MEASUREMENT OF HEAT TRANSFER RATE TO TURBINE BLADES AND NOZZLE GUIDE VANES IN A TRANSIENT CASCADE

1978 ◽  
Author(s):  
T. V. Jones ◽  
D. L. Schultz ◽  
M. L. G. Oldfield ◽  
L. C. Daniels
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Turbine Blades ◽  
Guide Vanes ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes

scholarly journals Heat Transfer to Rotating Turbine Blades in a Flow Undisturbed by Wakes

1994 ◽  
Author(s):  
T. Garside ◽  
R. W. Moss ◽  
R. W. Ainsworth ◽  
S. N. Dancer ◽  
M. G. Rose
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbine Blades ◽  
Heat Fluxes ◽  
Reverse Direction ◽  
Similar Data ◽  
Blade Surface ◽  
Guide Vanes ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes

The flow over the high pressure blades of a gas turbine is disturbed by wakes and shock waves from the nozzle guide vanes upstream. These disturbances lead to increased heat transfer to the blade surfaces, the accurate prediction of which is an essential stage in the design process. The Oxford Rotor experiment consists of a highly instrumented 0.5 m diameter shroudless turbine which is supplied with air from a piston tube during the 200 ms run time and simulates realistic engine Mach and Reynolds numbers. Previous experiments have measured blade surface pressures and heat transfer rates, and compared them with similar data from linear cascades. The present work is designed to enable the accuracy of rotation terms in computational fluid dynamics (CFD) calculations to be assessed, by providing heat transfer data from the rotating frame in the absence of wakes. Flow disturbances were avoided by removing the nozzle guide vanes, the correct angle of incidence onto the rotor blades being achieved by rotating the rotor in the reverse direction. Blade surface heat fluxes were measured using thin film gauges. In the absence of the usual blade-passing fluctuations, the root-mean-square fluctuation in heat flux was typically only 7% of the DC level. Nusselt numbers are compared with cascade data and CFD predictions from both a three-dimensional viscous Navier-Stokes equation solver and a two-dimensional boundary layer prediction. The low inlet turbulence level produced a long laminar region on the suction surface followed by sudden transition. CFD predictions of Nusselt number on this surface were very sensitive to the choice of boundary layer state, and the experimental level was approximately mid-way between predictions with a transitional intermittency distribution and those with a turbulent distribution. On the pressure surface the levels were approximately 25% below predicted levels, and possible reasons for this are considered.

Film Cooling Research on the Endwall of a Turbine Nozzle Guide Vane in a Short Duration Annular Cascade: Part 1—Experimental Technique and Results

1992 ◽  
Vol 114 (4) ◽  
pp. 734-740 ◽  
Author(s):  
S. P. Harasgama ◽  
C. D. Burton
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Guide Vane ◽  
Density Ratio ◽  
Suction Side ◽  
Coolant Temperature ◽  
Guide Vanes ◽  
Nozzle Guide ◽  
Annular Cascade ◽  
Nozzle Guide Vanes

Heat transfer and aerodynamic measurements have been made on the endwalls of an annular cascade of turbine nozzle guide vanes in the presence of film cooling. The results indicate that high levels of cooling effectiveness can be achieved on the endwalls of turbine nozzle guide vanes (NGV). The NGV were operated at the correct engine nondimensional conditions of Reynolds number, Mach number, gas-to-wall temperature ratio, and gas-to-coolant density ratio. The results show that the secondary flow and horseshoe vortex act on the coolant, which is convected toward the suction side of the NG V endwall passage. Consequently the coolant does not quite reach the pressure side/casing trailing edge, leading to diminished cooling in this region. Increasing the blowing rate from 0.52 to 1.1 results in significant reductions in heat transfer to the endwall. Similar trends are evident when the coolant temperature is reduced. Measured heat transfer rates indicate that over most of the endwall region the film cooling reduces the Nusselt number by 50 to 75 percent.

scholarly journals Endwall Heat Transfer and Aerodynamic Measurements in an Annular Cascade of Nozzle Guide Vanes

1995 ◽  
Author(s):  
M. C. Spencer ◽  
G. D. Lock ◽  
T. V. Jones ◽  
N. W. Harvey
Keyword(s):  
Heat Transfer ◽  
Mach Number ◽  
Reynolds Numbers ◽  
Flow Visualisation ◽  
Surface Shear ◽  
Guide Vanes ◽  
Nozzle Guide ◽  
Annular Cascade ◽  
Nozzle Guide Vanes ◽  
Transient Liquid Crystal Technique

Aerodynamic and heat transfer measurements have been made on the hub and casing endwalls of an annular cascade of high pressure nozzle guide vanes. The measurements have been made over a range of engine representative Mach and Reynolds numbers and with large levels of freestream turbulence intensity. The transient liquid crystal technique has been employed, which has the advantage of yielding full surface maps of heat transfer coefficient. Computational predictions and aerodynamic measurements of Mach number distributions on the endwall surfaces are also presented, along with surface-shear flow visualisation using oil and dye techniques. The heat transfer results are discussed and interpreted in terms of the secondary flow and Mach number patterns.

