Transfer Function Based Optimization of Film Hole Sizes With Conjugate Heat Transfer Analysis

2020 ◽  
Author(s):  
Sandip Dutta ◽  
Reid Smith
Keyword(s):  
Heat Transfer ◽  
Transfer Function ◽  
Transfer Functions ◽  
Optimization Technique ◽  
Leading Edge ◽  
Optimization Procedure ◽  
Metal Temperature ◽  
Heat Transfer Analysis ◽  
Maximum Temperature ◽  
Transfer Coefficients

Abstract With the improvements of 3D metal printing of turbine components, it is now feasible to produce ready to use production quality parts without casting and conventional machining. This new manufacturing technique has opened new frontiers in cooling optimizations that could not be practiced before. For example, it is now or in-the-near-future possible to have unconventional diameters of film holes. This paper seeks to optimize each film hole diameter at the leading edge of a turbine to achieve an optimum thermal objective. The design technique developed uses a transfer function-based learning model and can be used for both stationary and rotating airfoils. Proposed optimization procedure will also work on other parts of an airfoil; but our current analysis is limited to the leading-edge region. To apply this work on other critical regions, the corresponding heat transfer coefficients need to be implemented while building the transfer functions suitable for that specific component; however, the underlying optimization technique stays the same for any other component. Any optimization technique needs cost and benefit criteria. Cost is minimized in optimization to get maximum benefit with given constraints. In gas-turbine heat transfer, there is a ceiling constraint on maximum temperature that must be satisfied. This study minimizes the coolant flow with satisfying the constraints on average metal temperature and metal temperature variations that limit the life of turbine components. Proposed methodology provides a scientific basis for the sizing of film holes and is expected to decrease developmental cost of efficient thermal designs.

scholarly journals Shape optimization of turbine blades with the integration of aerodynamics and heat transfer

1998 ◽  
Vol 4 (1) ◽  
pp. 21-42 ◽  
Author(s):  
J. N. Rajadas ◽  
A. Chattopadhyay ◽  
N. Pagaldipti ◽  
S. Zhang
Keyword(s):  
Heat Transfer ◽  
Shape Optimization ◽  
Tangential Force ◽  
Turbine Blades ◽  
Leading Edge ◽  
Optimization Techniques ◽  
Multidisciplinary Optimization ◽  
Heat Transfer Analysis ◽  
Maximum Temperature ◽  
Force Coefficient

A multidisciplinary optimization procedure, with the integration of aerodynamic and heat transfer criteria, has been developed for the design of gas turbine blades. Two different optimization formulations have been used. In the first formulation, the maximum temperature in the blade section is chosen as the objective function to be minimized. An upper bound constraint is imposed on the blade average temperature and a lower bound constraint is imposed on the blade tangential force coefficient. In the second formulation, the blade average and maximum temperatures are chosen as objective functions. In both formulations, bounds are imposed on the velocity gradients at several points along the surface of the airfoil to eliminate leading edge velocity spikes which deteriorate aerodynamic performance. Shape optimization is performed using the blade external and coolant path geometric parameters as design variables. Aerodynamic analysis is performed using a panel code. Heat transfer analysis is performed using the finite element method. A gradient based procedure in conjunction with an approximate analysis technique is used for optimization. The results obtained using both optimization techniques are compared with a reference geometry. Both techniques yield significant improvements with the multiobjective formulation resulting in slightly superior design.

Heat Transfer Enhancement in Triangular Ducts With an Array of Side-Entry Wall/Impinged Jets

1999 ◽  
Author(s):  
J.-J. Hwang ◽  
C.-S. Cheng ◽  
Y.-P. Tsia
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Leading Edge ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Transfer Enhancement ◽  
Transfer Coefficients ◽  
Pressure Drops ◽  
Heat Transfer Coefficients ◽  
Inclined Angle

