Yoshihiro Naruo

Concept and Preliminary Flight Testing of a Fully Reusable Rocket Vehicle

A fully reusable rocket vehicle is proposed to demonstrate good operability characteristics both on the ground and in e ight. For achieving technical readiness for future space transportation systems, design considerations not only for higher-performance-related issues but also those for good operability are needed. The proposed vehicle is to be used as a sounding rocket and has the capabilities of ballistic e ight, returning to the launch site, and landing vertically, making use of clustered liquid-hydrogen rocket engines. Before the development of this type of reusable rocket was initiated, a small test vehicle with a liquid-hydrogen rocket engine was built and e ight tested. A demonstration of vertical landing and exerciseof turnaround operation forrepeated e ightsare the major objectivesof the test vehicle. Two e ightswere performed in succession, and the e ight-test operation provided many valuable experiences for designing the fully reusable rocket vehicle.

Forced convection heat transfer of subcooled liquid hydrogen in horizontal tubes

Forced flow heat transfers of liquid hydrogen through horizontally-mounted tubes with the diameter of 3.0 mm and 6.0 mm were measured at the pressure of 0.7 MPa for various inlet temperatures and flow velocities. The measured non-boiling heat transfer coefficients agree with those by the Dittus-Boelter correlation. The heat fluxes at the onset of nucleate boiling and the departure from nucleate boiling (DNB) heat fluxes, where the heat transfer continuously changes to film boiling regime, are higher for higher flow velocity, larger subcooling and larger tube diameter. The DNB heat fluxes for the horizontally-mounted tube are slightly lower than those for the vertically-mounted tube, although the effect of the tube attitude direction disappears for a small tube diameter. The measured DNB heat fluxes agree with the correlation for vertically-mounted tubes.

PRELIMINARY STUDY ON HEAT TRANSFER CHARACTERISTICS OF LIQUID HYDROGEN FOR COOLANT OF HTC SUPERCONDUCTORS

Liquid hydrogen is expected as a coolant for a HTS superconducting magnet because of its excellent cooling properties. However, there has been a lack of an extensive heat transfer data of liquid hydrogen in forced flow condition for superconductor cooling.As a first step of the study, the experimental setup, which can be used for investigating heat transfer characteristics of liquid hydrogen in a pool and also in forced flow for wide range of sub‐coolings, flow velocities and pressures up to supercritical condition, have been designed and fabricated. The mass flow rates during the forced flow tests were measured by the weight change of the main cryostat. All the control valves, the heating control and measuring system were remote‐operated through optical fiber connected computer controls. It was confirmed that the control and measuring systems were operated well as designed.A basic test of heat transfer in liquid hydrogen was carried out by quasi‐steadily increasing heat inputs to horizontal flat plate wi...

Development of a thermal-hydraulics experimental system for high Tc superconductors cooled by liquid hydrogen

A thermal-hydraulics experimental system of liquid hydrogen was developed in order to investigate the forced flow heat transfer characteristics in the various cooling channels for wide ranges of subcoolings, flow velocities, and pressures up to supercritical. A main tank is connected to a sub tank through a hydrogen transfer line with a control valve. A channel heater is located at one end of the transfer line in the main tank. Forced flow through the channel is produced by adjusting the pressure difference between the tanks and the valve opening. The mass flow rate is measured from the weight change of the main tank. For the explosion protection, electrical equipments are covered with a nitrogen gas blanket layer and a remote control system was established. The first cryogenic performance tests confirmed that the experimental system had satisfied with the required performances. The forced convection heat transfer characteristics was successfully measured at the pressure of 0.7 MPa for various flow velocities.

GaN HEMT based rectifier for spacecraft health monitoring system using microwave wireless power transfer

High power operable and miniaturized rectifier is one of the most important issues for spacecraft health monitoring system. This is because the flexibility of location, number, and power consumption regarding sensor tag is indispensable for reliable health monitoring. Previous single rectifiers focusing on schottky diode are unsuitable since operating at high power and considering integrated MMIC sensor tags are quite difficult. This research proposes GaN HEMT based rectifier for these issues due to its excellent properties such as structurally-preferable for MMIC, and suitable for high power operation. Design and evaluation of GaN HEMT based rectifier and an experiment using the rectifier and a thermal sensor with microwave wireless power transfer has been conducted. The proposed rectifier can be operated with 47 dBm input RF signal.

