scholarly journals Mach Number Effects on Turbine Blade Transition Length Prediction

1998 ◽  
Author(s):  
R. J. Boyle ◽  
F. F. Simon
Keyword(s):  
Heat Transfer ◽  
Mach Number ◽  
Production Rate ◽  
Turbine Blade ◽  
Film Cooling ◽  
Turbine Blades ◽  
Navier Stokes ◽  
Data Sets ◽  
Speed Flow ◽  
Transition Length

The effect of a Mach number correction on a model for predicting the length of transition was investigated. The transition length decreases as the turbulent spot production rate increases. Much of the data for predicting the spot production rate comes from low speed flow experiments. Recent data and analysis showed that the spot production rate is affected by Mach number. The degree of agreement between analysis and data for turbine blade heat transfer without film cooling is strongly dependent of accurately predicting the length of transition. Consequently, turbine blade heat transfer data sets were used to validate a transition length turbulence model. A method for modifying models for the length of transition to account for Mach number effects is presented. The modification was made to two transition length models. The modified models were incorporated into the two-dimensional Navier-Stokes code, RVCQ3D. Comparisons were made between predicted and measured midspan surface heat transfer for stator and rotor turbine blades. The results showed that accounting for Mach number effects significantly improved the agreement with the experimental data.

scholarly journals Mach Number Effects on Turbine Blade Transition Length Prediction

1999 ◽  
Vol 121 (4) ◽  
pp. 694-702 ◽  
Author(s):  
R. J. Boyle ◽  
F. F. Simon
Keyword(s):  
Heat Transfer ◽  
Mach Number ◽  
Production Rate ◽  
Turbine Blade ◽  
Film Cooling ◽  
Turbine Blades ◽  
Navier Stokes ◽  
Data Sets ◽  
Speed Flow ◽  
Transition Length

The effect of a Mach number correction on a model for predicting the length of transition was investigated. The transition length decreases as the turbulent spot production rate increases. Many of the data for predicting the spot production rate come from low-speed flow experiments. Recent data and analysis showed that the spot production rate is affected by Mach number. The degree of agreement between analysis and data for turbine blade heat transfer without film cooling is strongly dependent on accurately predicting the length of transition. Consequently, turbine blade heat transfer data sets were used to validate a transition length turbulence model. A method for modifying models for the length of transition to account for Mach number effects is presented. The modification was made to two transition length models. The modified models were incorporated into the two-dimensional Navier–Stokes code, RVCQ3D. Comparisons were made between predicted and measured midspan surface heat transfer for stator and rotor turbine blades. The results showed that accounting for Mach number effects significantly improved the agreement with the experimental data.

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.

Effects of Turbulence Intensity and Scale on Turbine Blade Heat Transfer

2015 ◽  
Author(s):  
Robert J. Boyle ◽  
Ali A. Ameri
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Turbine Blade ◽  
Turbulence Intensity ◽  
Film Cooling ◽  
Rotor Blade ◽  
Navier Stokes ◽  
Test Cases ◽  
Freestream Turbulence ◽  
Turbulence Scale

The effects of turbulence intensity and length scale on turbine blade heat transfer and aerodynamic losses are investigated. The importance of freestream turbulence on heat transfer increases with Reynolds number and turbulence intensity, and future turbine blade Reynolds numbers are expected to be higher than in current engines. Even when film cooling is used, accurate knowledge of baseline heat transfer distributions are needed. Heat flux reductions due to film cooling depend on the ratio of film cooled-to-solid blade heat transfer coefficients. Comparisons are made between published experimental data and published correlations for leading edge heat transfer. Stagnation region heat transfer rates of vanes and blades of high pressure turbines can be nearly double those predicted when predictions neglect freestream turbulence effects. Correlations which included the scale of turbulence gave better agreement with data. Two-dimensional Navier-Stokes analysis were done for several existing test cases where measures of the turbulence scale are available. The test cases had significant regions where the flow was not fully turbulent. Freestream turbulence increases laminar heat transfer, but has little influence on turbulent heat transfer. The Navier-Stokes analysis included a model for the effects of high freestream turbulence on laminar or transitioning boundary layers. Comparisons were made with vane and rotor blade data, as well as with high Reynolds number test data that simulated the favorable pressure gradient regions seen in the forward portions of turbine blades. Predictions of surface heat transfer showed the appropriate trends in heat transfer with turbulence intensity and turbulence scale. However, the absolute level of agreement indicated that further verification of approaches to predicting turbulence intensity and scale effects is needed. Significant increases in losses were calculated for vane and rotor blade geometries as inlet turbulence increased.

