Chu M.,Beihang University |
Xu X.,Beihang University |
Xu X.-Y.,Beijing Aerospace Propulsion Institute
Tuijin Jishu/Journal of Propulsion Technology | Year: 2013
Numerical simulation on start-up process in thrust chamber of hydrogen-oxygen rocket engine was performed by computational fluid dynamics method. Dual-time-step method and steady laminar flamelet model were utilized to simulate the unsteady process and combustion process, respectively. The database of flamelet model was set up by 8 steps with 6 specices chemical reaction model. The pressure curve and the detailed parameters of flowfield were achieved from the simulation, which was performed according to the time sequence of start-up process. It turns out that, the steady laminar flamelet model is available to the start-up process and the pressure curve shows good consistency with the test curve.
Nan Z.,Beijing Aerospace Propulsion Institute
Proceedings of the International Astronautical Congress, IAC | Year: 2013
Because of its high specific impulse and environmental-friendly feature, LOX/LH2 engine has a special standing in aerospace propulsion domain, and has gained great attention worldwide. Since 1960's, China has been working on the development of LOX/LH2 engine. Developed from nothing, China has broken through a great number of key technologies and accumulated abundant experiences. In 1984, we successfully launched China's first geosynchronous communication satellite using 4 tonne thrust LOX/LH2 engine as the upper stage propulsion of CZ-3 Launch vehicle. Since then we developed 8 tonne thrust YF-75 engine with higher performance as the upper stage engine of CZ-3A launch vehicle. Preparing for the new generation launch vehicle CZ-5, we are developing 9 tonne thrust expander cycle upper stage engine YF-75D and 50 tonne thrust main engine YF-77. Till now we have made some major breakthrough in terms of their design, material, manufacture, and test. In the future, the developing of LOX/LH2 engine with higher thrust is inevitable. Thus, we are now having deep studies of key technologies concerning its system, thrust chamber, turbo pump, valves, etc. Copyright © 2013 by the International Astronautical Federation. All rights reserved.
Zhu Y.,Tsinghua University |
Jiang P.,Tsinghua University |
Sun J.,Beijing Aerospace Propulsion Institute |
Xiong Y.,Tsinghua University
Journal of Thermophysics and Heat Transfer | Year: 2013
Transpiration cooling coupled with combustion was investigated in an H 2/O2 liquid rocket thrust chamber with a transpiration-cooled injector plate.Anumericalmodelwasdevelopedusingthe real gas equationof state.TheH2 andO2 combustion process was modeled by the eddy dissipation concept model, which includes the detailed chemical reaction mechanismsin turbulent flows.The permeability and the inertia coefficient of themetalmesh, porousmedia used for the injector plate were obtained experimentally. The simulation results for the porous plate temperatures and H2 fluxes comparewellwithhot firing experiments, giving reliable predictions of the combustion, flow, andheat transfer processes in the liquid rocket thrust chamber.Themodelwas also used to investigate the effects of the inlet conditions and the plate material on the transpiration cooling. The results showthat locations near the chamberwall and the ignition hole on the plate surface have higher temperatures than other locations. The relatively small thermal conductivity of the porous media is also shown to decrease the plate surface temperature, but increase the thermal stress in the plate. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
Dou W.,Beijing Aerospace Propulsion Institute
Tuijin Jishu/Journal of Propulsion Technology | Year: 2013
The affecting factors of the dynamic stability were studied for the turbine pump rotor system of low temperature liquid rocket engine. The dynamic model of nonlinear rotor system was established by using the Finite Element Method. The effects of installation eccentricity was studied on the stability of the rotor system. The change rule of instability speed was obtained along the installation eccentricity. The effects of the equivalent seal clearance, bearing supporting total stiffness and bearing axial position were investigated on the stability of the rotor-seal system under condition of installation eccentricity. The effects of equivalent seal clearance, bearing supporting total stiffness and bearing axial position were analyzed on instability speed. At last, the tests are performed to validate the theortical results. This study supplies a reference for optimum design and fault diagnosis and safe operation of the turbine pump rotor of liquid rocket engine.
Li X.X.,Beijing Aerospace Propulsion Institute
IOP Conference Series: Earth and Environmental Science | Year: 2012
To improve performance and design of the cryogenic pump, analyze and solve the pump fault, and ensure the reliability of design and operating, it is highly necessary to understand the cryogenic pump temperature profile. Regarding horizontal single cryogenic centrifugal pump as the studied object, the flow field and structural heat transfer is calculated and analyzed. Based on reasonable boundary condition, three dimensional steady state of the pump mesh model is calculated by finite-element method with the software of Fluent, the fluid pressure field and the whole structural temperature profile is obtained. The structural temperature profile by finite-element heat transfer calculation indicates that: in the operating range of the cryogenic pump, the pumping cryogenic liquid is unable to vaporize at the room temperature, and the low temperature area is unable to interfere with the gear case in normal operation. © Published under licence by IOP Publishing Ltd.
