Effect Of Yaw Research Articles

Missile and spacecraft coning instabilities

Abstract : The destabilizing effect of yaw or Magnus-type moments on the angle-of-attack behavior of spinning missiles is well known to the missile designer. Yaw moments can also have a destabilizing (or stabilizing) effect on the attitude or coning motion of spinning spacecraft. The analogy might not be readily apparent because of the difference between the angle of attack of a spinning missile in atmospheric flight and the coning angle of spin-stabilized spacecraft. A concise treatment of the dynamics associated with coning instabilities is presented, and illustrative examples of classical missile and spacecraft coning instabilities are reviewed.

Heat transfer, pressure drop, and fluid flow patterns in yawed tube banks

Complementary heat transfer, pressure distribution, and flow visualization experiments were performed to investigate the effect of yaw on both staggered and in-line tube tanks. The heat transfer measurements were carried out on a row-by-row basis, and pressures were measured internal to the tube banks as well as upstream and downstream. Air was the heat transfer fluid. The visualization experiments revealed that yaw markedly affected the manner in which the flow impinged on the tubes of the in-line array, with a lesser effect of yaw on the flow field in the staggered array. At a given freestream Reynolds number, the Nusselt number generally decreased as the angle of yaw increased. The yaw effect was well correlated for the staggered array, but not so well for the in-line array because of the aforementioned flow field modifications. The in-line-array Nusselt numbers generally exceeded those for the staggered array, a trend which was accentuated at larger yaw. The pressure drop decreased with increasing yaw. In the present operating range, the in-line-array pressure drops were smaller than the corresponding staggered-array values.

Effect of yaw on forced convection heat transfer from a circular cylinder

Wind tunnel experiments encompassing ten angles of yaw between 0 (crossflow) and 60° yielded Nusselt numbers extending over the range of free stream Reynolds numbers from 9000 to 70,000. Supplementary experiments were also performed in which the heating pattern at the surface of the cylinder was varied and in which major alterations were made in the boundary layer on the wind tunnel wall. These experiments established that the measured Nusselt numbers were truly representative of the uniform wall temperature boundary condition and were independent of the characteristics of the wind tunnel boundary layer. It was found that as the cylinder was yawed relative to the crossflow orientation, the Nusselt number at first decreased, attained a minimum at a yaw angle of 15°, and then increased to a broad maximum which occurred in the range of yaw angles between 30 and 45°. Thereafter, the Nusselt number decreased with increasing yaw. Furthermore, the data did not obey the so-called Independence Principle, according to which the Nusselt number is supposed to be a unique function of the Reynolds number based on the component of the free stream velocity normal to the cylinder. As a further supplement to the heat transfer experiments, the pattern of fluid flow adjacent to the cylinder surface was visualized by means of the oil-lampblack technique.

Effect of Yaw on Heat Transfer in a Cuplike Cavity Facing a Freestream Flow

Wind tunnel experiments were performed to determine the response of the heat transfer coefficient at the base of an open-ended cylindrical cavity to yawed (i.e., nonperpendicular) impingement of the freestream flow on the cavity opening. The experiments encompassed yaw angles from 0 (perpendicular impingement) to 45 deg, cavity depth–diameter ratios from 0 to 0.65, and Reynolds numbers from 4500 to 45,000. In the absence of yaw, very large reductions of the base surface transfer coefficient were brought about by increases of cavity depth. When the freestream flow is yawed relative to the cavity opening the coefficient rebounds from its low no-yaw values, with the rebound being accentuated for large yaw, deep cavities, and high Reynolds numbers. Notwithstanding the rebound, the resulting base surface heat transfer coefficients are lower than those for the no-yaw, zero-depth cavity. Operating conditions are identified for which reductions of the transfer coefficient of 50 percent or more are encountered. On this basis, cavities and recesses appear to be an effective means for reducing heat loss.

