A control system of variable geometry mixed compression axisymmetric intake is experimentally studied at ONERA S3 supersonic wind tunnel. The acceleration/deceleration of the space plane is simulated by changing the free stream velocity. The intake is successfully controlled with 90% of the maximum total pressure recovery and mass capture ratio. In this experiment, two subjects about control of axisymmetric intake are also cleared. First, the effect of the trapping of the terminal shock by bleed holes causes the disturbances in the terminal shock control system. Second, a special compression form change operation is necessary when the intake compression form change from all external compression to mixed compression.
Satellite capturing is one of the most important and the most difficult task to provide on-orbit services. An appropriate role assignment of an on-board system and a ground station is important to design a system under the constraints of on-board computing power and communication time delay. This paper presents a design concept of autonomous satellite capturing system using a manipulator mounted satellite, together with the results of an space experiments using Engineering Test Satellite #7 (ETS-VII); a space robot designed by the concept.
Direct Simulation Monte Carlo (DSMC) method based on the Boltzmann equation, in-cooperating a new reactive inelastic molecular collision model, has been employed to analyze the fuel gas mixing in two-dimensional supersonic shear flow which originates from the meeting at a thin plate (lip) edge of two parallel flows, a supersonic air stream and a sonic hydrogen gas flow. In the present study, the influence of hydrogen gas temperature upon the mixing within the shear layer is clarified. In a companion paper (the 2nd report), the relationship between mixing and chemical reaction will be presented.
Following the 1st report, the present study treats the relationship between mixing and chemical reaction of hydrogen to reveal some details of the initial combustion process, when it is sonically injected parallel to the Mach 2.44 airstream from the thin plate (lip) edges of a 2-D nozzle. By applying a hydrogen-oxygen 16 reaction system, Direct Simulation Monte Carlo (DSMC) analysis clarifies the influences upon the initial combustion due to hydrogen temperature, which is the most significant, and the other factors like the hydrogen number density and the shear velocity. A need of some measures for enhancing such weak initial combustion is also addressed.
Thrust performance and stable operation conditions of an anode layer type Hall thruster was investigated using a 1.5kW class anode layer type Hall thruster. The thrust efficiency reached at 53% with the specific impulse of 2,000s, which are competitive with these of SPT-100 thrusters. Anode shape and axial position of the anode were changed. Stability of the discharge was found sensitive to the anode configuration and applied magnetic flux density.
The comprehensive kinetic model equation for unsteady one-dimensional flow is numerically solved to obtain a converging solution for a plane shock structure problem. This model equation is proposed by Oguchi on the basis of the Grad’s 13-moment approximation, and its collision term is expressed in an explicit function of the peculiar velocities. The problem is selected as a typical problem for surveying the applicability of the present model to gas dynamic problems. The numerical calculations are performed for Maxwell molecules. The free-stream Mach number range is from 1.05 to 2.0. The resultant shock wave profiles of the number density exhibit reasonable forms with monotonic change, and the resultant shock thickness values agree well with the corresponding Navier-Stokes values. The present results suggest us to open a way for the applicability of the present kinetic model to various gas dynamic problems in weakly rarefied conditions.
Numerical investigation of the rolling moment control of a delta wing using a micro-flap in supersonic flow is performed in the present study. So far, several experiments and CFD analyses regarding the micro-flap in subsonic flow have been reported, and the location of a leading edge separation vortex and its size are found to play a key role in producing the rolling moment. On the other hand, in supersonic flow, the mechanism of rolling moment generation is found to be different from that in subsonic flow. The leading edge separation vortex is not so much affected by micro-flap installation. However, a large pressure change behind the micro-flap is observed, which causes the rolling moment of the delta wing. Moreover, the rolling moment in the supersonic flow is generated only in one direction, unlike the subsonic flow, where it is produced in either direction.
Authors have been attempting to develop a multidisciplinary design optimization tool for a large-scale system using Genetic Algorithm (GA), and to apply this tool to the integrated optimization problem of the airframe design and its flight trajectory for an advanced space transportation vehicle that is a spaceplane. The results of the latest calculation for the problem above obtained by the developed tool showed that airframes (solutions) converged on four areas in the solution space and sensitivity of design variables of the airframe shape was remarkably different in each convergence area. Although high-ranking solutions having good value of the performance index have various airframe configurations, those flight trajectories hardly changed. The best solution showed that it is necessary to reduce the weights of airframe components and to improve the performance of air-breathing engine for realizing a feasible airframe size. It is suggested that this tool is absolutely useful for searching a solution at the conceptual designing phase of a spaceplane.
The present paper describes a one-dimensional model for a compressible internal flow with mass and heat additions in a constant area duct taking account of the upstream boundary layer. The conservation equations across a control volume are treated one-dimensionally by assuming an appropriate mean flow. This model can estimate the maximum amount of the mass flow rate on the flow choking for a given upstream free Mach number and boundary layer thickness. As the result, a parallel injection can add more amount of mass flow rate than normal injection in the present analytical condition. The characteristics of the flow such as the down stream Mach number, static pressure and total pressure distributions are analyzed with the boundary layer thickness for given upstream condition. Also, the analytical result of the present model shows better agreement with the previous experimental data on the mass and heat additional flows in constant area duct.