Effective Radiation Modelling Technique for Transient Temperature Prediction of Gas Turbine Components

2012 ◽  
Author(s):  
S. Y. Suresh Cherukupalli ◽  
Krishna Nelanti ◽  
Kamlesh G. Gujar ◽  
John Sunil Palle
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Shape Factor ◽  
Surface Effect ◽  
New Technique ◽  
Computational Time ◽  
Transient Temperature ◽  
Time Accuracy ◽  
Radiation Modeling ◽  
Element Method

Gas Turbine engine components like Combustor, Diffuser, and Turbines are subjected to very high temperatures. Predicting accurate temperatures of such components demand accurate Radiation modeling along with Conduction and Convection. Radiation heat transfer modeling is very complex due to non linear dependence on temperature and additional parameters driving the heat transfer like shape factor, emissivity, surface area and absorbtivity of material. The commercial software ANSYS developed various Radiation techniques like ‘Radiation Matrix’, ‘Radiosity’ and ‘Radiation modeling between a surface and a point’. A detailed study has been carried out to compare different Radiation models. The ease of building the model, computational time, accuracy, and limitations are thoroughly examined. It is found that all existing methods have some limitations in accuracy, computational time or system requirements. To overcome some of these limitations, a new technique called ‘Surface Effect Element Method’ is proposed in this paper. This method uses ‘Radiosity’ for the shape factor computation and ‘Radiation modeling between a surface and a point’ for modeling Radiation between two surfaces. The average of one surface temperature is transferred to a single point which in turn is used to model the Radiation to the second surface and the same procedure is repeated for the second surface too. A detailed study is carried out and the proposed technique is compared against the available methods. The new technique enables accurate computation of transient temperatures for gas turbine components leading to accurate life prediction for these components. It is shown that ‘Surface Effect Element Method’ has comparable accuracy but significantly lower cycle time and efforts compared to existing methods.

Large-Eddy Simulation of Flow and Convective Heat Transfer in a Gas Turbine Can Combustor With Synthetic Inlet Turbulence

2012 ◽  
Vol 134 (7) ◽  
Author(s):  
Sunil Patil ◽  
Danesh Tafti
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Convective Heat Transfer ◽  
Gas Turbine ◽  
Convective Heat ◽  
Computational Time ◽  
Computational Domain ◽  
Rans Simulation ◽  
Eddy Simulation ◽  
Large Eddy

Large eddy simulations of swirling flow and the associated convective heat transfer in a gas turbine can combustor under cold flow conditions for Reynolds numbers of 50,000 and 80,000 with a characteristic Swirl number of 0.7 are carried out. A precursor Reynolds averaged Navier-Stokes (RANS) simulation is used to provide the inlet boundary conditions to the large-eddy simulation (LES) computational domain, which includes only the can combustor. A stochastic procedure based on the classical view of turbulence as a superposition of the coherent structures is used to simulate the turbulence at the inlet plane of the computational domain using the mean flow velocity and Reynolds stress data from the precursor RANS simulation. To further reduce the overall computational resource requirement and the total computational time, the near wall region is modeled using a zonal two layer model (WMLES). A novel formulation in the generalized co-ordinate system is used for the solution of effective tangential velocity and temperature in the inner layer virtual mesh. The WMLES predictions are compared with the experimental data of Patil et al. (2011, “Experimental and Numerical Investigation of Convective Heat Transfer in Gas Turbine Can Combustor,” ASME J. Turbomach., 133(1), p. 011028) for the local heat transfer distribution on the combustor liner wall obtained using robust infrared thermography technique. The heat transfer coefficient distribution on the liner wall predicted from the WMLES is in good agreement with experimental values. The location and the magnitude of the peak heat transfer are predicted in very close agreement with the experiments.

Predicting Skin Friction and Heat Transfer for Turbulent Flow Over Real Gas-Turbine Surface Roughness Using the Discrete-Element Method

2003 ◽  
Author(s):  
Stephen T. McClain ◽  
B. Keith Hodge ◽  
Jeffrey P. Bons
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Wind Tunnel ◽  
Discrete Element Method ◽  
Skin Friction ◽  
Gas Turbine ◽  
Discrete Element ◽  
Real Gas ◽  
Roughness Elements ◽  
Element Method