Some observations of the transition process on the windward face of a long yawed cylinder

An experiment has been performed to determine the effect of yaw upon transition in the boundary layer formed on the windward face of a long cylinder. The china-clay-evaporation and surface-oil-flow techniques have been used to study the development of the fixed-wavelength stationary disturbances which are characteristic of cross-flow instability. It has been found that the boundary layer is also susceptible to time-dependent disturbances which grow to very large amplitudes prior to the onset of transition. These disturbances have been studied with a hot-wire anemometer. The conditions necessary for the onset and completion of transition have been determined by the use of surface Pitot tubes. Data from the experiment have been compared with the simple criteria for instability and transition which were proposed by Owen & Randall over thirty years ago. In general it has been found that these criteria are inadequate, and, where possible, improvements have been proposed. The raw data are presented in sufficient detail for them to be used to test, or calibrate, future theoretical models of the transition process in three-dimensional boundary-layer flows.

Effect of yaw on supersonic and hypersonic flow over delta wings

The problem of a delta wing in a high speed stream has been approached using linearised potential flow theory for low supersonic Mach number, and using thin shock layer theory for hypersonic Mach number. Recently the author has given a new theory of supersonic and hypersonic flows with attached shock wave over the compression surface of an unyawed delta wing. It has the advantage of being unified for both supersonic and hypersonic flows, and it gives almost identical results compared with exact numerical solutions. The purpose of this note is to extend the theory of Ref. 4 to include the effects of yaw.

Effect of yaw of repose on ballistic match of similar projectiles

Effect of yaw of repose on ballistic match of similar projectiles

Flutter of simply supported, parallelogrammic, flat panels in supersonic flow.

The flutter problem of uniform, thin, isotropic, parallelogrammic, flat panels acted upon by in-plane loads and simply supported on all edges is formulated in oblique coordinates, based on the classical small-deflection, thin-plate theory. For the aerodynamic loading, the two-dimensional static approximation is used in the first instance including the effect of yaw of the panel. Approximate analysis is made by using Lagrange's equations employing double Fourier sine series in oblique coordinates to represent the deflection surface. Numerical calculations for the critical dynamic pressure have been made first for unstressed panels for different combinations of side ratio, angle of skew, and angle of yaw. The majority of the calculations were made using 16 terms in the series. A detailed examination of convergence is made for a few typical cases. It is found that the critical dynamic pressure increases monotonically with the angle of skew for side ratios (ratio of length to width) of 1 and 2, whereas for side ratio 0.5 it decreases initially and then begins to increase.

Similar Solution of a Laminar Boundary Layer with Rotational Free Stream

T NOTE is a summary of a study of the effect of small angles of yaw on boundary-layer development on a cone including turbulent boundary-layer data previously obtained in connection with a more general experimental program. 3 Details of the experiments are given in references 1 and 2. In Fig. 1 the effect of yaw on the laminar velocity boundary layer on the windward side of a cone is presented. I t can be seen that at the meridianal plane as the angle of yaw increases the boundary layer thins and the velocity gradient becomes steeper. On the leeward meridianal plane (Fig. 2), however, the effect is markedly to increase the thickness of the boundary layer and even to change the apparent character of the boundary layer from laminar to turbulent. This effect has occurred already as the angle of attack is changed from zero to 1.2° as shown in the figure. By plotting the shape parameter for these apparently turbulent boundary-layer profiles for comparison with other profiles which were taken from the normally turbulent boundary layer at zero yaw, it was found that the shape parameters thus determined fell together with normal turbulent boundary-layer shape parameters. Therefore, one inclines to the belief that normal turbulent

Wind Tunnel Tests on Seven Aerovanes

Each of the Aerovanes used on the 420‐ft meteorology tower at Brookhaven has been tested in one or more wind tunnels. An equation of motion is defined. Comparisons are offered in terms of the period of each instrument and its damping coefficient. Other comparisons include starting speeds, stopping speeds, and the effects of aging and unbalance on the performance of Aerovane propellers.The effect of yaw on the readings of windmill‐type anemometers has been investigated further. An expression is given for the relationship between true speed, indicated speed, and angular displacement.The recovery time of an Aerovane propeller from rest can be expressed as a hyperbolic function of speed.

Effect of yaw on vane anemometers

Effect of yaw on vane anemometers