Film Cooling Research on the Endwall of a Turbine Nozzle Guide Vane in a Short Duration Annular Cascade: Part 1 — Experimental Technique and Results

1991 ◽  
Author(s):  
S. P. Harasgama ◽  
C. D. Burton
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Guide Vane ◽  
Density Ratio ◽  
Suction Side ◽  
Coolant Temperature ◽  
Guide Vanes ◽  
Nozzle Guide ◽  
Annular Cascade ◽  
Nozzle Guide Vanes

Heat transfer and aerodynamic measurements have been made on the endwalls of an annular cascade of turbine nozzle guide vanes in the presence of film cooling. The results indicate that high levels of cooling effectiveness can be achieved on the endwalls of turbine nozzle guide vanes (NGV). The NGV were operated at the correct engine non-dimensional conditions of Reynolds number, Mach number, gas-to-wall temperature ratio and gas-to-coolant density ratio. The results show that the secondary flow and horse-shoe vortex act on the coolant which is converted towards the suction side of the NGV endwall passage. Consequently the coolant does not quite reach the pressure side/casing trailing edge, leading to diminished cooling in this region. Increasing the blowing rate from 0.52 to 1.1 results in significant reductions in heat transfer to the endwall. Similar trends are evident when the coolant temperature is reduced. Measured heat transfer rates indicate that over most of the endwall region the film cooling reduces the Nusselt number by 50% to 75%.

scholarly journals Unsteady phenomena at the combustor-turbine interface

2021 ◽  
Vol 5 ◽  
pp. 202-215
Author(s):  
Faisal Shaikh ◽  
Budimir Rosic
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
High Speed ◽  
Guide Vane ◽  
Secondary Flows ◽  
Test Facility ◽  
Unsteady Heat Transfer ◽  
Guide Vanes ◽  
Nozzle Guide ◽  
Nozzle Guide Vanes

The combustor-turbine interface in a gas turbine is characterised by complex, highly unsteady flows. In a combined experimental and large eddy simulation (LES) study including realistic combustor geometry, the standard model of secondary flows in the nozzle guide vanes (NGV) is found to be oversimplified. A swirl core is created in the combustion chamber which convects into the first vane passages. Four main consequences of this are identified: variation in vane loading; unsteady heat transfer on vane surfaces; unsteadiness at the leading edge horseshoe vortex, and variation in the position of the passage vortex. These phenomena occur at relatively low frequencies, from 50–300 Hz. It seems likely that these unsteady phenomena result in non-optimal film cooling, and that by reducing unsteadiness designs with greater cooling efficiency could be achieved. Measurements were performed in a high speed test facility modelling a large industrial gas turbine with can combustors, including nozzle guide vanes and combustion chambers. Vane surfaces and endwalls of a nozzle guide vane were instrumented with 384 high speed thin film heat flux gauges, to measure unsteady heat transfer. The high resolution of measurements was such to allow direct visualisation in time of large scale turbulent structures over the endwalls and vane surfaces. A matching LES simulation was carried out in a domain matching experimental conditions including upstream swirl generators and transition duct. Data reduction allowed time-varying LES data to be recorded for several cycles of the unsteady phenomena observed. The combination of LES and experimental data allows physical explanation and visualisation of flow events.

Procedures for Determining Surface Heat Flux Using Thin Film Gages on a Coated Metal Model in a Transient Test Facility

1988 ◽  
Vol 110 (2) ◽  
pp. 242-250 ◽  
Author(s):  
J. E. Doorly
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Rate ◽  
Surface Heat Flux ◽  
Transfer Rate ◽  
Turbine Blades ◽  
Surface Heat ◽  
Test Facility ◽  
Coated Metal

The paper describes how thin film surface heat flux gages may be used to measure surface heat transfer rate to enamel-coated metal turbine blades. Flexible methods, which are also computationally efficient, for obtaining the heat transfer rate are described. Experimental results, using the new coated metal turbine blades and processing techniques, in a stationary transient cascade facility are given, and are shown to agree well with results using the existing method for gages on single-layer substrate blades. The application of the gages for measuring highly unsteady heat transfer is also discussed.

scholarly journals Effect of Uniform Magnetic Field on Melting at Various Rayleigh Numbers

2019 ◽  
Vol 3 (4) ◽  
pp. 263-273 ◽  
Author(s):  
Sumer Bharat Dirbude ◽  
Vivek Kumar Maurya
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Turbine Blades ◽  
Transverse Magnetic ◽  
Melting Rate ◽  
Industrial Applications ◽  
Rayleigh Numbers

Melting phenomena occurs in various industrial applications, such as metal castings of turbine blades, environmental engineering, PCM-based thermal storage devices, etc. During the design of these devices, they are designed for efficient heat transfer rate. To improve the heat transfer rate, understanding of the important flow processes during the melting (and solidification) is necessary. An objective of the present work is to study the effect of natural convection and magnetic field on interface morphology and thereby on melting rate. In this work, therefore, an effect of uniform transverse magnetic field on the melting inside a cavity, filled initially with solid gallium, at various Rayleigh numbers (Ra=3×105, 6×105, and 9×105) is presented. A 2D unsteady numerical simulation, with the enthalpy-porosity formulation, is performed using ANSYS-Fluent. The magnetic field is characterized by the Hartmann number (Ha) and the results are shown for the Ha = 0, 30 and 50. The horizontal walls of the cavity are considered insulated and vertical walls are respectively considered hot and cold. It is observed that the role of natural convection during the melting is significant on the temperature distribution and solid-liquid interface. The increased magnetic field (Ha = 30 and 50) found to have a suppressing effect on the dominance of natural convection at all Rayleigh numbers (Ra=3×105, 6×105, and 9×105).

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