This paper will examine the applicability of the National Aeronautics and Space Administration (NASA) standard breakup model 2000 revision to explosion breakup in space. The cylinder specimens of stainless steel with smooth were explosively expanded to fragmentation. The driver was a column of the high explosive PETN inserted into the central bore and initiated by exploding a bundle of fine copper wires using a discharge current from a high-voltage capacitor bank. Expansion rate and the collection fragments will be analyzed based on the method used in the NASA standard breakup model 2000 revision to be compared with the explosion model adopted in the NASA standard breakup model. And this paper evaluated NASA standard breakup model 2000 revision model about size distribution, average cross-section area, area mass ratio distribution, delta velocity distribution.
In the present study, a dynamics model of an inflow-drive valve for pulse detonation engines (PDEs) is proposed, in which system the inflow of the valve periodically drives the valve piston. Since the inflow-drive valve needs no energy source to drive the piston, the mass flow rate divided by the valve mass is relatively large, and the response time for the mass-flow-rate change can be short. Moreover, the inflow-state condition for the stable valve operation is not restricted. The two-cylinder three-fluid type inflow-drive valve was fabricated. The maximum mass flow rate for one valve was evaluated as 6.3g/s, in which system the mass of the piston, the spring constant, and the supplied pressure were 3.8kg, 9800N, and 1.0MPa, respectively. The total mass flow rate using propellant was evaluated as 12g/s. The PDE system was constructed by using these inflow-drive valves. This system was stably operated in the frequency of 17.52Hz.
Effects of nozzle scale, total temperature, and an afterburner on jet noise characteristics from a pre-cooled turbojet engine are investigated experimentally. In JAXA (Japan Aerospace Exploration Agency), a pre-cooled turbojet engine for an HST (Hypersonic transport) is under development. In the present study, 1.0%- and 2.4%-scaled models of the rectangular plug nozzle (Nozzles I and II) are manufactured, and the jet noise characteristics are investigated under a wide range of total temperatures. For Nozzle I, no air-heater is utilized and the total temperature is 290K. For Nozzle II, a pebble heater and an afterburner (AB) are utilized upstream of the nozzle model, and the total temperature is varied from 520K (pebble heater) to 1540K (pebble heater + AB). The total pressure is set at 0.27 and 0.30MPa(a) for both nozzle models. Jet noise is measured using a high-frequency microphone set at 135 deg from the engine inlet, and normalized jet noise spectra are obtained based on AUjn law and Helmholtz number. For cases without afterburner, the normalized spectra agrees well regardless of the nozzle scale and total temperature where the velocity index lies from n = 7.7 to 9.2, and the correlation factor between the two facilities is shown to be about 1dB. For the case with afterburner, the normalized spectrum does not agree with other conditions where the velocity index n seems to be about 4.
This paper reports the analytical results of the influences of solid rocket and liquid rocket exhausts on ozone layer. It is worried about that the exhausts from solid propellant rockets cause the ozone depletion in the ozone layer. Some researchers try to develop the analytical model of ozone depletion by rocket exhausts to understand its physical phenomena and to find the effective design of rocket to minimize its effect. However, these models do not include the exhausts from liquid rocket although there are many cases to use solid rocket boosters with a liquid rocket at the same time in practical situations. We constructed combined analytical model include the solid rocket exhausts and liquid rocket exhausts to analyze their effects. From the analytical results, we find that the exhausts from liquid rocket suppress the ozone depletion by solid rocket exhausts.
Mixing and spreading characteristics of an orifice free jet are investigated changing the orifice plate thickness t/do, where do is the nozzle exit diameter, ranged from 0.01 to 1.5. Schlieren images show high mixing and spreading performances at t/do = 0.5 and Reynolds number Re = 1.5×104 because at the t/do = 0.5 the jet fluctuates by the separated flow from the inner edge of orifice alternates attachment and detachment to the outer edge. Hot-wire anemometry measurements are also performed to investigate the mean and fluctuating velocity profiles. It is found that the jet potential core length is insensitive to Re at Re > 7.0 × 103, but significantly influenced by the orifice plate thickness. The potential core length for t/do = 0.5 is the shortest reflecting the fluctuation at the nozzle exit.
In recent years Micro Air Vehicles (MAV) for disaster aerial video are developed vigorously. In order to improve aerodynamic performance of MAV wing performance in low Reynolds numbers (Re) need to be improved, but research on the theme are very rare. In category of Hand Launch Glider, a kind of model aircraft, glide performance are competed, as a result high performance airfoils in Re is around 20,000 are developed. Therefore for MAV's aerodynamic performance improvement airfoils of Hand Launch Gliders should be referred and aerodynamic characteristics of the airfoils desired to be studied. So in this research, aerodynamic characteristics of the gliders are measured in wind tunnel. And also consistency between wind tunnel test and glide test in calm air is examined to confirm reliability of wind tunnel test. Comparison of different airfoils and flow visualization are also performed.