Ryoji Yanagi

Analytical Study of Pre-Cooled Turbojet Engine for TSTO Spaceplane

Authors are investigating a concept of pre-cooled turbojet engine for Two-Stage-To-Orbit (TSTO) spaceplane. In this study, the engine system is designed with some assumptions. Technological problems and operational limits of the engine are clarified by an engine performance analysis. Then, flight performance of the engine is compared with some air-breathing engines such as: pre-cooled air turbo ramjet, turbo-ramjet and rocket-ramjet Sizes and mass of engines are estimated by analogical estimations with use of a database of existing engines. As a result, pre-cooled engines brought better payload performance than other engines.

Hypersonic Turbomachinery- Based Air-Breathing Engines for the Earth-to-Orbit Vehicle

Hypersonic air-breathing engines will make the Earth-to-orbit vehicle completely different from the present one powered by rocket engines. The space plane propelled by a certain hypersonic air-breathing propulsion system is expected to appear in the next century. The turbomachinery-based engine (turboengine) is a candidate for the space plane propulsion system and will be combined with scramjet and rocket engines. Turboengines, including turboramjet, air-turboramjet, and their modifications, may be applied as the accelerators to the space plane having a high specific impulse at a rather low supersonic Mach number. Here, a conceptual study of these turboengines with preliminary system design, performance calculations, and consideration of relative merits of the engine concepts is performed for the configuration, performance, weight, and size. An engine evaluation with mission capability of the space plane for assumed requirements is made. As a result, engine performance depends on the liquid oxygen utilization, and weight and size of the engine are important factors for application to the space plane. Thus a certain optimization of the engine system itself and of a combination of the engines would be necessary.

Simplified Analysis on Electromagnetic-Driving Fan for Aircraft Propulsion

An experimental and analytical investigation into a newly proposed electromagneticdriven fan concept is described. Environmental friendliness in aviation is a key feature in the development of future air-breathing engines, and a desirable technology to be introduced is an electromagnetic motion fan system, because it will tremendously reduce the total operating emission as well as reduce weight and increase maintainability increase energy efficiency compared to conventional aero engines. The proposed fan concept has a potential to fulfill the requirements for environmental compatibility and also possesses many other applications such as vector thrust operation. The present paper shows the results of the test on a concept verification model and the result revealed the importance of the controlling parameters to produce efficient power transmission. The accompanying analytical result further explains the motion mechanisms and gives suggestions for the novel design of the fan system.

Performance Analysis of a Fuel Cell Hybrid Aviation Propulsion System

So-called Blended Wing Body (BWB)-type aircraft can accommodate electric fan driven propulsion systems as propulsion devices, providing distributed propulsion. Our earlier report presented a motor concept that is suitable for driving propulsion fans for that aircraft configuration. This report describes an analytical model of a propulsion system power source with size based on the reference vehicle design presented previously by the authors. Take-off and in-flight conditions are presented. The combined fuel-cell and gas-turbine system shows different features in each case.

Performance Analysis of Fan-Driving Electric Motors in a Fuel-Cell Hybrid Powered Propulsion System for Aviation

So-called Blended Wing Body (BWB)-type aircraft can accommodate electric fan driven propulsion systems as propulsion devices, providing distributed propulsion. Our earlier report presented a motor concept that is suitable for driving propulsion fans for that aircraft configuration, and provided preliminary sizing of the fan and motor requirement to a given reference vehicle. This paper describes a numerical simulation model of a driving-fan motor with size based on the reference vehicle design the authors presented previously. Numerical simulation is applied first to existing experimental data of the present electric motor concept. Preliminary design and analysis of the motor are provided with dimensions of the 0.71-m-diameter class fan module to be applied to the distributed propulsion system installed in the reference vehicle. Numerical simulation shows that the originally proposed shape of the rotating coil is favorable for the designated purpose, suggesting the basic configuration of the motor driving system.

Preliminary Design Investigation of Electromagnetic Motors for Turbofan-Drive Assist

This paper describes the procedure and status of the preliminary design investigation of a motor-assisted turbofan propulsion system used for scheduled testing. The applied motor configuration was described earlier for use of turbo/hybrid electric propulsion device. Review of earlier research emphasized the potential of the motor configuration for motor motion assistance of a conventional and/or near future turbofan propulsor. Earlier studies showed the motor configuration’s potential for motor motion assistance of a conventional turbofan propulsor or one developed in the near future. The experiment plan uses a miniaturized turbofan engine model developed at JAXA to assess multi-variable model-based optimization control with an actual turbofan engine. The modification and preliminary design procedure and analytical results are then shown in order. In the context of numerical analysis, the present design motor is expected to be applicable as an independently powered assist measure for turbofan engine control. Finally, some perspectives are given of the potential of this motor configuration for use in multi-dimensional applications.

