The effect of bulk viscosity on air has been studied by solving Navier-Stokes equations numerically. Bulk viscosity can only appear for both compressible and viscous fluid, and has been often ignored partly because it is neglectable for monatomic gases. However, coefficients of bulk viscosity of polyatomic gases such as air are not always negligible small in the process of rapid dilatation. Hence, the shifts in physical quantities between isentropic flow and bulk-viscous one are presented in this paper about a supersonic cylindrical source and a subsonic one.
Propulsive force is considered of a twodimensional airfoil executing a non-steady out-ofplane motion from a standpoint of the theorem of momentum in the framework of the linear theory. By regarding the system of the airfoil and wake as a superposition of vortex pairs, it is shown that, for a harmonically oscillating airfoil, an appropriate form of the wake vortex sheet to give the correct propulsion is one that is determined under the influence of the upwash of the airfoil only. Concerning the time mean of the propulsion of the oscillating airfoil, this approach is shown to be equivalent to the method for calculating the drag force of a cylindrical body using the Karman vortex street.
A computer program which is capable of computing performance of a fixed geometry two dimensional extemal compression supersonic inlet installed in a ramjet engine which satisfies the required air mass flow rate for the engine to operate at off design condition, was developed. The program can calculate quantity of possible air flow which may income through the inlet under the critical operation that is state of operation such as normal shock wave stands on the throat position of the air inlet, and required air flow for the engine which the ramjet engine requires to generate combustion gas that is exhausted through a jet nozzle of the engine under given engine operating condition and critical air inlet operation. When possible air flow exceeds required one, possible air flow decreases down to required one by subcritical operation. When possible air flow is less than required one, a pressure recovery factor of the air inlet is lower down till required air flow decreases down and equal to possible one by supercritical operation. It was found that influence of the inlet/nozzle characteristics on the position, i.e. the strength, of the normal shock wave is very sensitive. In particular, in supercritical regime where a ramjet engine is considered to stably operate, the pressure losses due to the normal shock wave becomes predominant compared to all the other losses, such as due to the oblique shock waves, combustor and nozzle. Thus, the characteristics significantly affect the global engine performance. Useful correlation for predicting the pressure recovery in super critical regime was also found from the numerical results, which is an exponential function of the flight and design Mach numbers and gas propenies. The correlation gave a good agreement with the available experimental data of an actual ramjet engine.
The fiber reinforced composites made by use of the filament-winding technique is useful for convex pressure vessels because of their many advantages such as high specific tensile strength etc. In the past developments, the netting analysis was an analytical tool for theoretical analysis of filament-wound pressure vessels. However, it has been difficult to predict analytically the burst strength after initial failure in pressure vessels which have arbitrary dome shapes with variable thickness and fiber orientation along meridian coordinate. In the present paper, the finite element method is used to analyse the mechanical characteristics of FW pressure vessel under internal pressure and to predict its burst pressure. The analysis takes into account the bending moment together with stretch-bending coupling effect, non-linear stress-strain relations and finite deflection. It is done by proposing the two initial failure criteria for laminae and the two ultimate fracture criteria for laminated structures. In analysing the ultimate strength, normal moduli transverse to fibers and shear moduli along fibers are assumed to become negative in parabolic functions during unloading after initial failure. The numerical results were obtained by applying the load incremental method to the isotensoid CFRP pressure vessel which was used for the kick-motor case (EXOS-KM-B) to launch the scientific satellite "Zikiken" and they were found to agree fairly with the experimental burst pressure and fracture behaviors.
The effects of addition of nitramine compound to a double-base propellant on the combustion efficiency were investigated. HMX was used as a nitramine compound. Reaction time in the dark zone, heat of explosion, and gaseous combustion products were measured. It was found that the reaction time in the dark zone and the pressure dependence of the heat of explosion were decreased by the addition of HMX. The reason for these facts is that the addition of HMX accelerates the reduction reaction of NO to N2 in the combustion wave. Consequently, the combustion efficiency of doublebase propellant is increased by the addition of HMX.
Computational figures of airplane surface are made to catch an airplane shape in the sence of sight. The airplane surface is described with a large number of quadrangles which are based on section lines of the airplane. In one concrete example, the section lines of an airplane model are measured. This airplane model is composed of a body, a wing, a tail unit and two jet engine nacelles. Several figures of the airplane model in various point of vision are drawn by using the law of perspective. These figures give us clear information of the Shape of the airplane model.