scispace - formally typeset
Search or ask a question

Showing papers by "Ephraim M Sparrow published in 1963"


Journal ArticleDOI
TL;DR: Radiant emission from diffuse conical cavity openings, including wall distribution of radiant emittance, heat flux, and temperature, was studied in this paper, where the authors presented a method to detect the presence of radiant emissions from conical cavities.
Abstract: Radiant emission from diffuse conical cavity openings, including wall distribution of radiant emittance, heat flux, and temperature

66 citations


Journal ArticleDOI
TL;DR: In this article, an analysis has been made to determine the reduction in stagnation point heat transfer when blowing and a magnetic field act simultaneously, and it is found that in the presence of blowing, the magnetic field may be considerably more effective in reducing heat transfer than in the no-blowing case.
Abstract: An analysis has been made to determine the reduction in stagnation point heat transfer when blowing and a magnetic field act simultaneously. It is found that in the presence of blowing, the magnetic field may be considerably more effective in reducing heat transfer than in the no-blowing case. The results show that the heat transfer reduction due to the simultaneous action of blowing and magnetic field is greater than that attained by multiplying together the separate reductions due to blowing alone and magnetic field alone. This favourable interaction diminishes as the Prandtl number diminishes and thus may be of lesser importance for highly ionized gases for which the Prandtl number is low. The analysis is carried through for both two- and three-dimensional stagnation points, and results are reported for Prandtl numbers of 0.01, 0.1, 0.7, 1, and 10.

35 citations


Journal ArticleDOI
TL;DR: An analysis of heat-generating laminar flow in a parallel-plate channel including both prescribed wall temperature and prescribed wall heat flux was carried out for both the thermal entrance region and the fully developed region as mentioned in this paper.
Abstract: An analysis of heat-generating laminar flow in a parallel-plate channel including both prescribed wall temperature and prescribed wall heat flux was carried out for both the thermal entrance region and the fully developed region. Consideration was given not only, to the basic cases of uniform wall temperature and uniform wall heat flux but also to arbitrary longitudinal distributions of the wall temperature or wall heat flux. The internal heat generatio in the fluid may also have arbitrary longitudinal and transverse variations. (P.C.H.)

31 citations


Journal ArticleDOI
TL;DR: In this article, the length of duct required to approach to within 5% of the fully developed pressure gradient was about 20 to 25 hydraulic diameters for annuli and a circular tube with interchangeable square or rounded entrance sections.
Abstract: Entrance-region studies, based on static-pressure measurements, were carried out with water flowing in annuli and a circular tube fitted with interchangeable square or rounded entrance sections. The tests covered the Reynolds number range from 16,000 to 70,000. For the annuli, the length of duct required to approach to within 5% of the fully developed pressure gradient was about 20 to 25 hydraulic diameters. This is in general accord with entrance length results for circular tubes and parallel-plate channels but differs from prior results for the annulus which had indicated entrance lengths larger by a factor of ten. The results for the sharp entrance showed a definite effect of separation and were characterized by high loss coefficients. For the rounded entrance, the initial part of the flow development was laminar; the entrance-region pressure drop did not substantially exceed (and in one case was less than) the corresponding fully developed pressure drop. Also for the rounded entrance, flow stability was improved and a monotonically decreasing pressure gradient obtained when a turbulent boundary layer was induced by means of a trip. Fully developed friction factors were calculated and compared with theory.

28 citations


Journal ArticleDOI
TL;DR: In this article, an analysis of turbulent heat transfer in a tube with a circumferentially-varying temperature or heat lux is presented, where the authors consider the case of a single tube.

22 citations


Journal ArticleDOI
TL;DR: Radiant energy absorption of a rectangular-groove cavity for both diffuse and specular reflector surfaces was studied in this paper, showing that the cavity can absorb energy from both specular and diffuse reflectors.
Abstract: Radiant energy absorption of a rectangular-groove cavity for both diffuse and specular reflector surfaces

16 citations



Journal ArticleDOI
TL;DR: In this article, an analysis of the fluid flow and heat transfer characteristics of a highly rarefied gas passing through a tapered tube or conical nozzle is presented, and the rate of mass throughflow has been determined as a function of the pressures and temperatures of the system and of the tube dimensions.
Abstract: An analysis is presented of the fluid flow and heat transfer characteristics of a highly rarefied gas passing through a tapered tube or conical nozzle. The rate of mass throughflow has been determined as a function of the pressures and temperatures of the system and of the tube dimensions. It is found that, at moderate and large angles of taper, the mass throughflow is affected little by increases in tube length, except for short tubes. At small taper angles, the mass throughflow is more sensitive to tube length. The energy transport analysis includes simultaneous convection and radiation. Numerical results have been found for the adiabatic wall temperature. It is found that, for surfaces that can be approximated realistically as diffuse emitters and reflectors of thermal radiation, the results differ little from those for pure radiation.

12 citations


Journal ArticleDOI
TL;DR: In this article, the heat transfer characteristics of a turbulent flow in a parallel-plate channel with uniform heat flux were analyzed by integration of the energy equation and were plotted on a Nusselt number vs Prandtl number graph for Reynolds numbers from 10/ sup 4/ to 5 x 10/sup 5/.

10 citations



Journal ArticleDOI
TL;DR: In this paper, a general analysis including arbitrary thermal boundary conditions has been made for the energy transport in a circular tube in which a highly rarefied gas is flowing, and it was found that at all temperature levels except those well below room temperature, the results corresponding to combined convective and radiative transport differ little from those for purely radiative.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the transfer of heat owing to simulataneous thermal radiation and free-molecule convection in a parallel-plate channel and found that the results for the combined convective-radiative transport differed little from those for a purely radiative transport.
Abstract: The flow of a highly rarefied gas in a parallel-plate channel and the transfer of heat owing to simulataneous thermal radiation and free-molecule convection has been investigated analytically. The analysis is facilitated by analogies which exist between the processes. The mass throughflow has been determined as a function of the temperatures and pressures of the system and of the channel dimensions. The heat transfer analysis is first carried out in general and then specialized to the boundary conditions of uniform wall temperature, uniform wall heat flux, and the adiabatic wall. It was found that at temperature levels corresponding to room temperature and above, the results for the combined convective-radiative transport differed little from those for a purely radiative transport.