An experimental study has been performed to measure local heat transfer coefficients and static well pressure drops in leading-edge triangular ducts cooled by wall/impinged jets. Coolant provided by an array of equally spaced wall jets is aimed at the leading-edge apex and exits from the radial outlet. Detailed heat transfer coefficients are measured for the two walls forming the apex using transient liquid crystal technique. Secondary-flow structures are visualized to realize the mechanism of heat transfer enhancement by wall/impinged jets. Three right-triangular ducts of the same altitude and different apex angles of β = 30 deg (Duct A), 45 deg (Duct B) and 60 deg (Duct C) are tested for various jet Reynolds numbers (3000≦Rej≦12600) and jet spacings (s/d = 3.0 and 6.0). Results show that an increase in Rej increases the heat transfer on both walls. Local heat transfer on both walls gradually decreases downstream due to the crossflow effect. At the same Rej, the Duct C has the highest wall-averaged heat transfer because of the highest jet center velocity as well as the smallest jet inclined angle. Moreover, the distribution of static pressure drop based on the local through flow rate in the present triangular duct is similar to that that of developing straight pipe flows. Average jet Nusselt numbers on the both walls have been correlated with jet Reynolds number for three different duct shapes.

scholarly journals Highly Resolved Distribution of Heat Transfer for Turbine Leading Edge Film Cooling Including Reynolds Number and Blowing Rate Effects

1998 ◽  
Author(s):  
K. Jung ◽  
D. K. Hennecke
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Reynolds Number ◽  
Film Cooling ◽  
Heat Mass Transfer ◽  
Leading Edge ◽  
Transfer Coefficients ◽  
Complex Flow ◽  
Long Distance ◽  
Naphthalene Sublimation Technique

The effect of leading edge film cooling on heat transfer was experimentally investigated using the naphthalene sublimation technique. The experiments were performed on a symmetrical model of the leading edge suction side region of a high pressure turbine blade with one row of film cooling holes on each side. Two different lateral inclinations of the injection holes were studied: 0° and 45°. In order to build a data base for the validation and improvement of numerical computations, highly resolved distributions of the heat/mass transfer coefficients were measured. Reynolds numbers (based on hole diameter) were varied from 4000 to 8000 and blowing rate from 0.0 to 1.5. For better interpretation, the results were compared with injection-flow visualizations. Increasing the blowing rate causes more interaction between the jets and the mainstream, which creates higher jet turbulence at the exit of the holes resulting in a higher relative heat transfer. This increase remains constant over quite a long distance dependent on the Reynolds number. Increasing the Reynolds number keeps the jets closer to the wall resulting in higher relative heat transfer. The highly resolved heat/mass transfer distribution shows the influence of the complex flow field in the near hole region on the heat transfer values along the surface.

Clocking Effects of Inlet Non-Uniformities in a Fully Cooled High-Pressure Vane: A Conjugate Heat Transfer Analysis

2015 ◽  
Author(s):  
Duccio Griffini ◽  
Massimiliano Insinna ◽  
Simone Salvadori ◽  
Francesco Martelli
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Film Cooling ◽  
Conjugate Heat Transfer ◽  
Cooling System ◽  
Hot Spot ◽  
Three Dimensional ◽  
Leading Edge ◽  
Suction Side ◽  
Heat Transfer Analysis

A high-pressure vane equipped with a realistic film-cooling configuration has been studied. The vane is characterized by the presence of multiple rows of fan-shaped holes along pressure and suction side while the leading edge is protected by a showerhead system of cylindrical holes. Steady three-dimensional Reynolds-Averaged Navier-Stokes (RANS) simulations have been performed. A preliminary grid sensitivity analysis with uniform inlet flow has been used to quantify the effect of spatial discretization. Turbulence model has been assessed in comparison with available experimental data. The effects of the relative alignment between combustion chamber and high-pressure vanes are then investigated considering realistic inflow conditions in terms of hot spot and swirl. The inlet profiles used are derived from the EU-funded project TATEF2. Two different clocking positions are considered: the first one where hot spot and swirl core are aligned with passage and the second one where they are aligned with the leading edge. Comparisons between metal temperature distributions obtained from conjugate heat transfer simulations are performed evidencing the role of swirl in determining both the hot streak trajectory within the passage and the coolant redistribution. The leading edge aligned configuration is resulted to be the most problematic in terms of thermal load, leading to increased average and local vane temperature peaks on both suction side and pressure side with respect to the passage aligned case. A strong sensitivity of both injected coolant mass flow and heat removed by heat sink effect has also been highlighted for the showerhead cooling system.

