Papers by Keyword: Aerodynamic Heating

Abstract: The conjugate problem of aerodynamic heating of a blunted cone moving in the atmosphere at angle of attack at supersonic speed is considered. Three modifications of a thermal protection material based on coal-plastic with different proportions of a phenol-formalhyde binder and a carbon cloth are investigated. The effect of the material composition on the surface temperature and the mass loss characteristics is analyzed.

Abstract: Aerodynamic heating will be caused when a hypersonic vehicle is in flight, so it should be taken into account when a structural dynamic analysis is carried out. A method for structural dynamic analysis under thermal environment is presented in this paper. Firstly, Computational Fluid Dynamic (CFD) method which is based on solving the three-dimensional compressible Navier-Stokes (N-S) equations is employed to perform aerodynamic heating analysis. Secondly, Finite Element Method (FEM) is used to assess structural heat conduction and get temperature field. Lastly, based on the quasi-linear structural model, a structural dynamic analysis is analyzed under thermal environment. A hypersonic composite wing is investigated as a numerical example. Compared with the case without considering aerodynamic heating, major modes and frequencies of the wing change a lot because of the decrease of the elastic modulus and the alteration of structural stiffness distribution. The results indicate that the aerodynamic heating has a high influence on the vibration characteristics. Therefore, aerodynamic heating should be considered in hypersonic structural dynamic analysis.

Abstract: In the present work, the surface temperature history of a metal shell of the blunt nose of supersonic launch vehicle which is covered by a thermal protection coating is numerically predicted and compared with experimental data. The full Navier-Stokes equations are used to estimate the aerodynamic heat flux during flight, coupled with the governing equations for the thermal protection system to study the erosion rate and temperature variations. The results show the importance of the properties of the coating on accuracy of the numerical predictions.

Abstract: The letter relying on the status of existing thermal protection system and existing flight parameters, appropriate metal thermal protection system being able to reproduced are designed; according to the distribution of heat-flow density we make certain the structure and thickness of the heat shield, structure of cooling bed and pressure of cooling air, velocity of flow and so on. The distributions of temperature of points on the nose and the inside of skin are calculated.

Abstract: Relying on the status of existing thermal protection system and existing flight parameters, appropriate metal thermal protection system being able to reproduced are designed. Then, based on the highest temperature thermal protection materials can bear, flying height of aerospace plane and Mach number, the numerical method was utilized to reveal the heat-flow density of stagnation point on the sharp- nose and the distribution of heat-flow density.

Abstract: The severe aerodynamic heating on the surface of modern hypersonic flight vehicle, that can bring high temperature and large temperature gradients in the structure of the vehicle, will be a challenge for the vehicles design and multidisciplinary optimization. The transient thermal environment consists of high temperature and large temperature gradients will generate two important problems related to vehicle structure, namely: 1) the material property, such as elastic modulus, will be degraded at elevated temperature, and 2) the non-uniform thermal stress cased by large temperature gradients will change the stiffness distribution of wing structure, which can make the modal frequencies and shapes of structure changed remarkably. Firstly, the theory and methodology of structure modal analysis in transient thermal environment is outlined. Subsequently, the transient temperature field of structure considering aerodynamic heating is obtained by employing computational technology of aerodynamic heating/structure heat transfer coupling program. Finally, the modal frequencies and shapes of vehicle structure under transient temperature field is calculated based on finite element method (FEM). Based on the analysis and investigation of the simulation results, the influence of the transient thermal environment on structure modal frequency and shape is determined. Furthermore, the investigation of wing structure modal analysis considering aerodynamic heating is an important basis of aerothermoelastic simulation.

Abstract: The aerodynamic heating and infrared radiation characteristics of BrahMos supersonic cruise missile were investigated. The aerodynamic heating was simulated using finite volume method, and the infrared radiation characteristics were simulated by reverse Monte Carlo method. Infrared radiation characteristics of missile surface were analyzed in different surface emissivity and flight altitudes, and the effects of environmental radiation and atmospheric attenuation were considered. The results show 8~14μm and 3~5μm environment radiation were approximately 10% and 2.4% of total radiation respectively, when the surface emissivity is 0.3. The proportion of environmental radiation reduces nearly half when the surface emissivity increases by 0.2.

Abstract: The long-stored missile as a result of environment temperature stress functions and so on, it will cause the missile material aging. For high-speed flight's missile, thermal coefficient of expansion between the different structural and element will be different simultaneously, when the aerodynamic heating will produce, the grain and the thermal insulation layer will also be appeared the crack phenomenon in the influence of expand with heat and contract with cold rules. For the example of some infra-red missile, aero-thermodynamic effect of the missile is carried on the forecast using the ANSYS software simulation, it has the important meaning to analyze the storage performance and failure mechanism of flying missile and so on.

Abstract: The cooling effect of a film cooling thermal protection system is investigated, and the flow field, aerodynamic force and surface temperature distribution are obtained. The numerical method is validated by experiment with no film cooling. The physical mechanism of the reduction of temperature is analyzed. The jet interacts with the free stream to form a thermal insulating layer on the wall, which enables the free stream to flow outside the wall rather than interact with the surface to produce aerodynamic heating. In addition, the film cooling flow form a cool recirculation region, which reduces the temperature on the surface. Analysis of the numerical simulation results shows that this kind of thermal protection system has an excellent cooling effect on the surface of the nose-tip. With the outlet speed increasing, the cooling efficiency is improved and the aerodynamic resistance is changeless. When outlet speed and total pressure are invariable, the cooling effect of air and nitrogen is the same, but the cooling effect of helium is better.

Abstract: The characteristics of the transient heating control process of aerodynamic simulation experiments are complicated, transient, highly nonlinear, and strongly coupled, which make it difficult or impossible to develop a mathematical model. By using the fuzzy control method, many good qualities (such as robustness, high adaptability to changing parameters, and a short transition process time) can be obtained. Based on the fuzzy control method, a transient aerodynamic heating simulation control system for missiles was established. It was demonstrated that quick dynamic control of the aerodynamic simulation heating process according to the transient and continual change in heat flow on the surface of high-speed aircrafts can be completed by using this control system.