Temperature measurements in a hypersonic gun tunnel using heat-transfer methods

1967 ◽  
Vol 27 (3) ◽  
pp. 503-512 ◽  
Author(s):  
B. E. Edney
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Mach Number ◽  
Heat Losses ◽  
Transfer Rates ◽  
Gun Barrel ◽  
Compression Cycle ◽  
Initial Shock ◽  
Working Section ◽  
Good Agreement

The theory of Fay & Riddell (1958) is used to calculate stagnation temperatures from stagnation-point heat-transfer rates measured in the working section of a hypersonic gun tunnel at a Mach number of 9·8. Measurements using both thin-film gauges and calorimeters are described. The temperatures measured using this technique are found to be lower than predicted by Lemcke (1962) from measurements of shock strengths and final pressures in the gun barrel. This discrepancy is attributed to heat losses in the barrel during the initial shock compression cycle. A simple theory is developed to take into account these losses. There is good agreement between this theory and the experimental results.

Numerical Simulation of Natural Convection in Stationary and Rotating Cavities

2004 ◽  
Author(s):  
Zixiang Sun ◽  
Alistair Kifoil ◽  
John W. Chew ◽  
Nicholas J. Hills
Keyword(s):  
Heat Transfer ◽  
Centrifugal Force ◽  
Large Scale ◽  
Transfer Rates ◽  
Buoyancy Driven Flows ◽  
Gravity Driven ◽  
Gravity Driven Flow ◽  
Large Scale Flow ◽  
Rayleigh Numbers ◽  
Good Agreement

In compressor inter-disc cavities with a central axial throughflow it is known that the flow and heat transfer is strongly affected by buoyancy in the centrifugal force field. As a step towards developing CFD methods for such flows, buoyancy-driven flows under gravity in a closed cube and under centrifugal force in a sealed rotating annulus have been studied. Numerical simulations are compared with the experimental results of Kirkpatrick and Bohn (1986) and Bohn et al (1993). Two different CFD codes have been used and are shown to agree for the stationary cube problem. Unsteady simulations for the stationary cube show good agreement with measurements of heat transfer, temperature fluctuations, and velocity fluctuations for Rayleigh numbers up to 2 × 1010. Similar simulations for the rotating annulus also show good agreement with measured heat transfer rates. The CFD results confirm Bohn et al’s results, showing reduced heat transfer and a different Rayleigh number dependency compared to gravity-driven flow. Large scale flow structures are found to occur, at all Rayleigh numbers considered.

Effects of the Heat Transfer at the Side Walls on Natural Convection in Cavities

1990 ◽  
Vol 112 (2) ◽  
pp. 370-378 ◽  
Author(s):  
Y. Le Peutrec ◽  
G. Lauriat
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Thermal Conductance ◽  
Fluid Flows ◽  
Heat Losses ◽  
Transfer Rates ◽  
Side Walls ◽  
The Difference

Numerical solutions are obtained for fluid flows and heat transfer rates for three-dimensional natural convection in rectangular enclosures. The effects of heat losses at the conducting side walls are investigated. The problem is related to the design of cavities suitable for visualizing the flow field. The computations cover Rayleigh numbers from 103 to 107 and the thermal conductance of side walls ranging from adiabatic to commonly used glazed walls. The effect of the difference between the ambient temperature and the average temperature of the two isothermal walls is discussed for both air and water-filled enclosures. The results reported in the paper allow quantitative evaluations of the effects of heat losses to the surroundings, which are important considerations in the design of a test cell.

Experimental and Numerical Study of Evaporative Heat Transfer From Ten- Micro Microchannels

2006 ◽  
Author(s):  
Hoki Lee ◽  
T. A. Quy ◽  
C. D. Richards ◽  
D. F. Bahr ◽  
R. F. Richards
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Latent Heat ◽  
Numerical Study ◽  
Electrical Power ◽  
Three Dimensional ◽  
Working Fluid ◽  
Silicon Membrane ◽  
Transfer Rates ◽  
Evaporative Heat Transfer

Experimental and numerical results are presented for evaporative heat transfer from ten-micron square open-top channels. The radial channels are fabricated in epoxy photoresist on a two micron thick silicon membrane. The working fluid is pumped by capillary forces from a reservoir at the edge of the silicon membrane into the channels where it evaporates. The electrical power dissipated in a thin-film heater in the center of the membrane, the conduction heat transfer rate radially out of the membrane, and the rate of evaporation of the working fluid are measured. A three-dimensional finite difference, time-domain integration is used to predict sensible and latent heat transfer rates. Only 5-10% of the energy dissipated as heat in the thin film heater is carried away as latent heat by the evaporating working fluid. Computed temperatures and heat transfer rates are shown to match the experimental results.