The discrete-element method considers the total aerodynamic drag on a rough surface to be the sum of shear drag on the flat part of the surface and the form drag on the individual roughness elements. The total heat transfer from a rough surface is the sum of convection through the fluid on the flat part of the surface and the convection from each of the roughness elements. The discrete-element method has been widely used and validated for predicting heat transfer and skin friction for rough surfaces composed of sparse, ordered, and deterministic elements. Real gas-turbine surface roughness is different from surfaces with sparse, ordered, and deterministic roughness elements. Modifications made to the discrete-element roughness method to extend the validation to real gas-turbine surface roughness are detailed. Two rough surfaces found on high-hour gas-turbine blades were characterized using a Taylor-Hobson Form Talysurf Series 2 profilometer. Two rough surfaces and two elliptical-analog surfaces were generated for wind-tunnel testing using a three-dimensional printer. The printed surfaces were scaled to maintain similar boundary-layer thickness to roughness height ratio in the wind tunnel as found in gas-turbine operation. The results of the wind tunnel skin friction and Stanton number measurements and the discrete-element method predictions for each of the four surfaces are presented and discussed. The discrete-element predictions made considering the gas-turbine roughness modifications are within 7% of the experimentally-measured skin friction coefficients and are within 16% of the experimentally-measured Stanton numbers.

Determination of Non-Uniform Heat Transfer Coefficients Around a Solid Aluminum Alloy Complex Shape During Quenching by Using an Inverse Method

2002 ◽  
Author(s):  
Pen-Chung Chen ◽  
Deborah A. Kaminski ◽  
Robert W. Messler
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Inverse Method ◽  
Flux Measurement ◽  
Transient Temperature ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Uniform Heat ◽  
The Cost ◽  
Transfer Problems

Gas turbine systems include complex heat transfer problems. Especially, the cooling efficiency is critical to the operation of gas turbine. In order to achieve the desired cooling condition, one needs to know the distribution of heat transfer on the components; however, the cost to implement a full-scale gas turbine test is tremendous. Therefore, many researchers used simplified models to acquire the test data; certain experiments can provide heat flux measurement, whereas other techniques can measure heat transfer coefficients. The direct measurement of heat transfer coefficients on the surface of components is extremely difficult. In such situations, the inverse method using transient temperature measurements taken within the part can be used to determine heat transfer coefficients. By combining experiments and numerical modeling, this presentation attempts to provide an effective and robust method to determine heat transfer coefficients on the part’s surface during cooling. Though the setting of the present paper is the quenching of a part, the technique presented is proposed for in-service heat load. To characterize the present situation, i.e., non-uniform heat transfer coefficients occurring during quenching, a unique methodology for employing inverse heat conduction was developed to obtain heat transfer coefficients from temperature responses. In conventional inverse approaches, the heat transfer coefficient is assumed to be uniform around the periphery, but this approach sometimes is unrealistic, especially for complex shaped parts. In this study, experimental data were used to find parameters in a heat transfer correlation, rather than to determine the coefficients directly. The resulting analysis provided an improved fit to measurements compared to conventional inverse approaches. The method developed was robust and is extendable to parts of arbitrary shape.

scholarly journals Inverse Heat Transfer Engineering Design for Internally Cooled Gas Turbine Airfoils

1996 ◽  
Author(s):  
Francisco J. T. Cunha ◽  
David A. DeAngelis
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Design Procedure ◽  
Combined Cycle ◽  
Gas Temperature ◽  
Transfer Coefficients ◽  
Inverse Heat Transfer ◽  
Component Design ◽  
Optimization Methodology ◽  
Element Method

In the design and development of modern gas turbine machines for efficient power generation in combined cycle applications, nozzle segments with airfoils and sidewalls need to be effectively cooled to operate in gas temperature environments in the excess of the melting point of the material of construction. Particular attention is given to the thermal evaluation as it affects component design life and performance. In this context, an optimization methodology is prescribed for inverse determination of required coolant heat transfer as a function of hot gas conditions and subjected to constraints associated with allowable metal temperature. A general boundary element method is used in the optimization process to provide a relatively fast and economically feasible design procedure. The optimized set of heat transfer results are converged when the external metal temperatures fall within acceptable limits. Once the magnitude and distribution of required coolant heat transfer coefficients are obtained, the cooling technique can be devised using available or referenced correlations for impingement jets through insert plates, banks of pin fins, turbulators, or just simply forced convection through internal passages. An illustrative example is presented with a Joukowski airfoil using a finite element method as an alternative method of solution for comparison and verification.

