Full-Coverage Discrete Hole Wall Cooling: Discharge Coefficients

1984 ◽  
Vol 106 (1) ◽  
pp. 183-192 ◽  
Author(s):  
G. E. Andrews ◽  
M. C. Mkpadi
Keyword(s):  
Heat Transfer ◽  
Pressure Loss ◽  
Small Diameter ◽  
Operating Regime ◽  
Coolant Temperature ◽  
Outlet Temperature ◽  
Discharge Coefficients ◽  
Full Coverage ◽  
Impingement Plate ◽  
Physical Features

Factors influencing the design of full coverage drilled plate wall cooling systems for gas turbine combustors are studied. It is shown that the large number of small diameter holes required result in a low Reynolds number operating regime. The physical features giving rise to the hole pressure loss are examined, and it is shown that under hot conditions heat transfer within the hole can appreciably alter the hole mass flow for a fixed pressure loss. It is shown that this effect may be used to estimate the hole outlet temperature and the results show that the heat transfer within the combustor wall may be very significant. The rise in coolant temperature within the wall appreciably alters the blowing rate and hence influences the hot gas side convective heat transfer to the plate. The influence of an impingement plate on hole discharge coefficients is also investigated and shown to be small.

scholarly journals Full Coverage Discrete Hole Wall Cooling: Cooling Effectiveness

1984 ◽  
Author(s):  
G. E. Andrews ◽  
M. L. Gupta ◽  
M. C. Mkpadi
Keyword(s):  
Heat Transfer ◽  
Low Temperature ◽  
Film Cooling ◽  
Test Facility ◽  
Coolant Temperature ◽  
Transfer Coefficients ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Full Coverage ◽  
Hole Wall

The development of a test facility for investigating full coverage discrete hole wall cooling for gas turbine combustion chamber wall cooling is described. A low temperature test condition of 750K mainstream temperature and 300K coolant temperature was used to investigate the influence of coolant flow rate at a constant cross flow Mach number. Practical combustion conditions of 2100K combustor temperature and 700K coolant temperature are investigated to establish the validity of applying the low temperature results to practical conditions. For both situations a heat balance programme, taking into account the heat transfer within the wall was used to compute the film heat transfer coefficients. The mixing of the coolant air with the mainstream gases was studied through boundary layer temperature and CO2 profiles. It was shown that entrainment of hot flame gases between the injection holes resulted in a very low ‘adiabatic’ film cooling effectiveness.

scholarly journals Full Coverage Discrete Hole Film Cooling: Investigation of the Effect of Variable Density Ratio (Part II)

1997 ◽  
Author(s):  
F. Bazdidi-Tehrani ◽  
G. E. Andrews
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Density Ratio ◽  
Design Parameters ◽  
Coolant Temperature ◽  
Hot Gas ◽  
Full Coverage ◽  
Film Heat Transfer

Experimental results of the corrective film heat transfer coefficient at the hot gas-side of the wall for full coverage discrete hole film cooling are presented for a range of practical geometries. The results are reported for various hot gas mainstream-to-coolant temperature (density) ratios, in the realistic range of 1.0–3.2. For combustor wall and turbine blades film cooling applications, the corrective film heat transfer coefficient was influenced significantly by the design parameters. It decreased with an increase in the number of holes per unit wall surface area, over the range of 4306–26910 m−2 and with an increase in the hole size, in the range of 1.0–2.2 mm, due to the improvement in film cooling. This was supported by the overall cooling effectiveness results, as reported previously (Bazdidi-Tehrani and Andrews 1994). A comparison between the two approaches for the prediction of the convective film heat transfer coefficient was made. It showed that the higher wall overall heat transfer, obtained using the present measurements of the wall overall heat transfer coefficient, resulted in a considerably higher film heat transfer coefficient than that predicted using the summation of the hole approach surface correlation of Sparrow (1982) and the internal hole correlation of Mills (1962). The variation of the mainstream-to-coolant temperature ratio did not establish consistent trends for various configurations and its effect on the film cooling performance was shown to be small.

