Kazuhide Mizobata

Numerical and Experimental Investigations on the Mach 2 Pseudo-Shock Wave in a Square Duct

This paper describes numerical and experimental investigations for the multiple shock wave/turbulent boundary layer interaction in a Mach 2 supersonic square duct. The numerical simulation is carried out with the Harten-Yee second-order accuracy TVD scheme and the Baldwin-Lomax turbulence model. The flow conditions are a free-stream Mach number ofM∞≈=2.0 and a Reynolds number ofRe∞;=2.5×107 and the flow confinements are δ∞/h=0.15 (case A) and δ∞/h=0.25 (case B), respectively. The computational results for both cases show good agreement with the experimental results. Based on these agreements, the flow quantities, which are very difficult to obtain experimentally, are analyzed by numerical simulation. Moreover, the effect of flow confinement on the pseudo-shock wave characteristics is also presented.

Correlation between Fluctuations of Mass Flux and Hydrogen Concentration in Supersonic Mixing

An experiment was carried out to confirm the validity of time series evaluation of supersonic mixing condition by using catalytic reaction on a platinum wire. Gaseous hydrogen was injected into supersonic free-stream (M1≈1.81) from injector. Time series condition of supersonic mixing was evaluated by using W-type probe which has a platinum wire and reference wire (nickel wire). The evaluation was done by simultaneously measuring each electric power supplied by each electric circuit which kept the temperature of wire constant. Specifically supplied electric power to Pt wire depended on catalytic heat release rate (giving hydrogen concentration) and flow convection. Meanwhile that to Ni wire depended on flow convection. The result showed that correlation coefficient between these electric powers increased when mixing developed. Investigations were also conducted for helium, air and no secondary injectant cases to compare with the hydrogen injectant case. The results indicated that it was possible to measure the time-series behavior of airhydrogen supersonic mixing layer or coherent motion of turbulence by using this evaluation.

Dynamic Characteristics of a Check Valve for Drain Pumps

Check valves for checking reverse water flows in drainage systems sometimes make large impacts through their sudden closure caused by accidental cutoff of drain pumps. In order to characterize such phenomena and to find design criteria for impactless check valves, we observed the motion of a check valve and measured its impact acceleration and pressures in the drainage pipe, using a subscale drainage system. Two peaks of impact acceleration were observed; The first one seemed due to collision of the check valve and the valve seat, whereas the second one did due to water column separation and recombination caused by the low pressure during the contact of the valve with the seat. The former can be reduced by adding mass to the check valve and by setting an appropriate valve-seat angle. The latter possibly can be reduced by relaxing the low pressure during the contact. Subsequently, the check valve opened through the water-column recombination impacts.Copyright

Numerical and experimental study of the Mach 2 pseudo-shock wave in a supersonic duct

This paper presents an investigation on the structure and characteristics of the multiple shock wave/turbulent boundary layer interaction in a Mach 2 supersonic square duct by numerical simulation and experiment. The numerical simulation is carried out with the Harten-Yee’s second-order accuracy TVD scheme and the Baldwin- Lomax’s turbulence model. The flow conditions are: free stream Mach number M∞ = 2.0, unit Reynolds number Re∞/m = 2.5xl07m−1, and the flow confinement is δ∞/h = 0.25. Good agreements between the numerical analysis and the experiment for the shape of the shock train and wall pressure distribution along the duct are obtained. Based on these agreements, the flow quantities, which are difficult to obtain by experiment, are analyzed by numerical simulation.

Development of a Small-scale Supersonic Flight Experiment Vehicle as a Flying Test Bed

With the aims of creating and validating innovative fundamental technologies for highspeed atmospheric flights, a small scale supersonic experiment vehicle is designed as a flying test bed. Several aerodynamic configurations are proposed and analyzed by wind tunnel tests. A twin-engine configuration is selected as the baseline. Its flight capability is predicted by point mass analysis on the basis of aerodynamic characterization and propulsion performance estimation. In addition, a prototype vehicle with the equivalent configuration and dimension is designed and fabricated for verification of the subsonic flight characteristics of the experiment vehicle. Its first flight test is carried out and good flight capability is demonstrated.

Shock wave propagation and bubble collapse in liquids containing gas bubbles

The large-amplitude shock wave propagation phenomena in air-bubble/ water mixtures were investigated using a two-phase shock tube. Effects of incident shock wave strength and initial void fraction on shock wave pressure characteristics were investigated exp erimentally. The frequency characteristic of large-amplitude shock wave pressure was clarified by the joint time-frequency analysis of shock wave pressure histories. Behavior of the bubbles collapsing behind large-amplitude shock waves was also clarified by pressure history measurements and high speed photography.

Off-design Performance of Turbojet Engine for Sub-scale Supersonic Unmanned Plane

The preliminary analysis is conducted for a turbojet engine of the Supersonic Unmanned Plane with a single spool, a convergence nozzle, a pitot intake and an afterburner. The error matrix method is employed, in which the compression ratio at the compressor, turbine inlet temperature and turbine expansion ratio are selected as independent variables for turbojet operation, then evaluated the three error vector components. The error vector is composed of the flow rate balance at compressor and turbine inlets, the compressor-turbine power balance, and pressure-mass flow rate balance at nozzle throat. To obtain solutions, the norm of error vector must be reduced to very small value by Newton iterative procedure. In the present study, compressor inlet diameter, turbine inlet temperature (TIT) limit are 0.14m, 1273K, respectively. The present engine models are operational along the constant flight dynamic pressure path of 50 kPa in transonic region ( Mach 0.9 to 1.3 ) The present study is focused on the effects of compression ratio and air flow rate at compressor on thrust level and the feasibility to break the sound barrier. For the feasibility study, the aerodynamic configuration of aircraft is proposed and its aerodynamic characteristic is also evaluated. Then, the possibility to break the sound barrier is discussed by comparing the thrust to the drag.

Characteristics of Bio-Ethanol Fueled GG-cycle Air Turbo Ramjet Engine for Supersonic UAV along Flight Trajectory

The flight experiment project of the subscale supersonic Unmanned Aerial Plane (UAV) is proceeding at Muroran Institute of Technology, Japan. For this UAV, the Gas-Generator Cycle Air Turbo Ramjet (GG-ATR) Engine is considered as its propulsion engine. For a successful flight, thrust margin and density-Isp play significant roles in a transonic and supersonic flight. In the present study, thermodynamic analysis of GG-ATR engine is conducted for 4 fuels ( Liquefied hydrogen, Liquefied Natural Gas, Ethanol and n-C12H26 ) with LOX oxidizer to seek the most favorable fuel for supersonic flight. Moreover, the feasibility study is also conducted by the flight trajectory analysis using the results of thermodynamic analysis of GG-ATR engine. It is indicated that supersonic flight with Mach 2.0 would be possible for the present engine and vehicle specifications.

Development Study on a Small-scale Supersonic Flight Experiment Vehicle with Air-breathing Propulsion

In order to incubate and support flight demonstration activities for prospective establishment of space planes, development of a small-scale supersonic unmanned airplane with turbojet propulsion is planned and is being carried out by collaboration between universities and JAXA. The Aerospace Plane Research Center (APReC) has been established in Muroran Institute of Technology for management and achievement of the development project. A small-scale turbojet engine concept is designed and its performance is evaluated preliminarily by a gasdynamical cycle analysis. A winged vehicle configuration is also designed. Its flight performance is predicted by three-degree-of-freedom trajectory analysis.