Oxyacetylene converging detonations are produced using a disk-type vessel of 80cm i.d. which consists of a converging and a diverging sections divided by a diffraction disk. The diverging section is preceded by a pre-run tube. Effects of pre-run tubes on the stability of convergence of detonations are examined. It is found that at initial pressures below 150 Torr, pre-run tubes are necessary in order to obtain stable cylindrical converging detonations. Utilizing a preliminary experimental apparatus with two-dimensional curved channels, the features of diffraction of detonations are observed by means of open.shutter and schlieren photographs. Recovery to the planarity of detonation front after passing through the curved path is found to take relatively long time. The propagation velocity measurement of detonation in the converging section shows that with decreasing radius of the converging wave, it behaves as the cylindrical converging shock wave of the similarity exponent n=0.85. The average pressure measured in the vicinity of the collapsing center of detonation is about 53kg/cmcm2 which nearly equals to 16 times the calculated pressure value of the C-J detonation under identical initial conditions, i.e., the initial pressure 60 Torr and the equimolar oxyacetylene gas mixture. This is close to the value 18 measured by LEE et al. at the initial pressure 190 Torr, using the same mixture.
Theoretical and experimental investigations are performed for Clβ of unswept flat (no dihedral) wings in sideslip. Theoretical investigations involve Vortex Lattice Methods and a sort of Slender Wing Theory. The Vortex Lattice Methods are applied in two forms; the one is Frozen Lattice Method (FL Method) and the other is Streamwise Lattice Method (SL Method). FL Method and Slender Wing Theory give generally good results and SL Method gives good results for elliptic wings, but not so for rectangular wings. The experiments give ClβCL for rectangular and elliptic wings of aspect ratio 2, 3, 5, 7, and show vortically separated flows on upstream side edge of sideslipping wings. Thus it may be probable that the reasonable analysis should take account of such vortically separated flows.
In the present paper, the finite element method is applied to the calculation of steady incompressible potential flow around a three-dimensional lifting body like an aircraft. The MORINO's formulation is modified in such a way that the lift acting not only on the wing, but also on the body is taken into account for a wing-body configuration. The problem is formulated in a form of an integral equation for the disturbance velocity potential on the body surface. By the use of the finite element method combined with the collocation method, this integral equation is reduced to a set of linear algebraic equations. The present method has been applied to obtaining the pressure distribution acting on the following three-dimensional lifting bodies: a tapered wing, ⊥-wing, _??_-wing, a cross wing with or without a fillet, and a wing-body configuration. The results obtained by the present method have been found to be in good agreements with those obtained by wind tunnel experiments. It has been also found that the aerodynamic interference effect can be well predicted by the use of the present method.
An analysis is presented for local radiation equilibrium temperatures in a semigray, nondiffuse conical cavity. The nondiffuse character is taken into account with a specular component of reflection. A simple rule is found to exist among the paths of specularly reflected rays in the cavity. Using this rule, the radiant interchange factors are easily obtained. The kernel of the integral equation for radiant flux takes infinitely large values at the apex. This behavior of the kernel is expressed with the delta function, so that the radiant heat exchange and temperature at the apex can exactly be obtained. The temperature calculated showed to be increased by the specular component of reflection in the short wave range but decreased by that in the long wave range, when the solar absorptance of the surface is large. A general conclusion on the property of the radiosity integral equation is obtained that its kernel takes infinitely large values at an intersection of more than two surfaces as at the apex and this singularity can be expressed in terms of the delta function.
Considering temperature dependency of the material properties of CFRP-UD composites, macroscopic thermal residual stresses of filament wound (FW) CFRP induced in the curing process are calculated as the first step. After evaluating these residual stresses, initial failure strengths of CFRP-FW materials are obtained based on three types of basic strength theories, i.e., Maximum stress theory, HOFFMAN theory and TSAI-WU theory. Curing conditions have considerable effect on the temperature dependency of the material properties and, as a result, on the thermal residual stresses. An important result is that proper combinations of loads and winding angles for helical FW-cylinder specimens are found in order to determine the key parameter in TSAI-WU theory, F12. From experimental results by others, it can be concluded that the minimum permissible F12 is suitable for this CFRP, contrary to the recommendation in the original paper by TSAI and WU. Thermal residual stresses have significant influence on the failure strengths. In most cases, failure strengths on the safest side are given by TSAI-WU theory using minimum F12.