Internal flow field and mass flow rate of 2DCD ejector nozzles

One of the most promising exhaust nozzles for future super/hypersonic transports will be a nonaxisymmetric variable geometry nozzle and more than likely the ejector nozzle which introduces bleed/bypass air from the intake section in order to solve inlet/engine flow mismatch, cool nozzle walls, reduce external drags, and thus improve overall performance of the propulsion system. In the present study, cold flow tests with a scale model of a typical two-dimensional convergentdivergent (2DCD) ejector nozzle configuration have been carried out to investigate its internal flow field and aerodynamic performances such as mass flow ratio. An optical flow visualization method such as MachZehnder interferometry have been used. Shear layers, compression waves and equi-density contours hi the nozzle flow field are visualized. Two-dimensional CFD prediction has been carried out and compared with the test results. The agreement of the prediction with test results is fairy good. The parameters that determine mass flow rate of primary and secondary flow have been studied using the CFD method.

The Effect of the Bleed Hole Arrangement on Suppression of Swept Shock Wave/Turbulent Boundary Layer Interactions

The paper describes the experiments on the swept shock/boundary layer interactions with and without boundary layer bleed, as the fundamental research issue in the development of a supersonic air intake. The experiments were conducted in a supersonic wind tunnel with a cross section of 1 m by 1 m of the National Aerospace Laboratory. The emphasis was placed on understanding the flow structures of the interaction, using a shock generator with a 15 deg. wedge at Mach numbers of 3.25, 3.11 and 2.63. Attention was also focused on suppression of the interaction by a bleed system of hole arrangement. Three cases of the bleed system, where the bleed portions were located upstream, downstream, and in both regions of the swept shock wave, were employed. It was found by both Pitot-pressure rake and surface pressure survey methods, in addition to the vapor screen visualization technique, that the interaction becomes stronger with increasing Mach number. The arrangement of the bleed portion covering both upstream and downstream of the shock position is effective to suppress swept shock wave/boundary layer interactions.

Experimental Study of Mixed Compression Air-Intake for Hypersonic Airbreathing Engines

Supersonic air-intake for Mach number higher than 2.5 is being investigated with experimental, analytical and computa- tional methods. The study is performed in a part of the joint research program led by National Aerospace Laboratory (NAL) on the hypersonic airbreathing turbo-engines with subsonic ram combustion. The wind tunnel models are de- signed in two-dimensional mixed compression type with multi- shock system and tested in NALs Mach 4 supersonic wind tunnel. Pressure measurements and flow visualization by schlieren method, oil-flow and vapor screen techniques are being done. Here, the test results of Mach 4 and Mach 5 models are discussed. The Mach 4 model is fixed geometry with 5-shock system and the Mach 5 one is variable geometry with 6-shock and an isentropic compression surface. An expansion fore- plate was installed at the Mach 5 model inlet to accelerate the air-speed at the entry. The bleed systems at throat, ramp and cowl are adopted and evaluated in terms of pressure recovery and stability. Importance of establishment of the internal shock wave system, reduction of upstream Mach number of terminal shock wave and suppression of flow separation at diffusers are found. It is also found that ramp bleed is effective to confirm intake start and to minimize shock/boundary layer interaction.

Investigation on the Potential of Hybrid Aero-Engine System with Electromagnetic-Driving Fan

The so-called Blended Wing Body (BWB)-like aircraft configuration might accompany an electric fan driven propulsion system as a propulsion device. Electromagnetic fans are good for distributed propulsion. Our earlier paper presented a motor concept suited to driving propulsion fans for the aircraft configuration. By introducing a reference vehicle with hydrogen as the fuel, a system arrangement and other key technological issues are addressed to realize a future passenger aircraft propulsion system using the fan concept. Also this paper introduces several propulsion system configurations for future passenger-aircraft propulsion systems with the fan system. Two promising arrangements of the combined system of gas turbine and fuel cell are introduced.