Leading Edge Effect Research Articles

Natural convection around a semi-infinite vertical plate: Higher-order effects

On the basis of the first two terms in the boundary-layer expansion, it is shown by means of a global energy-rate balance that the leading-edge effect upon the total heat-transfer rate is given by a 1 kΔT where a 1 has the value 0·625 at a Prandtl number of 0·72. As a result, the average Nusselt number for the semi-infinite plate is given by (for σ = 0·72): N ̄ = 0·476G 1 4 + 0·625 + O(G − 1 12 ) (1) where the O(G− 1 12 ) term is indeterminate, arising from the appearance of an eigenfunction in the boundary-layer expansion. Direct comparison of (1) with experimental data is precluded by the necessity of first determining finite-plate effects which, on the basis of recent analyses of the trailing-edge region for the forced-flow problem, are expected to contribute a term of O(G 1 16 ) to (1).

Leading edge effects on the nusselt number for a vertical plate in free convection

Leading edge effects on the nusselt number for a vertical plate in free convection

Effect of inclination on laminar film condensation

The effect of inclination on laminar film condensation over and under isothermal flat plates is investigated analytically. The complete set of Navier Stokes equations in two dimensions is considered. Analysed as a perturbation problem, the zero-order perturbation represents the boundary layer equations. First and second order perturbations are solved to bring about the leading edge effects. Corresponding velocity and temperature profiles are presented. The results show decrease in heat transfer with larger ∥inclinations∥ from the vertical. Comparison with experimental data of Gerstmann and Griffith indicates a closer agreement of the present results than the analytical results of the same authors.

An Experimental Study of Vigorous Transient Natural Convection

External natural convection transient response leading to transition and established turbulent flow is determined experimentally and compared with the laminar double-integral theory predictions for processes wherein all transient effects are important. The theory is shown to give very accurate predictions during the laminar portion of the transient, and temperature overshool is not observed experimentally. In addition, several unexpected and very interesting observations were made concerning the stability of the flow as it proceeds to turbulence. The first main observation is that the propagating leading edge effect serves as a very effective moving boundary layer trip and triggers the resulting turbulence. Also for the less extreme condition (less vigorous transient) there is a relaminarization of the boundary layer. Explanations of these observations are proposed in the light of recently acquired results of linear stability theory analysis for small disturbances.

Comment on "Angle of Attack and Leading Edge Effects on the Flow about a Flat Plate at Mach Number 18"

Comment on "Angle of Attack and Leading Edge Effects on the Flow about a Flat Plate at Mach Number 18"

Angle of attack and leading edge effects on the flow about a flat plate at Mach number 18.

Data concerning viscosity and bluntness-induced pressures on a flat plate at angle of attack are presented for the strong interaction regime. Values of the hypersonic viscous interaction parameter x vary between 25 and 50. Pitot probe surveys have been made to determine the shock-wave location. Both positive and negative angles of attack were considered and incidence was varied from — 6° to 9°. Leading edge Reynolds number extends over the range from 70 to 1500. The flat plate is water cooled and the corresponding ratio of wall-to-stagnation temperature is about 0.21. Results are compared with existing theoretical models.

The Leading Edge Effect in Transient Natural Convection From a Vertical Plate

The Leading Edge Effect in Transient Natural Convection From a Vertical Plate

Laminar free convection along a vertical plate at extremely small grashof numbers

Laminar free convection in the vicinity of an isothermal vertical finite plate is studied in the Grashof-number range between zero and unity and two Prandtl numbers of 0.72 and 10.0, by means of a perturbation analysis. Solutions to the governing differential equations are expressed in perturbation series with the Grashof number itself taken as the perturbation parameter. Three terms in all series expansions have been calculated numerically by using the relaxation technique for both Prandtl numbers. Results of all perturbation functions, as well as of isothermal and stream lines for various Grashof numbers and the two Prandtl numbers are shown graphically and discussed. Finally, these results are used to discuss the leading-edge effects relative to the well-known boundary-layer solutions.

Viscous and Leading-Edge Effects in Hypersonic Flow

T PURPOSE of this note is to call attention to correlations of existing experimental data on hypersonic viscous and inviscid leading-edge effects by means of parameters proposed by general similitude considerations. The pressure similitude, according to references 1 and 2, for the hypersonic flow about a two-dimensional* blunt leading-edge slender body may be written (for a perfect gas with constant specific heats):