scholarly journals Computational Modeling and Thermal Paint Verification of Film-Cooling Designs for an Unshrouded High-Pressure Turbine Blade

1999 ◽  
Author(s):  
Steven G. Gegg ◽  
Nathan J. Heidegger ◽  
Ronald A. Mikkelson
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Turbine Blade ◽  
Film Cooling ◽  
Data Exchange ◽  
Turbine Blades ◽  
Inlet Temperature ◽  
High Pressure Turbine ◽  
Extreme High Temperature ◽  
Blade Tip

High pressure turbine blades are exposed to an extreme high temperature environment due to increasing turbine inlet temperature. High heat fluxes are likely on the blade pressure surface. Other regions, such as the trailing edge and blade tip may be difficult to cool uniformly. Unshrouded blades present an additional challenge due to the pressure driven transport of hot gas across the blade tip. The blade tip region is therefore prone to severe thermal stress, fatigue and oxidation. In order to develop effective cooling methods, designers require detailed flow and heat transfer information. This paper reports on computational aerodynamics and heat transfer studies for an unshrouded high pressure turbine blade. The emphasis is placed on the application of appropriate 3-D models for the prediction of airfoil surface temperatures. Details of the film cooling model, boundary conditions and data exchange with heat transfer models are described. The analysis approach has been refined for design use to provide timely and accurate results. Film cooling designs are to be tailored for the best coverage of the blade tip region. Designs include near-tip pressure side films and blade tip cooling holes. Hole placement and angle are investigated to achieve the best coolant coverage on the blade tip. Analytical results are compared to a thermal paint test on engine hardware. In addition to film cooling strategies, other aerodynamic/heat transfer design approaches are discussed to address the cooling requirements for an unshrouded blade.

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 numerical and experimental investigations of heat transfer of a highly loaded low-pressure turbine blade under periodic inlet flow condition

2018 ◽  
Vol 232 (7) ◽  
pp. 769-784 ◽  
Author(s):  
Ali Nikparto ◽  
Meinhard T Schobeiri
Keyword(s):  
Heat Transfer ◽  
Unsteady Flow ◽  
Turbine Blade ◽  
Flow Condition ◽  
Turbine Blades ◽  
Low Pressure ◽  
Navier Stokes ◽  
Predictive Capability ◽  
Low Pressure Turbine ◽  
Calculation Results

