检索结果-南通市图书馆

LATTICE-BOLTZMAnn MODEL FOR COMPREssIBLE PERFECT GAsEs

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica sinica 2000年第4期16卷 289-300页

作者：孙成海 state Key Laboratory of Tribology Department of Engineering MechanicsTsinghua UniversityBeijing 100084China

We present an adaptive lattice Boltzmann model to simulate super- sonic flows.The particle velocities are determined by the mean velocity and internal energy.The adaptive nature of particle velocities permits the mean flow to have high Mach number.A particle potential energy is introduced so that the model is suitable for the perfect gas with arbitrary specific heat ratio.The navier-stokes equations are derived by the Chapman-Enskog method from the BGK Boltzmann equation. As preliminary tests,two kinds of simulations have been performed on hexagonal lattices.One is the one-dimensional simulation for sinusoidal velocity distributions. The velocity distributions are compared with the analytical solution and the mea- sured viscosity is compared with the theoretical values.The agreements are basically good.However,the discretion error may cause some non-isotropic effects.The other simulation is the 29 degree shock reflection.

关键词： lattice Boltzmann Euler equation n-s equation adaptive velocities perfect gas

sERIEs PERTURBATIOns APPROXIMATE sOLUTIOns TO n-s equations AnD MODIFICATIOn TO AsYMPTOTIC EXPAnsIOn MATCHED METHOD

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2002年第8期23卷 963-972页

作者：李大鸣张红萍高永祥 school of Civil Engineering Tianjin University Tianjin 300072 P R China school of Machinery Engineering Tianjin University Tianjin 300072 P R China

A method that series perturbations approximate solutions to n-s equations with boundary conditions was discussed and adopted. Then the method was proved in which the asymptotic solutions of viscous fluid flow past a sphere were deducted. By the ameliorative asymptotic expansion matched method, the matched functions, are determined easily and the ameliorative curve of drag coefficient is coincident well with measured data in the case that Reynolds number is less than or equal to 40 000.

关键词： asymptotic expansion matched method series perturbation n-s equation viscous fluid flow past a sphere

Aircraft-skin Infrared Radiation Characteristics Modeling and Analysis

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2009年第5期22卷 493-497页

作者： Lu Jianwei Wang Qiang school of Jet Propulsion Beijing University of Aeronautics and Astronautics Beijing 100191 China

One of the most important problems of stealth technology is to evaluate the infrared radiation （IR） level received by IR sensors from fighters to be detected. This article presents a synthetic method for calculating the IR emitted from aircraftskin. By reck- oning the aerodynamic heating and hot engine casing to be the main heat sources of the exposed aircraft-skin, a numerical model of skin temperature distribution is established through computational fluid dynamics （CFD） technique. Based on it, an infrared signature model for solving the complex geometry and structure of a fighter is proposed with the reverse Monte Carlo （RMC） method. Finally, by way of determining the IR intensity from aircraft-skin, the aircraft components that emit the most IR can be identified; and the cooling effects of the main aircraft components on IR intensity are investigated. It is found that reduction by 10 K in the skin temperature of head, vertical stabilizers and wings could lead to decline of more than 8% of the IR intensity on the aircraft-skin in front view while at the broadside of the aircraft, the drops in IR intensity could attain under 8%. The results provide useful reference in designing stealthy aircraft.

关键词： aircraft-skin temperature distribution infrared radiation n-s equation

COMPUTATIOn OF sUPERsOnIC TURBULEnT FLOWFIELD WITH TRAnsVERsE InJECTIOn

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2002年第1期23卷 107-113页

作者：孙得川胡春波蔡体敏 College of Astronautics Northwestern Polytechnical University Xi’an P R China

Three dimensional steady flowfield generated by transverse sonic injection Into a supersonic flow was simulated by solving the Favre-averaged navier-stokes equations using the weighted essentially nonoscillatory (WEnO) schemes and Jones-Launder k-epsilon model. Results indicate that in the upstream of the square injection there exist two main recirculation regions and the primary vortex induces the horseshoe vortex region. In the downstream there is a low pressure region which conduces a pair of helical vortex.

关键词： injection n-s equation kappa-epsilon model weighted EnO scheme

nUMERICAL sTUDY OF DIFFEREnTIAL TORQUE-PRODUCInG JETs In A FLOATED-BALL InERTIAL PLATFORM

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica sinica 1998年第1期14卷 1-9页

作者：章光华朱雅萍 Department of Engineering Mechanics Tsinghua UniversityBeijing 100084China

This paper presents a numerical study of the flow field caused by torque-producing jets in a floated-ball inertial guiding system. The basic flow element studied is the flow in a triangular region of octant sphere surface confined by the two sphere surfaces and the three attitude-driver bands normal to each other. The results show the flow patterns of torque-producing jets and the relations between the effective driving torques and the flow rates under several typical working conditions. The working performances of two kinds of differential torque-producing jets are analyzed and compared. The second kind of differential torque-producing jets, which is first proposed in this paper, has the prominent merit, i.e., the regulation of the three components of driving torque can be realized by non-interference adjustment, so that the three components of angular displacement can be controlled independently.

关键词： floated-ball inertial platform differential torque-producing jets n-s equation Reynolds equation

An Extented Wave Action equation

在线全文

学校读者我要写书评

暂无评论

海洋工程：英文版 2003年第2期17卷 247-254页

作者：左其华 nanjing Hydraulic Research Institute

Based on the navier-stokes equation, an average wave energy equation and a generalized wave action conservation equation are presented in this paper. The turbulence effects on water particle velocity u i and wave s... 详细信息

关键词： n-s equation turbulent motion wave action conservation

numerical Experimental Research of seepage Characteristic for Filled Fracture network

在线全文

学校读者我要写书评

暂无评论

Numerical Experimental Research of Seepage Characteristic fo...