Combustion possibility assessment for separating launch-vehicle components during atmospheric phase of descent trajectory

The present work computationally investigated the combined effects of thermal non-equilibrium and chemical reactions on hypersonic air flows around an orbital reentry vehicle during its reentry. The chemically reacting gas flow around the orbital vehicle was simulated for actual reentry trajectories, with a computational solver based on the Navier–Stokes–Fourier equations. Hypersonic flows for a wide range of flying altitudes from 40 to 80 km were examined. We first analyzed important properties such as Mach number, trans-rotational temperature, vibrational temperature, chemical species composition, and surface properties such as the maximum heat flux for various altitudes. We then investigated the distribution of heat flux on the surface of the orbital reentry vehicle and the coupled effects of thermal non-equilibrium and chemical reactions on the hypersonic air flows. The computed heat flux results were compared with actual flight test data obtained during reentry of the orbital vehicle. The computed results were found to be in excellent agreement with the flight test data until an altitude of 60 km. Finally, we propose an explanation why heat flux was over-predicted around 70 km altitude but returned to better agreement at the higher altitude of 80 km. The phenomenon is based on two competing effects: the shortcoming of the first-order law of heat flux in the NSF equations and the inaccurate description of the effects of thermal non-equilibrium on chemical reactions in Park’s two temperature model.

Combined Effects of Thermal Non-equilibrium and Chemical Reactions on Hypersonic Air Flows Around An Orbital Reentry Vehicle

The basic quantitative tool for the study of hypersonic rarefied flows is the direct simulation Monte Carlo method (DSMC). The DSMC method requires a large amount of computer memory and performance and is unreasonably expensive at the first stage of spacecraft design and trajectory analysis. A possible solution to this problem is approximate engineering methods. However, the Monte Carlo method remains the most reliable approach to compare to the engineering methods that provide good results for the global aerodynamic coefficients of various geometry designs. This paper presents the calculation results of aerodynamic characteristics for spacecraft vehicles in the free molecular, the transitional and the continuum regimes using the local engineering method. Results and methods would be useful to calculate aerodynamics for new-generation hypersonic vehicle designs.

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Aerodynamic Investigation for Prospective Aerospace Vehicle in the Transitional Regime

This paper deals with the computational analysis of aerodynamics of space vehicle entering the Earth's atmosphere (from the free-molecular regime to the continuum flow regime) in rarefied gas flow. The use of approximate engineering methods is the most favorable approach to solve problems of spacecraft aerodynamics at the stage of conceptual design. In this paper present the calculation results of aerodynamic characteristics of new generation space vehicle in free molecular, the transitional and continuum regimes by using engineering method. This method may useful to calculate aerodynamic characteristics of new generation space vehicle designs.

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Aerodynamic Characteristics Calculation for New Generation Space Vehicle in Rarefied Gas Flow

A scaled model of the X38-like configuration was simulated under hypersonic conditions for the direct simulation Monte Carlo method and the unified gas kinetic scheme. The inflow conditions considered several flow regimes, from the near-continuum through the slip-transitional to the free molecular regime. Flow fields and surface properties were compared in detail between these two methods. Not only the density and temperature contours distribution but also the surface pressure, heat flux, friction distribution, both kinetic methods give fairly consistent results. Aerodynamics of the model were also achieved and compared. The results provided by both methods agreed with each other very well. The effects of the Knudsen number and angle of attack were assessed. It is meaningful to carry out comparative studies and accelerate both methods to further progress.

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Kinetic comparative study on aerodynamic characteristics of hypersonic reentry vehicle from near-continuous flow to free molecular flow

Aerodynamic characteristics of an aircraft with a complex shape taking into account the potential of molecular flowinteraction with a surface

The purpose of this work is to describe the suitable methods for aerodynamic characteristics calculation of hypersonic vehicles in free molecular flow and the transitional regimes. Moving of the hypersonic vehicles at high altitude, it is necessary to know the behavior of its aerodynamic characteristics for all flow regimes. Nowadays, various engineering approaches have been developed for modelling of aerodynamics of aircraft vehicle designs at initial state. The engineering method that described in this paper provides good results for the aerodynamic characteristics of various geometry designs of hypersonic vehicles in the transitional regime. In this paper present the calculation results of aerodynamic characteristics of various hypersonic vehicles in all range of regimes by using engineering method.

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Computer Modelling of Aerothermodynamic Characteristics for Hypersonic Vehicles

The purpose of this work is to analysis the history and future development of hypersonic vehicles all over the world and to determine the aerodynamic and aerothermodynamic characteristics of prospective hypersonic vehicles by using engineering methods at all range of flow regimes (free-molecular, transitional and continuum regimes). In this paper present the calculation results of aerodynamic and aerothermodynamic characteristics of prospective hypersonic vehicle.

Modern Trends in the Development of Reusable Aerospace System

The major function of parallel computing system is how to coordinate communication between the various processors. Some parallel computing techniques require specialized programming to permit the processors to work together in parallel. It can be seen that on Monte Carlo simulations, algorithms proceed by averaging large numbers of computed values. It is sometimes straightforward to have different processors compute different values, and then use an appropriate average of these values to produce a final result. In this paper give an introduction to the generalized Monte Carlo method and its related algorithms. This paper aims to describe Monte Carlo methods with parallel computing techniques and to present some Monte Carlo algorithms to solve some problems in gas dynamics.

http://www.openscienceonline.com/author/download?paperId=1292&stateId=8000&fileType=3

Zay Yar Myo Myint

Papers

Aerodynamic characteristics of an aircraft with a complex shape taking into account the potential of molecular flowinteraction with a surface

Aerodynamic Characteristics Calculation for New Generation Space Vehicle in Rarefied Gas Flow

Computer Modelling of Aerothermodynamic Characteristics for Hypersonic Vehicles

Modern Trends in the Development of Reusable Aerospace System

Monte Carlo Method and Its Parallel Computing Technique in Molecular Gas Dynamics