THE INFLUENCE OF LONGITUDINAL PRESSURE GRADIENT AND TURBULENCE OF THE FLOW UPON HEAT TRANSFER IN TURBINE BLADES

1978 ◽  
Author(s):  
L. M. Zysina-Molozhen ◽  
M. A. Medvedeva ◽  
E. G. Rohst
Keyword(s):  
Heat Transfer ◽  
Pressure Gradient ◽  
Turbine Blades ◽  
Longitudinal Pressure Gradient

Three Dimensional Measurements of Instantaneous Flow Field in Corners With Smooth Surfaces Under a Zero Pressure Gradient

2004 ◽  
Author(s):  
Michael Phillips ◽  
Steve Deutsch ◽  
Arnie Fontaine ◽  
Savas Yavuzkurt
Keyword(s):  
Heat Transfer ◽  
Pressure Gradient ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Instantaneous Velocity ◽  
Stream Velocity ◽  
Internal Cooling ◽  
Mean Velocity ◽  
Data Set ◽  
Corner Flow

Three dimensional instantaneous velocity data were taken in a turbulent corner flow with smooth walls under a zero pressure gradient. Experiments were carried out in air with a free stream velocity of 13 m/s and an axial Reynolds number of about 10,000,000. The data were collected using a three-component LDV system that was configured in a nearly orthogonal setup. Measurements were made down to a y+ of approximately 5, and should provide a valuable data set in developing models and predictive codes. Data were collected at two axial locations, 0.93 and 1.26 m measured from the virtual origin. The boundary layer thickness was 20.90 mm and 24.91 mm respectively at these locations. At each position, instantaneous velocity profiles were measured at 6.35, 12.7, 20.6, 41.2, 82.3, 121.9, 164.5, 184.8, and 205.1 mm from the corner. The centerline profiles agree well with classical flat plate data. Three mean velocity and six Reynolds stress components have been calculated. The instantaneous velocity field data set is sufficient to compute higher order correlations. The data will be valuable for development of computer codes and models for heat transfer studies in the internal cooling channels of gas turbine blades and turbine end wall flow and heat transfer studies. An analysis of the data is presented. Future studies will concentrate on one smooth and one rough wall corner flow with favorable and adverse pressure gradients to provide a detailed database for corner flows in complex three dimensional flow fields.

scholarly journals Heat transfer behind the backward-facing step under the influence of longitudinal pressure gradient

2016 ◽  
Vol 92 ◽  
pp. 01030 ◽  
Author(s):  
Tatyana Bogatko ◽  
Viktor Terekhov ◽  
Aleksey Dyachenko ◽  
Yaroslav Smulsky
Keyword(s):  
Heat Transfer ◽  
Pressure Gradient ◽  
Backward Facing Step ◽  
Longitudinal Pressure Gradient

scholarly journals HEAT TRANSFER IN GRADIENT TURBULENT BOUNDARY LAYER

2019 ◽  
Vol 41 (4) ◽  
pp. 19-26
Author(s):  
A.A. Avramenko ◽  
M.M. Kovetskaya ◽  
E.A. Kondratieva ◽  
T.V. Sorokina
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Transfer Coefficient ◽  
Turbulent Boundary Layer ◽  
Pressure Gradient ◽  
Transfer Coefficient ◽  
Boundary Layer Separation ◽  
Variable Pressure ◽  
Flow Acceleration ◽  
Longitudinal Pressure Gradient

Effect of pressure gradient on heat transfer in turbulent boundary layer is constantly investigated during creation and improvement of heat exchange equipment for energy, aerospace, chemical and biological systems. The paper deals with problem of steady flow and heat  transfer in turbulent boundary layer with variable pressure in longitudinal direction. The mathematical model is presented and the analytical solution of heat transfer in the turbulent boundary layer problem at positive and negative pressure gradients is given. Dependences for temperature profiles and coefficient of heat transfer on flow parameters were obtained.  At negative longitudinal pressure gradient (flow acceleration) heat transfer coefficient can both increase and decrease. At beginning of acceleration zone, when laminarization effects are negligible, heat transfer coefficient increases. Then, as the flow laminarization increases, heat transfer coefficient decreases. This is caused by flow of turbulent energy transfers to accelerating flow. In case of positive longitudinal pressure gradient, temperature profile gradient near wall decreases. It is because of decreasing velocity gradient before zone of possible boundary layer separation.

On the Momentum and Thermal Structures of Turbulent Spots in a Favourable Pressure Gradient

2005 ◽  
Author(s):  
T. P. Chong ◽  
S. Zhong
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Pressure Gradient ◽  
Thermal Boundary Layer ◽  
Turbine Blades ◽  
Temperature Fluctuations ◽  
Turbulent Heat ◽  
Turbulent Spots ◽  
Zone Length ◽  
The Difference

This paper represents the results from an experimental investigation of the flow physics behind the difference in the transition zone length indicated by the momentum boundary layer and thermal boundary layer parameters observed on the suction surfaces of gas turbine blades. The experiments were carried out on turbulent spots created artificially in an otherwise laminar boundary layer developing over a heated flat plate in a zero pressure gradient and a favourable pressure gradient. A specially designed miniature triple wire probe was used to measure the streamwise velocity U, transverse velocity component V and temperature T simultaneously during the passage of the spots. In this paper, the general characteristics of the ensemble-averaged velocity and temperature perturbations, rms fluctuations and the second moment turbulent quantities are discussed and the influence of favourable pressure gradient on these parameters is examined. When a favourable pressure gradient is present, unlike in the velocity boundary layer where significant velocity fluctuations (or Reynolds shear stress) occur both on the plane of symmetry and the spanwise periphery, high temperature fluctuations (or turbulent heat fluxes) are confined in the plane of symmetry. The difference in the levels of velocity/temperature fluctuations at these two locations gives an indication of the effectiveness of momentum/heat transfer across the span of the spots. The results of this study show that the heat transfer within a spot is inhibited more than that of the momentum transfer at the presence of a favourable pressure gradient. This phenomenon is expected to slow down the spanwise growth of turbulent spots in the transitional thermal boundary layer, leading to a longer transitional zone length indicated by the heat transfer parameters as reported in the literature.

DESIGN AND STUDY OF EXCHANGERS WITH PRESSURE GRADIENT HEAT INTENSIFIERS

2018 ◽  
Vol 8 (3) ◽  
pp. 137-144
Author(s):  
Nadezhda P. PETROVA ◽  
Anna A. TSYNAEVA
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Pressure Gradient ◽  
Heat Exchangers ◽  
Numerical Study ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Longitudinal Pressure Gradient ◽  
Heat Transfer Coeffi

This paper is presented the numerical study of local heat transfer in the turbulent boundary layer with longitudinal pressure gradient. The study is based to free software with open source code (Salome and Code_Saturne) has been based by RANS approach and empirical models of turbulence. Validation of mathematical models and software is based by collation numerical results with the results of experimental study of fl ow characteristics in a turbulent boundary layer of longitudinal pressure gradient and high turbulence intensity (Epik E. Ya., NASc of Ukraine). The validation had a high qualitative coincidence of the fl ow characteristics determined as a result of the simulation with experimental data. We designed two constructive schemes of heat exchangers for air. This study presents a calculation plan for these heat exchangers. Results of the study are showed that the use of gradient heat exchange intensifi ers leads to an increase in the heat transfer coeffi cient from air to 17 %.

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