INFLUENCE OF HEAT TREATMENT OF MOUNTAIN MASSIVE ON TEMPERATURE MODE OF GEOTHERMAL CIRCULATION SYSTEM

2018 ◽  
pp. 44-50
Author(s):  
Yu. P. Morozov
Keyword(s):  
Heat Transfer ◽  
Operating Time ◽  
Fluid Motion ◽  
Coolant Temperature ◽  
Circulation System ◽  
Thermal Processes ◽  
Temperature Mode ◽  
Heat Influx ◽  
Stationary Heat Transfer

Based on the solution of the problem of non-stationary heat transfer during fluid motion in underground permeable layers, dependence was obtained to determine the operating time of the geothermal circulation system in the regime of constant and falling temperatures. It has been established that for a thickness of the layer H <4 m, the influence of heat influxes at = 0.99 and = 0.5 is practically the same, but for a thickness of the layer H> 5 m, the influence of heat inflows depends significantly on temperature. At a thickness of the permeable formation H> 20 m, the heat transfer at = 0.99 has virtually no effect on the thermal processes in the permeable formation, but at = 0.5 the heat influx, depending on the speed of movement, can be from 50 to 90%. Only at H> 50 m, the effect of heat influx significantly decreases and amounts, depending on the filtration rate, from 50 to 10%. The thermal effect of the rock mass with its thickness of more than 10 m, the distance between the discharge circuit and operation, as well as the speed of the coolant have almost no effect on the determination of the operating time of the GCS in constant temperature mode. During operation of the GCS at a dimensionless coolant temperature = 0.5, the velocity of the coolant is significant. With an increase in the speed of the coolant in two times, the error changes by 1.5 times.

An Experimental and Numerical Study of Heat Transfer and Pressure Loss in a Rectangular Channel With V-Shaped Ribs

2006 ◽  
Author(s):  
Michael Maurer ◽  
Jens von Wolfersdorf ◽  
Michael Gritsch
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Thermal Performance ◽  
Pressure Loss ◽  
Numerical Study ◽  
Rectangular Channel ◽  
Reynolds Numbers ◽  
Transfer Enhancement ◽  
High Reynolds Numbers ◽  
High Reynolds

An experimental and numerical study was conducted to determine the thermal performance of V-shaped ribs in a rectangular channel with an aspect ratio of 2:1. Local heat transfer coefficients were measured using the steady state thermochromic liquid crystal technique. Periodic pressure losses were obtained with pressure taps along the smooth channel sidewall. Reynolds numbers from 95,000 to 500,000 were investigated with V-shaped ribs located on one side or on both sides of the test channel. The rib height-to-hydraulic diameter ratios (e/Dh) were 0.0625 and 0.02, and the rib pitch-to-height ratio (P/e) was 10. In addition, all test cases were investigated numerically. The commercial software FLUENT™ was used with a two-layer k-ε turbulence model. Numerically and experimentally obtained data were compared. It was determined that the heat transfer enhancement based on the heat transfer of a smooth wall levels off for Reynolds numbers over 200,000. The introduction of a second ribbed sidewall slightly increased the heat transfer enhancement whereas the pressure penalty was approximately doubled. Diminishing the rib height at high Reynolds numbers had the disadvantage of a slightly decreased heat transfer enhancement, but benefits in a significantly reduced pressure loss. At high Reynolds numbers small-scale ribs in a one-sided ribbed channel were shown to have the best thermal performance.

scholarly journals Investigation of binary chemical reaction in magnetohydrodynamic nanofluid flow with double stratification

2021 ◽  
Vol 13 (5) ◽  
pp. 168781402110162
Author(s):  
Aisha Anjum ◽  
Sadaf Masood ◽  
Muhammad Farooq ◽  
Naila Rafiq ◽  
Muhammad Yousaf Malik
Keyword(s):  
Heat Transfer ◽  
Differential Equations ◽  
Hartmann Number ◽  
Concentration Field ◽  
Double Stratification ◽  
Nanofluid Flow ◽  
Homotopy Analysis ◽  
Flow Heat ◽  
Chemically Reactive Species ◽  
Physical Features

This article addresses MHD nanofluid flow induced by stretched surface. Heat transport features are elaborated by implementing double diffusive stratification. Chemically reactive species is implemented in order to explore the properties of nanofluid through Brownian motion and thermophoresis. Activation energy concept is utilized for nano liquid. Further zero mass flux is assumed at the sheet’s surface for better and high accuracy of the out-turn. Trasnformations are used to reconstruct the partial differential equations into ordinary differential equations. Homotopy analysis method is utilized to obtain the solution. Physical features like flow, heat and mass are elaborated through graphs. Thermal stratified parameter reduces the temperature as well as concentration profile. Also decay in concentration field is noticed for larger reaction rate parameter. Both temperature and concentration grows for Thermophoresis parameter. To check the heat transfer rate, graphical exposition of Nusselt number are also discussed and interpret. It is noticed that amount of heat transfer decreases with the increment in Hartmann number. Numerical results shows that drag force increased for enlarged Hartmann number.

Sign in / Sign up

Export Citation Format

Share Document