Application of Conjugate Heat Transfer Analysis to Improvement of Cooled Turbine Vane and Blade for Industrial Gas Turbine

2018 ◽  
Author(s):  
Takeshi Horiuchi ◽  
Tomoki Taniguchi ◽  
Ryozo Tanaka ◽  
Masanori Ryu ◽  
Masahide Kazari
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Conjugate Heat Transfer ◽  
Metal Temperature ◽  
Heat Transfer Analysis ◽  
Estimation Accuracy ◽  
Cooling Performance ◽  
Measurement Results ◽  
Turbine Airfoils ◽  
Industrial Gas Turbine

In this paper, the Conjugate Heat Transfer (CHT) analysis, which utilizes commercial software STAR-CCM+ with detailed models and practical mesh size, was performed to the first stage cooled turbine airfoils for an industrial gas turbine produced by Kawasaki Heavy Industries, Ltd. (KHI). First its estimation accuracy was evaluated by comparing with the measurement results obtained with thermal index paint (TIP) and a pyrometer. After the validation of the CHT analysis, the metal temperature distribution was understood with the flow phenomena associated with it from the analysis results. To the parts where the metal temperature is locally high, then, the improvements of the cooling performance were considered with the CHT analysis and their effects were finally confirmed by measuring the metal temperature in the actual engine. The investigation reveals that the CHT analysis, which is validated with measurement results, makes it possible for cooling designers to efficiently improve the cooling performance of turbine airfoils with the adequate estimation accuracy, thus enhancing their durability for the reliability of gas turbines.

scholarly journals Research on Heat Transfer Dynamic Characteristics of Composite Layer Based on Laplace Transform

2019 ◽  
Author(s):  
Chunyu Xu ◽  
Junhua Lin ◽  
Wenhao Liu ◽  
Yuanbiao Zhang
Keyword(s):  
Heat Transfer ◽  
Composite Materials ◽  
Temperature Distribution ◽  
Transfer Function ◽  
Dynamic Characteristics ◽  
Transfer Functions ◽  
Composite Layer ◽  
Engineering Application ◽  
Second Order ◽  
Inverse Transformation

This paper predict and effectively control the temperature distribution of the steady-state and transient states of anisotropic four-layer composite materials online, knowing the density, specific heat, heat conductivity and thickness of the composite materials. Based on the transfer function, a mathematical model was established to study the dynamic characteristics of heat transfer of the composite materials. First of all, the Fourier heat transfer law was used to establish a one-dimensional Fourier heat conduction differential equation for each composite layer, and the Laplace transformation was carried out to obtain the system function. Then the approximate second-order transfer function of the system was obtained by Taylor expansion, and the Laplace inverse transformation was carried out to obtain the transfer function of the whole system in the time domain. Finally, the accuracy of the simplified analytical solutions of the first, second and third order approximate transfer functions was compared with computer simulation. The results showed that the second order approximate transfer functions can describe the dynamic process of heat transfer better than others. The research on the dynamic characteristics of heat transfer in the composite layer and the dynamic model of heat transfer in composite layer proposed in this paper have a reference value for practical engineering application. It can effectively predict the temperature distribution of composite layer material and reduce the cost of experimental measurement of heat transfer performance of materials.

Optimization of Vortex Promoter Parameters to Enhance Heat Transfer Rate in Electronic Equipment

2019 ◽  
Vol 12 (2) ◽  
Author(s):  
Ece Aylı ◽  
Özgür Bayer
Keyword(s):  
Heat Transfer ◽  
Reynolds Numbers ◽  
Maximum Temperature ◽  
Transfer Coefficients ◽  
Enhance Heat Transfer ◽  
Distance Ratio ◽  
Heat Transfer Coefficients ◽  
Optimization Study ◽  
Finned Surface ◽  
Lower Temperature

Abstract In this paper, optimization of the location and the geometry of a vortex promoter located above in a finned surface in a channel with eight heat sources is investigated for a Reynolds number of 12,500 < Re < 27,700. Heat transfer rates and the corresponding Nusselt number distributions are studied both experimentally and numerically using different vortex promoter geometries (square, circular, and triangular) in different locations to illustrate the effect of vortex promoter on the fluid flow. Optimization study considered a range of following parameters: blockage ratio of 0.30 < (y/C) < 0.45 and interpromoter distance ratio of 0.2277 < (x/L) < 0.3416. Results show that fins over which rectangular and circular promoters are integrated perform better in enhancing the heat transfer. According to the numerical and experimental results, higher blockage ratios cause significantly higher heat transfer coefficients. According to the observations, as the interpromoter distances increase, shedding gains strength, and more turbulence is created. All vortex promoters enhance heat transfer resulting in lower temperature values on the finned surface for different (y/C) and (x/L) values and Reynolds numbers. The use of promoters enhances the heat transfer, and the decrease in the maximum temperature values is recorded on the finned surface changing between 15% and 27%. The biggest decrease in maximum surface temperature value is 500 K–364 K and observed in circular promoter case with (y/C) = 0.43, (x/L) = 0.3416, and Reynolds numbers of 22,200.