Liu J.,China University of Petroleum - Beijing |
Li S.C.,Beijing Aerospace Propulsion Institute |
Luo X.,China University of Petroleum - Beijing
Computational and Mathematical Methods in Medicine | Year: 2013
Support vector machine is an effective classification and regression method that uses machine learning theory to maximize the predictive accuracy while avoiding overfitting of data. L2 regularization has been commonly used. If the training dataset contains many noise variables, L1 regularization SVM will provide a better performance. However, both L1 and L2 are not the optimal regularization method when handing a large number of redundant values and only a small amount of data points is useful for machine learning. We have therefore proposed an adaptive learning algorithm using the iterative reweighted p-norm regularization support vector machine for 0 < p ≤ 2. A simulated data set was created to evaluate the algorithm. It was shown that a p value of 0.8 was able to produce better feature selection rate with high accuracy. Four cancer data sets from public data banks were used also for the evaluation. All four evaluations show that the new adaptive algorithm was able to achieve the optimal prediction error using a p value less than L1 norm. Moreover, we observe that the proposed Lp penalty is more robust to noise variables than the L1 and L2 penalties. © 2013 Jianwei Liu et al.
Liu Y.-Q.,Tsinghua University |
Jiang P.-X.,Tsinghua University |
Jin S.-S.,Tsinghua University |
Sun J.-G.,Beijing Aerospace Propulsion Institute
International Journal of Heat and Mass Transfer | Year: 2010
The transpiration cooling mechanisms used for thermal protection of a nose cone was investigated experimentally and numerically for various cooling gases. The effects of injection rates, model geometry, inlet temperature and Reynolds number of the main stream were studied for air, nitrogen, argon, carbon dioxide and helium. The experiments used a hot gas wind tunnel with T∞ = 375 K and 425 K and Re∞ = 4630-10,000. The experimental results indicated that even a small amount of coolant injection drastically reduced the heat transfer from the hot gases with the cooling effectiveness increasing with increasing injection rate, although the increases became smaller as the gas injection rate was further increased. The temperature and cooling effectiveness distribution along the transpiration surface of the nose cone model exhibited similar tendencies for all the coolants employed in present experimental research. The temperature decreased from the stagnation point towards the downstream region, then increased because of the non-uniform mass flow distribution of the coolant and thermal conduction from the metal backplane, whereas the cooling effectiveness variation was the reverse. The local cooling effectivenesses and thermal capacities were found to depend on the coolant thermophysical properties. Two-dimensional numerical simulations using the RNG κ- turbulence model for the main stream flow and the Darcy-Brinkman-Forchheimer momentum equations and thermal equilibrium model for the porous zone compared well with the general features in the experiments. © 2010 Elsevier Ltd. All rights reserved.
Dou W.,Beijing Aerospace Propulsion Institute
Yuhang Xuebao/Journal of Astronautics | Year: 2013
The dynamics stability research is carried out for the turbine pump rotor-seal system of a cryogenic liquid rocket engine. The rotor-seal system dynamics model is established. The effect of installation eccentricity on the stability of the rotor-seal system is researched. The change rule of instability speed with installation eccentricity is given. The effect of the equivalent seal clearance is researched on the stability of the rotor-seal system. The effect of equivalent seal clearance on instability speed is analyzed. At last, the tests are finished to validate the theoretical result in this paper. This study provides a theoretical basis for optimum design, fault diagnosis and safe operation of liquid rocket engine turbine pump rotor system.
Dou W.,Beijing Aerospace Propulsion Institute |
Zhang N.,Beijing Aerospace Propulsion Institute |
Liu Z.-S.,Harbin Institute of Technology
Zhendong Gongcheng Xuebao/Journal of Vibration Engineering | Year: 2011
The model of coupled bending and torsional nonlinear vibrations in which the gearing mesh and torsion action are considered is established for high-speed geared rotor-bearing system. The dynamics differential equation of coupled bending and torsional nonlinear vibrations is deduced for imbalance rotors. The characteristic graph of coupled bending and torsional vibrations is gained through the numerical simulation for geared rotor-bearing system under working speed. The coupled bending and torsional vibrations characteristic is educed under gearing mesh and torsion action. The effect law of eccentric distance parameter and gear stiffness parameter etc. is studied on the system vibration response. This study supplies a theory for optimum design and fault diagnosis and safe operation of geared rotor-bearing coupled system.
Beijing Aerospace Propulsion Institute | Date: 2010-11-02
A disc valve with a diversion hole for a solid granule medium aims to solve the problem of material accumulation in a valve cavity and includes a valve body with a valve passage, the valve cavity communicated with the valve passage is formed in the valve body, a valve disc for closing and opening the passage is arranged in the valve cavity, the valve disc is fixedly connected with a valve rod through a valve rod connecting hole of an eyeglasses plate, and the eyeglasses plate is also provided with the diversion hole and a hole for placing the valve disc. The outer wall diameter of the diversion hole is greater than the diameter of the valve passage, and the height of the diversion hole is the same as the length of the valve passage passing through the valve cavity.