Numerical Integral Independent of Frequency in the Boundary Element Method for Acoustic Scattering

2013 ◽  
Vol 444-445 ◽  
pp. 650-654
Author(s):  
Zai You Yan ◽  
Chuan Zhen Li
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Acoustic Scattering ◽  
Normal Derivative ◽  
Numerical Results ◽  
New Technique ◽  
Computational Time ◽  
Unknown Variable ◽  
Numerical Integral ◽  
Element Method

Fast algorithm for multi-frequency numerical integration in the simulation of acoustic scattering from rigid object by the boundary element method is presented. Normal derivative of the free-space Greens function is partially approximated with the unknown variable by a set of shape functions. As a result, the numerical integral is independent of frequency and need be calculated only at the first frequency step. Singular integral can be computed using the same procedure as that applied in the conventional boundary element method. Computational efficiency and accuracy of the new technique are demonstrated by an example. Numerical results obtained using the new technique are compared with the corresponding analytical solutions and numerical results obtained using the conventional boundary element method. The new technique works well and saves a lot of computational time in the process of generation of coefficient matrices for multi-frequency analysis.

Large Eddy Simulation of Flow and Convective Heat Transfer in a Gas Turbine Can Combustor With Synthetic Inlet Turbulence

2011 ◽  
Author(s):  
Sunil Patil ◽  
Danesh Tafti
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Convective Heat Transfer ◽  
Gas Turbine ◽  
Convective Heat ◽  
Computational Time ◽  
Computational Domain ◽  
Rans Simulation ◽  
Eddy Simulation ◽  
Large Eddy

Large eddy simulations of swirling flow and the associated convective heat transfer in a gas turbine can combustor under cold flow conditions for Reynolds numbers of 50,000 and 80,000 with characteristic Swirl number of 0.7 are carried out. A precursor Reynolds Averaged Navier-Stokes (RANS) simulation is used to provide the inlet boundary conditions to the large-eddy simulation (LES) computational domain, which includes only the can combustor. A stochastic procedure based on the classical view of the turbulence as superposition of the coherent structures is used to simulate the turbulence at the inlet plane of the computational domain using the mean flow velocity and Reynolds stress data from the precursor RANS simulation. To further reduce the overall computational resource requirement and the total computational time, the near wall region is modeled using zonal two layer model. A novel formulation in generalized co-ordinate system is used for solution of effective tangential velocity and temperature in the inner layer virtual mesh. LES predictions are compared with the experimental data of Patil et al. [1] for the local heat transfer distribution on the combustor liner wall obtained using robust infrared thermography technique. The heat transfer coefficient distribution on the liner wall predicted from LES is in good agreement with experimental values. The location and the magnitude of the peak heat transfer are predicted in very close agreement with the experiments.

Predicting Skin Friction and Heat Transfer for Turbulent Flow Over Real Gas Turbine Surface Roughness Using the Discrete Element Method

2004 ◽  
Vol 126 (2) ◽  
pp. 259-267 ◽  
Author(s):  
Stephen T. McClain ◽  
B. Keith Hodge ◽  
Jeffrey P. Bons
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Wind Tunnel ◽  
Discrete Element Method ◽  
Skin Friction ◽  
Gas Turbine ◽  
Discrete Element ◽  
Real Gas ◽  
Roughness Elements ◽  
Element Method

The discrete element method considers the total aerodynamic drag on a rough surface to be the sum of shear drag on the flat part of the surface and the form drag on the individual roughness elements. The total heat transfer from a rough surface is the sum of convection through the fluid on the flat part of the surface and the convection from each of the roughness elements. The discrete element method has been widely used and validated for predicting heat transfer and skin friction for rough surfaces composed of sparse, ordered, and deterministic elements. Real gas turbine surface roughness is different from surfaces with sparse, ordered, and deterministic roughness elements. Modifications made to the discrete element roughness method to extend the validation to real gas turbine surface roughness are detailed. Two rough surfaces found on high-hour gas turbine blades were characterized using a Taylor-Hobson Form Talysurf Series 2 profilometer. Two rough surfaces and two elliptical-analog surfaces were generated for wind tunnel testing using a three-dimensional printer. The printed surfaces were scaled to maintain similar boundary layer thickness to roughness height ratio in the wind tunnel as found in gas turbine operation. The results of the wind tunnel skin friction and Stanton number measurements and the discrete element method predictions for each of the four surfaces are presented and discussed. The discrete element predictions made considering the gas turbine roughness modifications are within 7% of the experimentally measured skin friction coefficients and are within 16% of the experimentally measured Stanton numbers.

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