A Mathematical Model For Steady Operation of Stirling-Type Engines

1968 ◽  
Vol 90 (1) ◽  
pp. 45-50 ◽  
Author(s):  
E. B. Qvale ◽  
J. L. Smith
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Mathematical Model ◽  
Heat Exchangers ◽  
Correction Factors ◽  
Transfer Rates ◽  
Flow Friction ◽  
Independent Variables ◽  
Basic Performance ◽  
Good Agreement

A mathematical model of Stirling-type engines has been developed. The complexity of the problem has been reduced by analyzing the various components of the engine (heat exchangers, regenerator, and cylinders) separately for cyclically steady conditions, and by selecting pressure, temperature, and mass as the independent variables. The required piston displacements are a computed result. Losses due to flow friction, piston blow-by, and finite heat transfer rates have been accounted for by applying correction factors to the basic performance which is computed without these effects. The theory has been carried out for engines, but it is equally valid for refrigerators with minor modification. The theory is in good agreement with available experimental data.

High-Temperature Thermocouple and Heat Flux Gauge Using a Unique Thin Film-Hardware Hot Junction

1985 ◽  
Vol 107 (4) ◽  
pp. 938-944 ◽  
Author(s):  
C. H. Liebert ◽  
R. Holanda ◽  
S. A. Hippensteele ◽  
C. A. Andracchio
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Flux ◽  
High Temperature ◽  
High Heat ◽  
High Heat Flux ◽  
Transfer Experiment ◽  
Plate Heat ◽  
Good Agreement

A special thin film-hardware material thermocouple (TC) and heat flux gauge concept for a reasonably high-temperature and high heat flux, flat-plate heat transfer experiment was fabricated and tested to gauge temperatures of 911 K. This unique concept was developed for minimal disturbance of boundary layer temperature and flow over the plates and minimal disturbance of heat flux through the plates. Comparison of special heat flux gauge Stanton number output at steady-state conditions with benchmark literature data was good and agreement was within a calculated uncertainty of the measurement system. Also, good agreement of special TC and standard TC outputs was obtained and the results are encouraging. Oxidation of thin film thermoelements was a primary failure mode after about 5 hr of operation.

Heat and Mass Transfer in the Corner Flow Region of Vertical Microgrooves

2010 ◽  
Author(s):  
Xuelei Nie ◽  
Xuegong Hu ◽  
Suresh V. Garimella ◽  
Dawei Tang
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Evaporation Rate ◽  
Flow Region ◽  
High Heat ◽  
Maximum Amount ◽  
Force Balance ◽  
Transfer Rates ◽  
Corner Flow ◽  
High Heat Transfer

Evaporation of the thin film formed in microgrooves is associated with high heat transfer rates. One of the factors that limits this heat transfer is the capacity of the microgroove to drive fluid into the thin film. The mass flow rate and mass flux in the corner flow region of a microgroove is experimentally and theoretically investigated in this work. The experiments yield the speed at which wetting occurs in vertical microgrooves. The wetting speed reflects the balance between the gravitational, viscous and capillary forces acting on the film. A force balance is also conducted on the liquid in the corner flow region of the microgrooves. This analysis allows a calculation of the maximum amount of liquid that the microgrooves can drive to the evaporating surface in the corner flow region, which in turn determines the maximum evaporation rate in this localized area.

Flow Field Measurements in a Cold Flow Annular Sector Turbine Cascade Test Facility and an Annular Sector Cascade Test Facility Operating at Near-Engine Conditions

2001 ◽  
Author(s):  
S.-H. Wiers ◽  
T. H. Fransson ◽  
U. Rådeklint ◽  
M. Annerfeldt
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Mach Number ◽  
Flow Field ◽  
Three Dimensional ◽  
Test Facility ◽  
Turbine Cascade ◽  
Cold Flow ◽  
Annular Sector ◽  
Good Agreement

Aerodynamic investigations in a cold flow annular sector high-pressure turbine cascade test facility and an annular sector cascade facility operating at near-engine conditions are presented. The test section of both facilities is a 36° sector cascade of a modern turbine stator consisting of 6 vanes. The two facilities have been designed in order to gain detailed information concerning film cooled gas turbine vanes. Due to the operation conditions of the hot annular sector cascade it takes over the part of detailed investigations of the influence of film cooling on the heat transfer. In the cold annular sector cascade facility investigations on the aerodynamic behavior of the cascade are performed. Both facilities together will lead to a better understanding of the complicate three-dimensional flow in modern gas turbines. A detailed description of both facilities is given in this paper. Aerodynamic investigations in both facilities were performed. The in- and outlet Mach number and profile Mach number distribution is in good agreement in both of them and shows a periodic flow filed. Aerodynamic performance measurements in the cold flow facility have been conducted by means of a five-hole pneumatic pressure probe traverses 106% of cax downstream of the cascade to gain information about the quality of the flow field across flow passages “+1” and “–1” in terms of yaw angle, pitch angle and primary loss distribution. Comparison with a three dimensional Navier Stokes solvers show a very good agreement with the measurements. In order to deduce the external heat transfer coefficient on the vane a transient test procedure was adopted in the high-pressure hot facility. The dependency of the heat transfer coefficients on the Reynolds number is presented in the paper. The experimental results show reasonable agreement with calculations using a two dimensional boundary layer code.

Sign in / Sign up

Export Citation Format

Share Document