scholarly journals Estimation of internal heat transfer coefficients and detection of rib positions in gas turbine blades from transient surface temperature measurements

2008 ◽  
Vol 135 ◽  
pp. 012050 ◽  
Author(s):  
P Heidrich ◽  
J v Wolfersdorf ◽  
S Schmidt ◽  
M Schnieder
Keyword(s):  
Heat Transfer ◽  
Surface Temperature ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Internal Heat ◽  
Temperature Measurements ◽  
Transfer Coefficients ◽  
Gas Turbine Blades ◽  
Heat Transfer Coefficients ◽  
Internal Heat Transfer

Laminar and Transitional Boundary Layer Structures in Accelerating Flow With Heat Transfer

1986 ◽  
Vol 108 (1) ◽  
pp. 116-123 ◽  
Author(s):  
K. Rued ◽  
S. Wittig
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Pressure Gradients ◽  
Transfer Coefficients ◽  
Gas Turbine Blades ◽  
Heat Transfer Coefficients ◽  
Layer Structures ◽  
Flow Heat

The accurate prediction of heat transfer coefficients on cooled gas turbine blades requires consideration of various influence parameters. The present study continues previous work with special efforts to determine the separate effects of each of several parameters important in turbine flow. Heat transfer and boundary layer measurements were performed along a cooled flat plate with various freestream turbulence levels (Tu = 1.6−11 percent), pressure gradients (k = 0−6 × 10−6), and cooling intensities (Tw/T∞ = 1.0−0.53). Whereas the majority of previously available results were obtained from adiabatic or only slightly heated surfaces, the present study is directed mainly toward application on highly cooled surfaces as found in gas turbine engines.

Heat Transfer in a Vane Trailing Edge Passage With Conical Pins and Pin-Turbulator Integrated Configurations

2014 ◽  
Author(s):  
J. Kruekels ◽  
S. Naik ◽  
A. Lerch ◽  
A. Sedlov
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Gas Turbine ◽  
Internal Heat ◽  
Transfer Coefficients ◽  
Trailing Edge ◽  
Heat Transfer Coefficients ◽  
Trailing Edges ◽  
Converging Channel ◽  
Internal Heat Transfer

The trailing edge sections of gas turbine vanes and blades are generally subjected to extremely high heat loads due to the combined effects of high external accelerating Mach numbers and gas temperatures. In order to maintain the metal temperatures of these trailing edges to a level, which fulfills the mechanical integrity of the parts, highly efficient cooling of the trailing edges is required without increasing the coolant consumption, as the latter has a detrimental effect on the overall gas turbine performance. In this paper the characteristics of the heat transfer and pressure drop of two novel integrated pin bank configurations were investigated. These include a pin bank with conical pins and a pin bank consisting of cylindrical pins and intersecting broken turbulators. As baseline case, a pin bank with cylindrical pins was studied as well. All investigations were done in a converging channel in order to be consistent with the real part. The heat transfer and pressure drop of all the pin banks were investigated initially with the use of numerical predictions and subsequently in a scaled experimental wind tunnel. The experimental study was conducted for a range of operational Reynolds numbers. The TLC (thermochromic liquid crystal) method was used to measure the detailed heat transfer coefficients in scaled Perspex models representing the various pin bank configurations. Pressure taps were located at several positions within the test sections. Both local and average heat transfer coefficients and pressure loss coefficients were determined. The measured and predicted results showed that the local internal heat transfer coefficient increases in the flow direction. This was due to the flow acceleration in the converging channel. Furthermore, both the broken ribs and the conical pin banks resulted in higher heat transfer coefficients compared with the baseline cylindrical pins. The conical pins produced the highest average internal heat transfer coefficients in contrast to the pins with the broken ribs, though this was also associated with a higher pressure drop.

Calculation of Heat Transfer to Convection-Cooled Gas Turbine Blades

1985 ◽  
Vol 107 (3) ◽  
pp. 620-627 ◽  
Author(s):  
W. Rodi ◽  
G. Scheuerer
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Complex Nature ◽  
Surface Boundary ◽  
Transfer Coefficients ◽  
Free Stream Turbulence ◽  
Gas Turbine Blades ◽  
Heat Transfer Coefficients

A mathematical model is presented for calculating the external heat transfer coefficients around gas turbine blades. The model is based on a finite-difference procedure for solving the boundary-layer equations which describe the flow and temperature field around the blades. The effects of turbulence are simulated by a low-Reynolds number version of the k-ε turbulence model. This allows calculation of laminar and transitional zones and also the onset of transition. Applications of the calculation method are presented to turbine-blade situations which have recently been investigated experimentally. Predicted and measured heat transfer coefficients are compared and good agreement with the data is observed. This is true especially for the pressure-surface boundary layer which is of a rather complex nature because it remains in a transitional state over the full blade length. The influence of various flow phenomena like laminar-turbulent transition and of the boundary conditions (pressure gradient, free-stream turbulence) on the predicted heat transfer rates is discussed.

