Автор Salo, 03.05.2010 22:38:32
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ЦитатаThe LE-X is a new cryogenic booster engine with high performance, high reliability and low cost, designed for the next-generation Japanese launch vehicle. It will be the first booster engine in the world with an expander cycle. Designed from the heritage of Japan rocket engines, it combines the high pressure component technology of the LE-7A, the first-stage engine of the H-IIA launch vehicle, and the expander bleed cycle system of the LE-5B, the current second-stage engine. One of the characteristics of the LE-X is automatic control of thrust and mixture ratio (LOX/LH2) using electrically actuated valves. The main valves of the current LE-7A are driven by pneumatic actuator. Thrust and mixture ratio at steady-state are adjusted by some orifices in engine pipelines. Therefore, the LE-7A usually tested twice or more before flight to adjust its operating point because each engine has some dispersion from nominal characteristics which is caused by manufacturing variations of each component. When thrust or mixture ratio of a test is not acceptable, the orifices are changed and the engine is tested again. On the other hand, the LE-X is planned to have the ability of adjusting thrust and mixture ratio in the engine operation. The valves of the LE-X are designed to be driven by electric actuator and be able to control propellant flow rate continuously, monitoring signal of some sensors such as chamber pressure, for adjusting its thrust and mixture ratio. This automatic control of thrust and mixture ratio will reduce the engine performance dispersion and number of tests before launch, which leads to less cost and more payload weights. JAXA started the research and development of the automatic control valve system, and plan to verify it in the LE-X prototype engine testing. 3. LE-X engine valve configuration In this section, the LE-X engine system and valve configuration are discussed. The concept of the LE-X engine cycle is shown in Fig. 2. In this system, thrust and mixture ratio are controlled by three electrically actuated valves, namely MFV (Main Fuel Valve), MOV (Main Oxidizer valve), TCV (Thrust Control Valve). TCV controls thrust by controlling the flow rate of turbine drive gas. MOV controls mixture ratio by controlling the pressure of oxidizer at combustion chamber inlet. MFV, which has a step wise propellant flow rate control function, is used for throttling operation to keep turbine inlet temperature within adequate range. To achieve continuous flow rate control, continuous valve positioning system including its control method has to be established. For the continuous valve position control Electro-Mechanical, hydraulic or Electro hydrostatic actuator is needed. EMA (Electro Mechanical Actuator) was selected among those because of its simplicity and easy operation.
ЦитатаНе понял!? Это одноступ? Или у неё будут СТУ?
ЦитатаЦитатаThe main valves of the current LE-7A are driven by pneumatic actuator. Thrust and mixture ratio at steady-state are adjusted by some orifices in engine pipelines. Therefore, the LE-7A usually tested twice or more before flight to adjust its operating point because each engine has some dispersion from nominal characteristics which is caused by manufacturing variations of each component. When thrust or mixture ratio of a test is not acceptable, the orifices are changed and the engine is tested again.
ЦитатаThe main valves of the current LE-7A are driven by pneumatic actuator. Thrust and mixture ratio at steady-state are adjusted by some orifices in engine pipelines. Therefore, the LE-7A usually tested twice or more before flight to adjust its operating point because each engine has some dispersion from nominal characteristics which is caused by manufacturing variations of each component. When thrust or mixture ratio of a test is not acceptable, the orifices are changed and the engine is tested again.
Цитата2. Reference launch vehicle Fig. 1 shows an image of the reference launch vehicle, H-X. JAXA initiated the early-stage feasibility study of the H-X rocket. A version of the H-X candidates for the light payload without solid rocket booster (H-X200) will require the throttling capability of first stage engine to avoid the excessive acceleration in the flight envelope. The requirement of the reference first stage engine is shown in Table 1. 3. LE-X engine cycle One of the features of the LE-X engine is its engine cycle. The engine cycle schematic of the LE-X is shown in Fig. 2. The expander bleed cycle will be applied to the LE-X engine, and the LE-X will be the first booster engine in the world with an expander cycle. In this cycle, hydrogen pumped by the fuel turbopump is partly directed to the main combustion chamber cooling channels and then used to drive the turbines. The turbine drive hydrogen is injected into the main combustion flow at nozzle extension. This cycle has following advantages compared to the staged сombustion cycle adopted in the LE-7A: A) Simple engine configuration B) Reduced maximum system pressure and temperature C) Reduced heat impact to the turbines of turbopump D) Robustness to failure events In the expander bleed cycle engine, a main technical challenge is how to extract turbine power. Turbine drive gas of the expander bleed cycle is regenerative heated hydrogen, therefore, the energy of turbine drive gas depends on combustion chamber heat load, while they are independent in the staged combustion cycle and the gas generator cycle which use combustion energy. In order to increase the turbine energy output, thecombustion chamber of the LE-X will be longer than that of the LE-7A. A longer chamber brings heavier engine weight. A smaller pressure loss though the regenerative coolant channel is preferred from the view of engine performance, which might result in a excessive high temperature at combustion chamber wall. As above, in order to determine properly the system and component specification, it is important to evaluate the whole engine system..