Comparison of Predictions From Conjugate Heat Transfer Analysis of a Film-Cooled Turbine Vane to Experimental Data

2013 ◽  
Author(s):  
Ron-Ho Ni ◽  
William Humber ◽  
George Fan ◽  
John P. Clark ◽  
Richard J. Anthony ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Conjugate Heat Transfer ◽  
Metal Temperature ◽  
Heat Transfer Analysis ◽  
Barrier Coating ◽  
Turbine Vane ◽  
Flux Measurements ◽  
Surface Metal ◽  
Air Force Research Laboratory

Conjugate heat transfer analysis was conducted on a 648 hole film cooled turbine vane using Code Leo and compared to experimental results obtained at the Air Force Research Laboratory Turbine Research Facility. An unstructured mesh with fully resolved film holes for both fluid and solid domains was used to conduct the conjugate heat transfer simulation on a desktop PC with eight cores. Initial heat flux and surface metal temperature predictions showed reasonable agreement with heat flux measurements but under prediction of surface metal temperature values. Root cause analysis was performed, leading to two refinements. First, a thermal barrier coating layer was introduced into the analysis to account for the insulating properties of the Kapton layer used for the heat flux gauges. Second, inlet boundary conditions were updated to more accurately reflect rig measurement conditions. The resulting surface metal temperature predictions showed excellent agreement relative to measured results (+/− 5 degrees K).

Experimental Evaluations of the Relative Contributions to Overall Effectiveness in Turbine Blade Leading Edge Cooling

2018 ◽  
Author(s):  
Carol E. Bryant ◽  
Connor J. Wiese ◽  
James L. Rutledge ◽  
Marc D. Polanka
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Leading Edge ◽  
Internal Surface ◽  
Internal Cooling ◽  
Transfer Coefficients ◽  
Impingement Cooling ◽  
External Cooling ◽  
Turbine Component ◽  
Overall Effectiveness

Gas turbine hot gas path components are protected through a combination of internal cooling and external film cooling. The coolant typically travels through internal passageways, which may involve impingement on the internal surface of a turbine component, before being ejected as film cooling. Internal cooling effects have been studied in facilities that allow measurement of heat transfer coefficients within models of the internal cooling paths, with large heat transfer coefficients generally desirable. External film cooling is typically evaluated through measurements of the adiabatic effectiveness and its effect on the external heat transfer coefficient. Efforts aimed at improving cooling are often focused on either only the internal cooling or the film cooling; however, the common coolant flow means the internal and external cooling schemes are linked and the coolant holes themselves provide another convective path for heat transfer to the coolant. Recently, measurements of overall cooling effectiveness using matched Biot number turbine component models allow evaluation of the nondimensional wall temperature achieved for the fully cooled component. However, the relative contributions of internal cooling, external cooling, and convection within the film cooling holes is not well understood. Large scale, matched Biot number experiments, complemented by CFD simulations, were performed on a fully film cooled cylindrical leading edge model to evaluate the effects of various alterations in the cooling design on the overall effectiveness. The relative influence of film cooling and cooling within the holes was evaluated by selectively disabling individual holes and quantifying how the overall effectiveness changed. Several internal impingement cooling schemes in addition to a baseline case without impingement cooling were also tested. In general, impingement cooling is shown to have a negligible influence on the overall effectiveness in the showerhead region. This indicates that the cost and pressure drop penalties for implementing impingement cooling may not be compensated by an increase in thermal performance. Instead, the internal cooling provided by convection within the holes themselves was shown, along with external film cooling, to be a dominant contribution to the overall cooling effectiveness. Indeed, the numerous holes within the showerhead region impede the ability of internal surface cooling schemes to influence the outside surface temperature. The results of this research may allow improved focus of future efforts on the forms of cooling with the greatest potential to improve cooling performance.

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