Ryojiro Minato

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.

EFFECT OF HYDROGEN JET POSITION RELATIVE TO PLASMA TORCH ON SUPERSONIC COMBUSTION

ABSTRUCT The purposes of the present study were to clarify the three-dimensional structure of hydrogen flame reinforced by a plasma torch and to analyze the effect of the position of a hydrogen jet relative to the plasma torch on the combustion characteristics. Results of the present analysis clarify that the combustion efficiency of hydrogen jet injection into the upper stream of the plasma torch becomes larger than that of hydrogen jet injection into the lower stream. When the hydrogen jet is injected into the lower stream of the plasma torch, the combustion efficiency is reduced with the increase of the interval between the plasma torch and the hydrogen jet. In addition, as the interval decreases, an extension of the recirculation zone, which causes a significant increase of combustion efficiency, is observed. On the other hand, when the hydrogen jet is injected into the upper stream of the plasma torch, a larger interval generally results in larger combustion efficiency. When the plasma torch is injected with high injection pressure, penetration of the plasma torch is extended and mixing of hydrogen and air is significantly improved, resulting in higher combustion efficiency.

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.

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.