Цитата4.1 Baseline configuration Based on the reference 1st stage specification (Table 1) and the LE-X engine cycle (Fig. 2), LE-X 'baseline' configuration including turbopump inducer, impeller and turbine types is determined by the general engine cycle estimation. The principal specification of the LE-X baseline configuration is shown in Table 2, and the 3D layout model of the LE-X engine is shown in Fig.4. The 100% vacuum thrust of the LE-X engine is set to 1,448kN to maximize the payload transportation capability. The configuration of the FTP and the OTP are shown in Table 3. and Fig. 5. Single stage impeller with 2 stage inducer is applied to the FTP for high pump head with low cost. 4.2 Engine system evaluation functions Optimization of the engine parameters is the goal of this process. The evaluation functions which represent the LE-X system performance, cost and reliability are described as follows. i. Performance Engine performance is estimated by the payload transportation capability to the sun-synchronous orbit (SSO). The capability is function of the engine thrust, weight and specific impulse, defined by a sensitivity analysis of the H-X launch vehicle orbit computation considering the ground radar station, upper-level wind, and so on. ii. Cost Cost is estimated by each component cost model. For example, cost is influenced by the chamber length, impeller diameter, and so on. iii. Reliability In the LE-X engine design, quantitative reliability of the LE-X engine system will be estimated using failure mode effect analysis (FMEA) list which includes every failure mode of the LE-X system and components. Using the FMEA, functions which affect the LE-X engine reliability are extracted. Each function concerning reliability is estimated by distance from design criteria of each component. However, estimation of all of the functions leads to somewhat pointless effort. For example, thickness of the pipeline could be independently designed with little system balance impacts. Therefore, the functions which have the large effect to the engine system balance and cannot be changed independently, are extracted. The reason of the function selection of each component is described as follows. A) Combustion Chamber (MCC) The LE-X combustion chamber consists of large size copper alloy inner liner and steel based superalloy outer shell. Pratt & Whitney Rocketdyne (PWR)'s hot isostatic pressure (HIP) bonding technology will be applied to fabricate the combustion chamber with significantly low cost. To enlarge the energy of the turbine drive gas, the combustion chamber (MCC) is divided into two part, upper chamber, which includes chamber throat and injector interface, and lower chamber. Fig. 5 shows the image of the chamber. The upper chamber inner liner has high temperature part, and the creep and fatigue damage of this part is the most critical for the chamber life. B) Injector (INJ) The injector design affects combustion efficiency and combustion stability, which is one of the technical issues for the LE-X. Especially, combustion instability should be avoided at the baseline design phase. C) Nozzle skirt (NSA) The nozzle skirt is cooled by the turbine drive gas and the gas should be choked at the nozzle skirt exit to stabilize the turbine back pressure. Critical failure mode of NSA is buckling. The temperature of nozzle wall and the pressuere of combustion gas should be controlled by the engine system. D) Main valves (MOV/MFV/TCV/CCV) Eccentric ball valve (Fig. with excellent flow characteristics, shut off capability and light weight, is applied to the LE-X as main valves, which are main oxidizer valve (MOV), main fuel valve (MFV), thrust control valve (TCV), and chamber coolant valve (CCV). Each main valve is driven by electric actuator, and has shaft seals and bearings. Controlling the environment of the shaft seals and bearings is important. E) Fuel turbopump (FTP) Major criteria for the FTP are as follows; - Suction limitation - Rotor dynamics - Bearing life time - Impeller and turbine centrifugal force - Turbine hydrodynamic force - Turbine disk thermal impulse The FTP runs in high rotational speed (more than 40,000rpm), impeller and turbine centrifugal force is critical. In addition, high temperature turbine drive gas flows into the FTP turbine when the engine starts, and the turbine disk might have cracks by the thermal shock. F) Oxidizer turbopump (OTP) Criteria for the OTP are same as th FTP's. The OTP is drived by the relatively low pressure hydrogen gas, therefore, large size turbine disk is necessary. Rotor dynamics and turbine hydrodynamic force is severe compared to the FTP.
Цитатаhttp://www.senkyo.co.jp/ists2008/pdf/2008-a-04.pdfЦитата2. Next flagship Japanese launch vehicle
Цитата2. Next flagship Japanese launch vehicle
ЦитатаТам открытая схема со сбросом отработанного водорода в закритическую часть сопла. И ещё удлинённая КС для увеличения теплоотбора.
ЦитатаА насколько хорошо такая характеристика, как "3 тонны на ССО" соответствует заявленной выше задаче "получить надёжность, пригодную для пилотируемых миссий"? Это какая ПН на орбиту МКС примерно может получиться и что в эту ПН можно реально вложить с точки зрения пилотируемых задач?
ЦитатаА япошки попильщики знатные:) У них уже куча ракет с почти 0 серийностью и одна краше другой в плане сочетания разноплановых технологий которые нивелируют друг-друга до посредственности. Чего только стоит метановая или водородная( уже подзабылось) вытесниловка на 2 ступени.П.С. Единственная полезная информация- расширительный цикл со сбросом с турбины в сопло позволяет, судя по 2 движкам на картинке, иметь 65-70 т тяги на движок. Еще бы знать его УИ. ПМСМ такой 65-70-тонник будет просто идеален для 2 ступени. Нашим конструкторам стоит присмотреться к этой схеме.
ЦитатаПМСМ такой 65-70-тонник будет просто идеален для 2 ступени. Нашим конструкторам стоит присмотреться к этой схеме.
ЦитатаJapan is already evaluating a replacement rocket for the H-2A, but its development has not won final government approval and its first flight is not anticipated until the 2020s, Nakamura told Spaceflight Now.Dubbed the H-X in planning documents, the new launcher would be designed to human-rating standards to support a potential Japenese manned spacecraft."Although we know that there are many obstacles for realization of human transportation in Japan, the discussion of this issue has been more open in recent years," Nakamura said.The Japanese government is already funding studies of upgrading the H-2 Transfer Vehicle, an unmanned resupply freighter for the International Space Station, to return to Earth with cargo. If approved, the re-entry version of the HTV could be designed with a clear emphasis on its future applicability as a manned spacecraft.Engineers have settled on the H-X's basic configuration. It would likely be a two-stage vehicle with liquid-fueled engines and no solid rocket motors.But officials have not determined the specifications and numbers of the engines for the H-X rocket, Nakamura said. A concept drawing of the next-generation H-X rocket. Credit: MHI/JAXA