Kenya Harada

Firing Test of a Hypersonic Turbojet Engine Installed on a Flight Test Vehicle

Hypersonic turbojet engine with pre-cooling system is tested under sea level static condition. The engine is installed on a flight test vehicle, which will fly at Mach 2 speed by a free fall experiment from a stratospheric balloon. Liquid hydrogen fuel and gas hydrogen fuel is supplied to the engine from a tank and cylinders installed in the vehicle. Designated operation of major components of the engine is confirmed. Corrected rotation speed, corrected air flow rate and pressure ratio of the compressor is raised by pre-cooling with liquid hydrogen fuel. Corrected air flow rate and pressure ratio at the pre-cooling operation is reduced comparing from that without pre-cooling on the same corrected rotation speed. There is a deep temperature distortion at the inlet of the compressor and it may cause the performance reduction. Large amount of liquid hydrogen is supplied to the pre-cooler in order to obtain enough pre-cooling performance for Mach 5 flight. Then, fuel rich combustion at the after-burner is adopted. Cowl part of variable geometry nozzle is made with C/C composite material and it has no damage after the combustion test. Operation of the core engine by liquid hydrogen is attained by using a control valve with small effective diameter.

Development study on precooler for atrex engine

A review of the development of a precooler for the air-turboramjet expander cycle engine (ATREX) is given. Three types of precooler for the ATREX engine ground test model were designed, manufactured and tested under the sea level static condition. The results suggested two problems affecting the precooler performance such as heat transfer rate and air flow pressure drop. One is non-uniformity of the air flow through the tube banks. The other problem is frost formation on the heat transfer surfaces. Concerning the non-uniformity, the shell configuration was modified based on the analysis by CFD calculation. To improve the precooler performance under frosting condition, the new method to add a condensable gas into the air flow was proposed and.examined by experiments on a subscale heat exchanger model. Addition of a small quantity. of ethanol can be effectively restrain the decline of the precooler performance due to frost formation.

Mach 4 Wind Tunnel Experiment of Hypersonic Pre-Cooled Turbojet Engine

Pre-cooled turbojet engine is investigated to realize Mach 5 class hypersonic transport aircraft. The engine has been demonstrated under sea level static and Mach 2 flight conditions using hydrogen as fuel. Presently, Mach 5 propulsion wind tunnel test using liquid hydrogen is planned and the engine components such as pre-cooler, core engine, afterburner and exhaust nozzle are under development. The engine components were tested under Mach 4 simulating condition by connecting the pre-cooler inlet to an air supply facility. The engine was tested in a propulsion wind tunnel with Mach 4 flight condition. Liquid nitrogen was supplied to the pre-cooler as a coolant in place of liquid hydrogen. Gaseous hydrogen was supplied to the main burner to drive the turbine with the combustion gas. As a result, high temperature structure and cooling system was proved to endure Mach 4 high temperature airstream. Wind-mill starting sequence of the core engine under Mach 4 flight condition was confirmed. Gross thrust of the core engine was obtained as an initial evaluation of elemental performance.

Systems Analysis on Hypersonic Airplanes using Pre- Cooled Turbojet Engine

Systems analysis and evaluation of Mach 5 class hypersonic airplanes is performed. The airplane can fly across the Pacific Ocean in 2 hours. A multi-disciplinary optimization program with aerodynamic, thermal structure, propulsion and trajectory is used to define baseline shape. Pre-cooled turbojet engine is assumed as the propulsion system for the hypersonic airplane. The engine can be operated from takeoff to Mach 5, continuously. This engine has adopted pre-cooling cycle using cryogenic liquid hydrogen. The high temperature inlet air at the hypersonic flight will be cooled by liquid hydrogen for fuel. Surface flow of the airplane at hypersonic speed and low speed are evaluated using results of CFD analyses. The control characteristics with control wings and variation of aerodynamic characteristics by adding strakes are obtained by a low speed wind tunnel experiment. The heat flux distribution on the surface of the airframe at hypersonic cruise condition is evaluated by using the results of CFD analyses. The characteristics of heat shield materials for the surface of the fuselage at downstream of the exhaust gas is evaluated by an elemental experiment.

IMPROVEMENT OF PERFORMANCE OF THE PRECOOLED CYCLE ENGINE SPOILED BY ICING

The effectiveness of a method to improve the precooler performance under frosting condition was investigated by experiments on a sub-scale heat exchanger model. Addition of a methanol proved to be most effective compared with other possible substances in both cases of lower and higher cooling wall temperature than its melting point. Then the effectiveness of the methanol addition was ascertained for the practical condition that means the same tube configuration and flow velocity as the precooler designed for the ATREX engine firing test model. The result showed that the addition of the same quantity as the water vapor could restrain the frost layer from choking the flow in the duration of 300 seconds, which is sufficient time for precooler operation. The required methanol mass along the ATREX engine flight path was estimated to be less than 3 % of fuel hydrogen on board. Accordingly, the method came to be promising candidate for practical application.

Evaluation of detection capability of crustal movement by airborne SAR (PI-SAR-L2) repeat-pass interferometry

This paper reports the evaluation results of detection capability of crustal movement by an airborne SAR (Pi-SAR-L2) repeat-pass interferometry. Pi-SAR-L2 belongs to by JAXA (Japan Aerospace Exploration Agency). The object is to estimate the detection accuracy of crustal movement by Pi-SAR-L2.

Hypersonic Flight Experiment Plan of Pre-Cooled Turbojet Engine

,Hypersonic technology experimental vehicle for flight experiment of pre-cooled turbojet engine is investigated. The vehicle is assumed to mount two pre-cooled turbojet engines at the bottom. The vehicle will be accelerated up to Mach 5 flight speed by an external booster rocket. The vehicle aims at demonstrating Mach 5 cruise capability for a short period. Aerodynamic performance, engine thrust and structure mass are analyzed for the baseline system. Lift to drag ratio has improved by adding a strake in front of the main wing. Engine thrust is estimated without considering the additional thrust at the external nozzle. Structure mass is estimated using an optimization program using finite element method. Force balance around the vehicle is summarized and it is confirmed that the vehicle will slightly descend and decelerate at Mach 5 flight condition, without considering the external thrust. Component tests of pre-cooled turbojet engine with simulated flight condition are conducted toward the flight experiment. Pre-cooler is tested with high temperature condition simulating Mach 4 flight condition. Core engine starting sequence is confirmed with low pressure condition. Fuel supply system for hydrogen fuel with super-critical condition is tested to attain precise fuel flow control for the core engine. High temperature tests and propulsion wind tunnel tests of the engine with simulating Mach 5 condition is planned.