Space inflatable structures must be deployed under stable conditions to maintain the deployment reliability. A simple deployment control method is required for lightweight and easily foldable inflatable structures. This paper deals with the deployment uniformity of inflatable tubes with folding crease patterns. The polygon foldings are proposed for simple folding method of inflatable tubes to deploy under the uniform condition. Two types of non-rigidizable inflatable tube with hexagonal and octagonal folding and four types of rigidizable inflatable tube with hexagonal folding are manufactured as the test articles. Surface condition of the rigidized membrane and accuracy of the inflatable tube after rididization completion are evaluated by observation and measurement. The deployment test is conducted under gravity condition to estimate the deployment uniformity of each folding method. It is clarified that the deployment uniformity of inflatable tubes with proposed polygon folding is within 5 to 6% from the deployment experiment.
Many kinds of observation techniques have been developed to obtain the properties of atmospheric conditions. The advanced observation techniques of the flow in relatively large scale are remote sensing by satellite facilities, long range observations by radar or Doppler Sodar, etc., while data from conventional climometers set at fixed places are merely limited information about local scale flow. Captive balloons are also available and feasible for the observation of local flows if their standing mechanics are robust against the strong wind and the motion of balloon are stable for all wind direction and the change of wind direction. In this paper, a compact captive balloon (about 2m diam.) for flow measurement is proposed and the preservation of balloon height level and the stabilization of its motion are challenged by using a kite. The relation between force balances acted on the balloon and the balloon height or position was estimated and confirmed in experiments. Although the lift force of single kite worked successfully, it is found that the performance of plural kites is less in the traction of balloon since the interaction of their tensions. The compact balloon supported by the kite enabled the over 300m floating by virtue of the small size causing only low air resistance.
Recently, formation flying of small satellites is recognized as an important future on-orbit technology. It has many potentials such as realizing unlimited aperture size for radio sensing missions or spontaneous sensing at multiple points, leading to flexibility of space mission, low cost, tolerance against single satellite failure, and easier system upgrade, etc. However, usually the member satellites should be kept in a coordinated way, which requires lots of fuel. The orbital control methods requiring little fuel consumption should be developed. This paper focuses on J2 perturbation as a disturbance to the formation keeping. First, it is made clear why the formation is dispersed under the J2 perturbation. And then two new methods to keep the formation on a low earth orbit with small fuel consumption are proposed which are evaluated in computer simulations.
A method to evaluate aerodynamic performances of scramjet engines by using multi-probe rakes was proposed. The aerodynamic tests were carried out under Mach 4 flight conditions. The Pitot and static pressures were measured at 250 points in the cross sectional area of the engine exit by the rakes. Local mass flux and thrust function were evaluated from the pressure measurement at each point and integrations of these values enabled to obtain the mass flow rate and the stream thrust at the engine exit. The air capture ratios were independently measured by the rakes and a conventional choked flowmeter. The air capture ratios measured by these two methods agreed within 2%. It was found that the rakes enabled to measure the air capture ratio more simply than the flowmeter. Additionally, the effect of boundary layer ingestion to an internal drag was investigated by the rakes. The decrease of air capture ratio measured by the rakes showed that the ingested boundary layers were separated in the inlet. The pressure drag of inlet increased by the separation and the pressure thrust decreased by the decrease of air capture ratio. As a result, the internal drag increased when the forebody boundary layer was ingested.
The entire flowfield in a segmented-constrictor type arc-heated wind tunnel is simulated to numerically characterize the freestream properties produced by the wind tunnel. The flow from the upstream electrode chamber to the nozzle throat is solved using a newly developed Navier-Stokes code named ARCFLO3 which accounts for Joule heating and radiative transfer phenomena in the arc heater, and the downstream region of the nozzle beyond the throat is described by thermochemical nonequilibrium Navier-Stokes equations using the flow properties at the nozzle throat obtained by the ARCFLO3 calculation as an inflow condition. The method is applied to calculate one operating condition in the 1MW arc-heated wind tunnel facility at ISAS. The calculated results are compared with the experimental data to show the validity of the present method.
Numerical prediction of the reservoir temperature in a shock tunnel is performed by simulating the unsteady flow field in the driven tube and nozzle of the shock tunnel of Nagoya University. The axisymmetric, compressible Navier-Stokes equations are numerically solved by a finite volume code with the third order MUSCL in space and the fourth order Runge-Kutta method in time. The results show that the flow pattern near the end of the driven tube is highly complicated, because the reflected shock wave interacts with the boundary layer and contact discontinuity. The present simulation estimates the reservoir temperature of the shock tunnel at a maximum value of 876K, which agrees with the value predicted from the heat flux experimentally measured at a model in the test section.