A new type of thin film heat transfer gauge is applied to the measurements of heat-transfer coefficients in the interaction regions of oblique shock waves and fully developed turbulent boundary layers. It has been developed for the measurements of heat flux with high spatial resolution and fast response for wind tunnels with long flow duration. Experiments have been performed under the conditions of Mach number=4, total pressure=1.2MPa, Tw/T0=0.59-0.65, Reynolds number=1.3-1.5×107, and incident shock angles from 17.8 degrees to 22.8 degrees. Flow fields are visualized by the Schlieren technique. Both distributions of surface pressure and heat-transfer coefficient are measured throughout the interaction regions by scanning the shock generator parallel to the free stream. Owing to the high spatial resolution of the new sensor, complicated features of the aerodynamic heating in the interaction regions are revealed.
A concept of PAR (Power Augmented Ram Wing) is presented. It will be useful in future for over-water transport vehicles to carry passengers, cargos, and/or cars. It is much faster than ships, while it requires no run-way in contrast to airplanes. The PAR concept makes the fuselage-shape “aero-configured” rather than “hydro-configured”, and so decreases the parasite-drag singificantly. An empirical formula is found for the effective aspect ratio which is applicable to verious kinds of Ground Effect Wings. The present PAR concept has a variable geometry wing, in front of which tiltable turboprop engines are installed. Untill the take-off speed is exceeded, the wing is swept-forward with extended full span flaps (the outer ones are differential flaps). In cruising condition the wing becomes unswept. If the sea-state is bad the vehicle can fly off-ground effect with unswept wing. Thus cancelling operations is much more reduced than hovercrafts or hydrofoil-boats. Special devices are proposed for the tip-floats, which improve aero-dynamic efficiency and which alleviate load due to wave-impacts.
To clarify the effects of wake contraction, swirl velocity and mutual interactions on the cruising performances of a counter rotating propellers ATP, fundamental analyses based on the generalized momentum theory were carried out. Assuming a linear interaction scheme, the optimum propulsion efficiency and the wake geometry which minimize the total induced losses for a given thrust were established as solutions of a calculus of variations problem. The optimum combinations of operating parameters such as the thrust sharing ratio, the power sharing ratio and the disc area ratio between top and bottom propellers were also specified and their dependency upon the axial velocity, the total thrust level and the axial spacing were revealed. It was understood that, in addition to the counter rotating effect of propellers, upwash effect of the contracted top propeller wake on the outer part of the bottom propeller disc play a fundamental role for improving the propulsion efficiency of a CR ATP.
This paper describes an experimental study of the interference of two spheres placed on a plane boundary. The experiment was carried out in an N. P. L. type wind-tunnel having a working section of 500mm×500mm×2000mm in size at Reynolds number 4.74×104. The surface-pressure distributions of two spheres at various relative positions were measured and the drag, lift and side-force coefficients were determined from the surface-pressure distributions. The experimental results were compared with those of a single sphere.