This paper experimentally and numerically investigates heat transfer characteristics of a low-pressure turbine blade under steady/unsteady flow conditions. Generally, the low-pressure turbine blades are not exposed to excessive temperatures that require detailed heat transfer predictions. In aircraft engines, they operate at low Re-numbers causing the inception of large separation bubbles on their suction surface. As documented in previous papers, the results of detailed aerodynamic simulations have shown significant discrepancies with experiments. It was the objective of the current investigation to determine the discrepancies between the experimental and numerical heat transfer results. It is shown that small errors in aero-calculation results in large deviations of heat transfer results. The characteristics of the blades mentioned above, make low-pressure turbine blades suitable candidates for evaluating the predictive capability of any numerical method. Documenting the scope of these discrepancies defines the framework of the current paper. The periodic flow inside the gas turbine engine was simulated using the cascade facility at the Turbomachinery Performance and Flow Research Laboratory (TPFL) of Texas A&M University. In this study, the wakes that originate from stator blades were simulated by moving rods. The instrumented blade was covered with a liquid crystal sheet and it was used to measure heat transfer coefficient. Reynolds-averaged Navier–Stokes equations were used for numerical investigation purposes. Measurements and simulations were conducted at three different Reynolds numbers (110,000, 150,000, and 250,000). Furthermore, for unsteady flow condition, reduced frequencies of the incoming wakes were varied. The current paper includes a comprehensive heat transfer assessment of the predictive capability of Reynolds-averaged Navier–Stokes based tools. The effect of the separation bubbles on heat transfer is thoroughly discussed in this paper. Comparisons of the experimental and numerical results detail the differences and identify the sources of error that leads to in accurate calculations in terms of predicting heat transfer calculation results.

scholarly journals Comparison of Two-Equation Turbulence Models for Prediction of Heat Transfer on Film-Cooled Turbine Blades

1997 ◽  
Author(s):  
Vijay K. Garg ◽  
Ali A. Ameri
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Computer Time ◽  
Suction Surface ◽  
The Heat Transfer Coefficient

A three-dimensional Navier-Stokes code has been used to compute the heat transfer coefficient on two film-cooled turbine blades, namely the VKI rotor with six rows of cooling holes including three rows on the shower head, and the C3X vane with nine rows of holes including five rows on the shower head. Predictions of heat transfer coefficient at the blade surface using three two-equation turbulence models, specifically, Coakley’s q-ω model, Chien’s k-ε model and Wilcox’s k-ω model with Menter’s modifications, have been compared with the experimental data of Camci and Arts (1990) for the VKI rotor, and of Hylton et al. (1988) for the C3X vane along with predictions using the Baldwin-Lomax (B-L) model taken from Garg and Gaugler (1995). It is found that for the cases considered here the two-equation models predict the blade heat transfer somewhat better than the B-L model except immediately downstream of the film-cooling holes on the suction surface of the VKI rotor, and over most of the suction surface of the C3X vane. However, all two-equation models require 40% more computer core than the B-L model for solution, and while the q-ω and k-ε models need 40% more computer time than the B-L model, the k-ω model requires at least 65% more time due to slower rate of convergence. It is found that the heat transfer coefficient exhibits a strong spanwise as well as streamwise variation for both blades and all turbulence models.

Full-Coverage Film Cooling—Part II: Heat Transfer Data and Numerical Simulation

1980 ◽  
Vol 102 (4) ◽  
pp. 1006-1012 ◽  
Author(s):  
M. E. Crawford ◽  
W. M. Kays ◽  
R. J. Moffat
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Numerical Procedure ◽  
Stanton Number ◽  
Data Sets ◽  
Blowing Ratio ◽  
Diameter Hole ◽  
Full Coverage ◽  
Sample Data ◽  
Length Data

Experimental research into heat transfer from full-coverage film-cooled surfaces with three injection geometries was described in Part I. This part has two objectives. The first is to present a simple numerical procedure for simulation of heat transfer with full-coverage film cooling. The second objective is to present some of the Stanton number data that was used in Part I of the paper. The data chosen for presentation are the low-Reynolds number, heated-starting-length data for the three injection geometries with five-diameter hole spacing. Sample data sets with high blowing ratio and with ten-diameter hole spacing are also presented. The numerical procedure has been successfully applied to the Stanton number data sets.

Heat transfer and film cooling effectiveness on the squealer tip of a turbine blade

Energy ◽  
2014 ◽  
Vol 72 ◽  
pp. 331-343 ◽  
Author(s):  
Jun Su Park ◽  
Dong Hyun Lee ◽  
Dong-Ho Rhee ◽  
Shin Hyung Kang ◽  
Hyung Hee Cho
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Film Cooling ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness
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