice is minimized, and a more symmetrical jet develops within the orifice. For a fixed flow rate, the racetrack shaped jets provide enhanced heat transfer compared to the round jets for all geometries considered.

Numerical Prediction of Film Cooling and Heat Transfer on the Leading Edge of a Rotating Blade in a 1-1/2 Turbine Stage

2004 ◽  
Author(s):  
Huitao Yang ◽  
Hamn-Ching Chen ◽  
Je-Chin Han ◽  
Hee-Koo Moon
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Leading Edge ◽  
High Heat ◽  
Turbine Stage ◽  
Film Cooling Effectiveness ◽  
Rotating Blade ◽  
High Heat Transfer

In modern gas turbines, the blade leading edge region is one area that experiences high heat transfer due to the stagnation flow. Many cooling techniques have been applied to blades, so they can withstand these high heat loads; one of the common methods in cooling turbine blades is to apply film cooling. In the present study, numerical simulations were performed to predict the film cooling effectiveness and heat transfer coefficient on the leading edge of a rotating blade in a 1-1/2 turbine stage using a Reynolds stress turbulence model together with a non-equilibrium wall function. In addition, the unsteady characteristics of the film cooling and heat transfer at different time phases during a passing period were also investigated.

scholarly journals Navier–Stokes Analysis of Turbine Blade Heat Transfer

1991 ◽  
Vol 113 (3) ◽  
pp. 392-403 ◽  
Author(s):  
R. J. Boyle
Keyword(s):  
Heat Transfer ◽  
Free Stream ◽  
Three Dimensional ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Free Stream Turbulence ◽  
Eddy Viscosity Model ◽  
Experimental Heat ◽  
Experimental Heat Transfer

Comparisons with experimental heat transfer and surface pressures were made for seven turbine vane and blade geometries using a quasi-three-dimensional thin-layer Navier–Stokes analysis. Comparisons are made for cases with both separated and unseparated flow over a range of Reynolds numbers and free-stream turbulence intensities. The analysis used a modified Baldwin-Lomax turbulent eddy viscosity model. Modifications were made to account for the effects of: (1) free-stream turbulence on both transition and leading edge heat transfer; (2) strong favorable pressure gradients on relaminarizations; and (3) variable turbulent Prandtl number on heat transfer. In addition, the effect on heat transfer of the near-wall model of Deissler is compared with the Van Driest model.

Leading Edge Impingement With Racetrack Shaped Jets and Varying Inlet Supply Conditions

2013 ◽  
Author(s):  
C. Neil Jordan ◽  
Cassius A. Elston ◽  
Lesley M. Wright ◽  
Daniel C. Crites
Keyword(s):  
Heat Transfer ◽  
Test Section ◽  
Turbine Blades ◽  
Leading Edge ◽  
Target Surface ◽  
Reynolds Numbers ◽  
Impinging Jets ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Crossflow Velocity

Impinging jets are often employed within the leading edge of turbine blades and vanes to combat the tremendous heat loads incurred as the hot exhaust gases stagnate along the exterior of the airfoil. Relative to traditional cylindrical jets, racetrack shaped impinging jets have been shown to produce favorable cooling characteristics within the turbine airfoil. This investigation experimentally and numerically quantifies the cooling characteristics associated with a row of racetrack shaped jets impinging on a concave, cylindrical surface. Detailed Nusselt number distributions are obtained using both a transient liquid crystal technique and commercially available CFD software (Star CCM+ from CD-Adapco). Three geometrical jet inlet and exit conditions are experimentally investigated: a square edge, a partially filleted edge (r/dH,Jet = 0.25), and a fully filleted edge (r/dH,Jet = 0.667). Additionally, to investigate the effect of high crossflow velocities at the inlet of the jet, a portion of the flow supplied to the test apparatus radially bypasses the impingement section. Thus, the mass flow rate into the test section is varied to achieve the desired inlet crossflow conditions and jet Reynolds numbers. As a result, jet Reynolds numbers (ReJet) of 11500 and 23000 are investigated at supply duct Reynolds numbers (ReDuct) of 20000 and 30000. The results are compared to baseline cases where no mass bypasses the test section. Additionally, the relative jet – to – jet spacing (s/dH,Jet) is maintained at 8, the relative jet – to – target surface spacing (z/dH,Jet) is 4, the target surface curvature – to – jet hydraulic diameter (D/dH,Jet) is 5.33, and the relative thickness of the jet plate (t/dH,Jet) is 1.33. Measurements indicate that the addition of fillets at the edges of the jet orifice and the introduction of significant crossflow velocity at the inlet of the jet can significantly degrade the cooling characteristics on the leading edge of the turbine blade. The magnitude of such degradation generally increases with increasing fillet size and inlet crossflow velocity. The V2F model is adequate for predicting the flow field and target surface heat transfer in the absence of inlet crossflow; however, it is believed the turbulence within the jet is overpredicted by the CFD leading to elevated heat transfer coefficients (compared to the experimental results).

Sign in / Sign up

Export Citation Format

Share Document