The Measurement of Full-Surface Internal Heat Transfer Coefficients for Turbine Airfoils Using a Nondestructive Thermal Inertia Technique

2003 ◽  
Vol 125 (1) ◽  
pp. 83-89 ◽  
Author(s):  
Nirm V. Nirmalan ◽  
Ronald S. Bunker ◽  
Carl R. Hedlund
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Surface Temperature ◽  
Transfer Coefficient ◽  
External Surface ◽  
Internal Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Turbine Airfoils ◽  
Internal Heat Transfer

A new method has been developed and demonstrated for the non-destructive, quantitative assessment of internal heat transfer coefficient distributions of cooled metallic turbine airfoils. The technique employs the acquisition of full-surface external surface temperature data in response to a thermal transient induced by internal heating/cooling, in conjunction with knowledge of the part wall thickness and geometry, material properties, and internal fluid temperatures. An imaging Infrared camera system is used to record the complete time history of the external surface temperature response during a transient initiated by the introduction of a convecting fluid through the cooling circuit of the part. The transient data obtained is combined with the cooling fluid network model to provide the boundary conditions for a finite element model representing the complete part geometry. A simple 1-D lumped thermal capacitance model for each local wall position is used to provide a first estimate of the internal surface heat transfer coefficient distribution. A 3-D inverse transient conduction model of the part is then executed with updated internal heat transfer coefficients until convergence is reached with the experimentally measured external wall temperatures as a function of time. This new technique makes possible the accurate quantification of full-surface internal heat transfer coefficient distributions for prototype and production metallic airfoils in a totally nondestructive and non-intrusive manner. The technique is equally applicable to other material types and other cooled/heated components.

Experimental Study of Internal Heat Transfer Coefficients in a Rectangular, Ribbed Channel Using a Non-Invasive, Non-Destructive, Transient Inverse Method

2008 ◽  
Author(s):  
Peter Heidrich ◽  
Jens von Wolfersdorf ◽  
Martin Schnieder
Keyword(s):  
Heat Transfer ◽  
Measurement Method ◽  
Inverse Method ◽  
Turbine Blades ◽  
Internal Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Non Invasive ◽  
Non Destructive ◽  
Internal Heat Transfer

This paper describes a non-invasive, non-destructive inverse measurement method that allows one to determine heat transfer coefficients in internal passages of real turbine blades experimentally. For this purpose, a test rig with a fast responding heater was designed to fulfill the requirement of a sudden increase in the air temperature within the internal cooling passages. The outer surface temperatures of the specimen were measured using an infrared camera. To suggest the spatial distribution of the internal heat transfer coefficients from the transient characteristics of the outside surface temperature the inverse heat transfer problem was solved. Differing from former studies which made a thin wall assumption, the conduction inside a finite wall was modelled. Based on a one-dimensional forward solution the best fitting optimization method, the Levenberg-Marquardt algorithm, was chosen. This was verified with artificial data including random noise with positive results. Experimental data were measured for a rectangular H/W = 1:4 aspect ratio channel made of stainless steel with parallel 90° and 45° ribs at Reynolds numbers from 25,000 to 80,000. Results of 90° ribs were compared with simultaneously acquired data using the transient liquid crystal technique. Furthermore the influence of Reynolds number on pitch averaged heat transfer results were evaluated for both rib configurations. These results based on infrared data were compared with earlier studies. It is concluded that the presented experimental measurement method using the transient inverse method could be used to quantitatively determine heat transfer coefficients in internal passages of real turbine blades.

Determination of Heat Transfer Coefficients Around a Blade Surface From Temperature Measurements

1979 ◽  
Author(s):  
D. K. Mukherjee
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Operating Conditions ◽  
Main Stream ◽  
Blade Surface ◽  
Transfer Coefficients ◽  
Gas Turbine Blades ◽  
Heat Transfer Coefficients

To design cooled gas turbine blades, heat transfer coefficients around its surface are required. The calculated heat transfer data under operating conditions in the turbine are often inaccurate and require experimental verification. A method is presented here to determine the heat transfer coefficients around the blade surface and in the coolant channels. This requires measurements of the main stream and coolant temperatures together with the outer surface temperature distribution at varying mass flows. In order to conduct these tests in a gas turbine, test blades have to be specially prepared allowing the variation and measurement of coolant mass flow.

