Closure to “Discussion of ‘Flow and Heat Transfer in Ducts of Arbitrary Shape With Arbitrary Thermal Boundary Conditions’” (1966, ASME J. Heat Transfer, 88, p. 358)

1966 ◽  
Vol 88 (4) ◽  
pp. 358-358
Author(s):  
E. M. Sparrow ◽  
A. Haji-Sheikh
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Arbitrary Shape ◽  
Thermal Boundary Conditions ◽  
Flow And Heat Transfer

Flow and Heat Transfer in Ducts of Arbitrary Shape With Arbitrary Thermal Boundary Conditions

1966 ◽  
Vol 88 (4) ◽  
pp. 351-357 ◽  
Author(s):  
E. M. Sparrow ◽  
A. Haji-Sheikh
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Cross Section ◽  
Arbitrary Cross Section ◽  
Space Technology ◽  
Closed Form Solutions ◽  
Thermal Boundary Conditions ◽  
Flow And Heat Transfer ◽  
Temperature Distributions ◽  
Circular Segment

A computation-oriented method of analysis is presented for determining closed-form solutions for fully developed laminar flow and heat transfer in ducts of arbitrary cross section. The analytical method can accommodate both uniform and circumferentially varying thermal boundary conditions. The solutions provide information for local quantities such as the velocity and the temperature distributions as well as for overall quantities such as the friction factor and the Nusselt number. As an application of the method, solutions are presented for flow and for heat transfer in ducts of circular-segment cross section, a configuration that is of current interest in space technology.

Experimental Evidence of Temperature Ratio Effect on Turbine Blade Tip Heat Transfer

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
H. Jiang ◽  
Q. Zhang ◽  
L. He ◽  
S. Lu ◽  
L. Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Boundary Conditions ◽  
Transfer Coefficient ◽  
Experimental Evidence ◽  
Turbine Blade ◽  
Tip Clearance ◽  
Temperature Ratio ◽  
Thermal Boundary Conditions ◽  
Thermal Measurements

Determination of a scalable Nusselt number (based on “adiabatic heat transfer coefficient”) has been the primary objective of the most existing heat transfer experimental studies. Based on the assumption that the wall thermal boundary conditions do not affect the flow field, the thermal measurements were mostly carried out at near adiabatic condition without matching the engine realistic wall-to-gas temperature ratio (TR). Recent numerical studies raised a question on the validity of this conventional practice in some applications, especially for turbine blade. Due to the relatively low thermal inertia of the over-tip-leakage (OTL) flow within the thin clearance, the fluids' transport properties vary greatly with different wall thermal boundary conditions and the two-way coupling between OTL aerodynamics and heat transfer cannot be neglected. The issue could become more severe when the gas turbine manufacturers are making effort to achieve much tighter clearance. However, there has been no experimental evidence to back up these numerical findings. In this study, transient thermal measurements were conducted in a high-temperature linear cascade rig for a range of tip clearance ratio (G/S) (0.3%, 0.4%, 0.6%, and 1%). Surface temperature history was captured by infrared thermography at a range of wall-to-gas TRs. Heat transfer coefficient (HTC) distributions were obtained based on a conventional data processing technique. The profound influence of tip surface thermal boundary condition on heat transfer and OTL flow was revealed by the first-of-its-kind experimental data obtained in the present experimental study.

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