Heat Exchange and Pressure Drop Enhanced by Sloshing

For the prediction of heat transfer coupled with sloshing phenomena in the propellant tanks of reusable launch vehicle, the pressure drop induced by heat transfer and the dynamic motion of liquid in sub-scale vessels were experimentally observed and numerically investigated. The correlation between the pressure drop and liquid motion was confirmed in the experiment. The mechanisms enhancing heat transfer were discussed based on the computation. It was suggested that splash and wavy surface induced by violent motion of liquid cause the pressure drop in the closed vessel. In addition, as the preliminary investigation, non-isothermal sloshing of liquid nitrogen and liquid hydrogen were successfully visualized and pressure drop depending on the gaseous species was discussed.

Test results of the air turbo ramjet for a future space plane

Abstract The Institute of Space and Astronautical Science (ISAS) has been engaged in the development study on the Air Turbo Ramjet (ATR) engine since 1986 in cooperation with the Ishikawajima Harima Heavy Industries Co. Ltd (IHI). The ATR is one of the most preferable candidates for the propulsion system of a future space plane. Our ATR engine is a combined cycle air breathing propulsion system which consists of the turbojet and the fan boosted ramjet using the liquid hydrogen as a fuel. This engine system was named “ATREX” after employing the expander cycle. The ATREX is energized by thermal energy extracted regeneratively in both the pre-cooler installed in the air intake and the heat exchanger in combustion chamber. The ATREX works in the flight condition from sea level static up to Mach 6 at 35 km altitude. The ATREX employs the tip turbine configuration for compactness of turbo machinery. We are assessing the feasibility of the ATREX system by the sea level static tests using the 1 4 - scale model (ATREX-500) with a fan inlet diameter of 300 mm and overall length of 2120 mm. In 1990, the ATREX-500 engine was tested in a sea level static condition to verify the performance characteristics of the turbo machinery and the combustor. In September of 1991, the heat exchanger was installed in the combustion chamber and tested independently from the turbo system. In November of 1991, the heat exchanger was coupled with the turbo system and tested to verify the overall system of the ATREX. In this paper are presented the test results of the ATREX-500 engine tested in the sea level static condition.

Preliminary experiment on LOX/LH2 high pressure expander cycle engine☆

Abstract The expander cycle has high performance and high reliability. This has been verified by the Pratt & Whitney RL 10 engine that is used to power the Centaur upper stage. Some limitations, however, exist in this cycle on increasing both chamber pressure and thrust because it uses only the heat energy absorbed by the fuel as it cools the thrust chamber and nozzle extension to power the fuel and oxidizer turbopumps. We have proposed the advanced concept chamber with an internal heat exchanger at the 35th IAF congress , Lausanne in order to pick up the large amount heat from combusion energy. This paper describes the brief features of high pressure expander cycle engine using an internal heat exchanger and the results of preliminary tests on the thrust chamber with internal heat exchanger. The average heat flux in heat exchager became about 70% of the value calculated by Bartzs correlation. The combusion performance was not affected significantly by installing a heat exchanger within a combustion chamber.

Forced convection heat transfer of saturated liquid hydrogen in vertically-mounted heated pipes

Heat transfer from the inner side of vertically-mounted heated pipes to forced flow of saturated liquid hydrogen was measured with a quasi-steady increase of a heat generation rate for wide ranges of flow rate and saturated pressure. The tube heaters have lengths L of 100 mm and 167 mm with the diameter D of 4 mm and lengths of 150 mm and 250 mm with the diameter of 6 mm. The heat fluxes at departure from nucleate boiling (DNB) were higher for higher flow velocity, lower pressures and shorter L/D. The effect of L/D on the DNB heat flux was clarified. It is confirmed that our DNB correlation can describe the experimental data.

Transient heat transfer from a horizontal flat plate in a pool of liquid hydrogen

Transient heat transfer caused by exponentially increasing heat input (Q=Q0exp(t/τ)) to a flat plate in a pool of liquid hydrogen was measured under saturated and subcooled conditions at pressures from 104 to 700 kPa. The exponential period τ was varied from 8 ms to 8 s and the liquid subcoolings from 0 to 8 K. The flat plate heater used was 5 mm in width, 60 mm in length and 0.5 mm in thickness. Transient heat transfer before the inception of boiling for the exponential period shorter than 100 ms was expressed well by the transient conduction heat transfer with no movement of liquid. Incipient boiling heat flux and temperature were higher for shorter period. Transient critical heat flux was higher for shorter exponential period and higher subcooling. No direct transition from non-boiling to nucleate boiling such as first found by some of the authors for transient heat transfer in a pool of liquid nitrogen was observed for liquid hydrogen. An equation for transient critical heat flux was given.