The Measurement of Full-Surface Internal Heat Transfer Coefficients for Turbine Airfoils Using a Non-Destructive Thermal Inertia Technique

2002 ◽  
Author(s):  
Nirm V. Nirmalan ◽  
Ronald S. Bunker ◽  
Carl R. Hedlung
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
External Surface ◽  
Internal Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Turbine Airfoils ◽  
Non Destructive ◽  
Internal Heat Transfer

A new method has been developed and demonstrated for the non-destructive, quantitative assessment of internal heat transfer coefficient distributions of cooled metallic turbine airfoils. The technique employs the acquisition of full-surface external surface temperature data in response to a thermal transient induced by internal heating/cooling, in conjunction with knowledge of the part wall thickness and geometry, material properties, and internal fluid temperatures. An imaging Infrared camera system is used to record the complete time history of the external surface temperature response during a transient initiated by the introduction of a convecting fluid through the cooling circuit of the part. The transient data obtained is combined with the cooling fluid network model to provide the boundary conditions for a finite element model representing the complete part geometry. A simple 1D lumped thermal capacitance model for each local wall position is used to provide a first estimate of the internal surface heat transfer coefficient distribution. A 3D inverse transient conduction model of the part is then executed with updated internal heat transfer coefficients until convergence is reached with the experimentally measured external wall temperatures as a function of time. This new technique makes possible the accurate quantification of full-surface internal heat transfer coefficient distributions for prototype and production metallic airfoils in a totally non-destructive and non-intrusive manner. The technique is equally applicable to other material types and other cooled/heated components.

scholarly journals Effect of Discrete Ribs on Heat Transfer and Friction Inside Narrow Rectangular Cross Section Cooling Passage of Gas Turbine Blade

2021 ◽  
Vol 10 (6) ◽  
pp. 192-209
Author(s):  
Karthik Krishnaswamy ◽  
◽  
Srikanth Salyan ◽  
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Turbine Blades ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Hydraulic Diameter ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Cooling Passage

The performance of a gas turbine during the service life can be enhanced by cooling the turbine blades efficiently. The objective of this study is to achieve high thermohydraulic performance (THP) inside a cooling passage of a turbine blade having aspect ratio (AR) 1:5 by using discrete W and V-shaped ribs. Hydraulic diameter (Dh) of the cooling passage is 50 mm. Ribs are positioned facing downstream with angle-of-attack (α) of 30° and 45° for discrete W-ribs and discerte V-ribs respectively. The rib profiles with rib height to hydraulic diameter ratio (e/Dh) or blockage ratio 0.06 and pitch (P) 36 mm are tested for Reynolds number (Re) range 30000-75000. Analysis reveals that, area averaged Nusselt numbers of the rib profiles are comparable, with maximum difference of 6% at Re 30000, which is within the limits of uncertainty. Variation of local heat transfer coefficients along the stream exhibited a saw tooth profile, with discrete W-ribs exhibiting higher variations. Along spanwise direction, discrete V-ribs showed larger variations. Maximum variation in local heat transfer coefficients is estimated to be 25%. For experimented Re range, friction loss for discrete W-ribs is higher than discrete-V ribs. Rib profiles exhibited superior heat transfer capabilities. The best Nu/Nuo achieved for discrete Vribs is 3.4 and discrete W-ribs is 3.6. In view of superior heat transfer capabilities, ribs can be deployed in cooling passages near the leading edge, where the temperatures are very high. The best THPo achieved is 3.2 for discrete V-ribs and 3 for discrete W-ribs at Re 30000. The ribs can also enhance the power-toweight ratio as they can produce high thermohydraulic performances for low blockage ratios.

scholarly journals Verification of Thermal Models of Internally Cooled Gas Turbine Blades

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Igor Shevchenko ◽  
Nikolay Rogalev ◽  
Andrey Rogalev ◽  
Andrey Vegera ◽  
Nikolay Bychkov
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Heat Removal ◽  
Leading Edge ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Transfer Coefficients ◽  
Single Experiment ◽  
Heat Transfer Coefficients

Numerical simulation of temperature field of cooled turbine blades is a required element of gas turbine engine design process. The verification is usually performed on the basis of results of test of full-size blade prototype on a gas-dynamic test bench. A method of calorimetric measurement in a molten metal thermostat for verification of a thermal model of cooled blade is proposed in this paper. The method allows obtaining local values of heat flux in each point of blade surface within a single experiment. The error of determination of local heat transfer coefficients using this method does not exceed 8% for blades with radial channels. An important feature of the method is that the heat load remains unchanged during the experiment and the blade outer surface temperature equals zinc melting point. The verification of thermal-hydraulic model of high-pressure turbine blade with cooling allowing asymmetrical heat removal from pressure and suction sides was carried out using the developed method. An analysis of heat transfer coefficients confirmed the high level of heat transfer in the leading edge, whose value is comparable with jet impingement heat transfer. The maximum of the heat transfer coefficients is shifted from the critical point of the leading edge to the pressure side.

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