Download or read book Development and Application of a Nonequilibrium Magnetohydrodynamics Code to Hypersonic Flow Power Generation written by Heath Lorzel and published by . This book was released on 2010 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Magnetohydrodynamics Power Generation and Theory written by and published by . This book was released on 1975 with total page 884 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Direct Numerical Solution of the Three dimensional Generalized Boltzmann Equation for Hypersonic Non equilibrium Flows written by Christopher Daniel Wilson and published by . This book was released on 2010 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development and applications of a computer code for solving the three-dimensional generalized Boltzmann equation (GBE) using a direct numerical method are presented. The Boltzmann solver of Professor Felix G. Tcheremissine of the Russian Academy of Science serves as the foundation for the development effort. This jet code includes only the translational and rotational energy states of a diatomic gas and has been applied to simulate the flow field of a jet issuing into a vacuum. In this dissertation, this code is employed to accomplish three distinct developmental steps. First, the code is extended for calculating hypersonic shock waves in an inert mixture of gases. For this purpose, the GBE is formulated in an impulse space (instead of the conventional velocity space). The computational methodology is then applied to a binary mixture of gases, which requires the simultaneous solution of four GBE's. Simulations are performed using a gas mixture including both diatomic and monatomic gases in proportions similar to that in air. The solutions are validated against existing hypersonic shock wave experimental data for a single specie gas (nitrogen) in rotational-translational non-equilibrium and available computational data for a binary mixture of monatomic gases. Simulations are then performed for an inert binary mixture of monatomic and diatomic gases in translational non-equilibrium for various concentrations. The effect of mass ratio and molecular diameter ratio of the gases on the structure of the shock is also investigated. Second, boundary conditions necessary for accurately simulating the flows around immersed bodies are developed and evaluated. This research on boundary conditions constitutes a significant advancement beyond the adsorptive boundary condition used in the original Boltzmann solver of Tcheremissine. Five types of boundary conditions at the solid boundary are investigated: (a) the standard adsorptive boundary condition, (b) the specular reflection boundary condition, (c) the diffuse reflection boundary condition, (d) the Maxwellian boundary condition, and (e) the adsorptive Maxwellian boundary condition with different values for the accommodation coefficient. These boundary conditions are tested for hypersonic flow past a flat plate to evaluate their accuracy. Third, the original Boltzmann code, hard-coded for solving the flow field of a jet issuing into a vacuum, is modified to enable simulations of rarefied flows around immersed bodies. The computations are performed for three benchmark geometries, extensively used in the literature for Navier-Stokes simulations, at various hypersonic inflow conditions for flow of a diatomic gas (N2) in rotational-translational non-equilibrium. The three geometries used in the simulations are an axisymmetric blunt body, an axisymmetric bicone, and an axisymmetric hollow-flared-cylinder. Initially, a relatively coarse Cartesian grid was employed in the three-dimensional simulations because of the limitations of physical memory on the available computers. As a result, a shared memory parallel computing platform was developed and built for the sole purpose of being able to perform the fine grid solutions. Consequently, refined grid solutions were generated on the parallel computing platform. For this purpose, the code was parallelized and the parallelization issues for a Boltzmann type solver were addressed. A comparison between the coarse and refined grid solutions is presented to show the influence of grid density on solution accuracy. In light of these results, the issues of accuracy and efficiency of the three-dimensional Boltzmann solver are addressed.
Download or read book 35th AIAA Plasmadynamics and Lasers Conference 04 2435 04 2743 written by and published by . This book was released on 2004 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Quantifying Non Equilibrium in Hypersonic Flows Using Entropy Generation written by and published by . This book was released on 2007 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: The constitutive relations traditionally used for finding shear stress and heat flux in a fluid become invalid in non-equilibrium flow. Their derivation from kinetic theory only demonstrates they are valid only for small deviations from equilibrium. Because it is fundamentally linked to non-equilibrium, entropy generation is used to investigate the limits of the continuum constitutive relations. However, the continuum equations are inherently limited to near equilibrium conditions due to the constitutive relations; thus kinetic theory must be used as a basis for comparison. Direct Simulation Monte Carlo (DSMC), a particle method alternative to continuum methods, is based on kinetic theory and is used to develop a flow solution free from equilibrium assumptions. Solutions were obtained for hypersonic flow over two axisymmetric geometries using both a continuum solver and DSMC. Formulations for entropy generation are presented for each method, and the two solutions are compared. The continuum solver fails to capture regions of non-equilibrium as evidenced by thicker shocks in the DSMC solution. To extend the useful range of the continuum constitutive relations, the Lennard-Jones model is offered as an alternative to Sutherland?s Law for calculating viscosity and thermal conductivity. The two are compared, and parameters offering a good fit for these flows are suggested for the Lennard-Jones model.
Download or read book Computational Fluid Dynamics for the 21st Century written by Mohamed Hafez and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains new trends of computational fluid dynamics for the 21st century and consists of papers especially useful to the younger generation of scientists and engineers in this field. Topics include cartesian, gridless and higher-order schemes, and flow-visualization techniques.
Download or read book Quantifying Non equilibrium in Hypersonic Flows Using Entropy Generation written by Ryan W. Carr and published by . This book was released on 2007 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book AIAA Journal written by American Institute of Aeronautics and Astronautics and published by . This book was released on 2005 with total page 868 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Engineering Aspects of Magnetohydrodynamics written by and published by . This book was released on 1997 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1973 with total page 1256 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Finite Element Segregated Method for Thermo chemical Equilibrium and Nonequilibrium Hypersonic Flows Using Adapted Grids written by and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analytical and Computational Investigations of a Magnetohydrodynamic MHD Energy bypass System for Supersonic Gas Turbine Engines to Enable Hypersonic Flight written by Theresa Louise Benyo and published by . This book was released on 2013 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: Historically, the National Aeronautics and Space Administration (NASA) has used rocket-powered vehicles as launch vehicles for access to space. A familiar example is the Space Shuttle launch system. These vehicles carry both fuel and oxidizer onboard. If an external oxidizer (such as the Earth's atmosphere) is utilized, the need to carry an onboard oxidizer is eliminated, and future launch vehicles could carry a larger payload into orbit at a fraction of the total fuel expenditure. For this reason, NASA is currently researching the use of air-breathing engines to power the first stage of two-stage-to-orbit hypersonic launch systems. Removing the need to carry an onboard oxidizer leads also to reductions in total vehicle weight at liftoff. This in turn reduces the total mass of propellant required, and thus decreases the cost of carrying a specific payload into orbit or beyond. However, achieving hypersonic flight with air-breathing jet engines has several technical challenges. These challenges, such as the mode transition from supersonic to hypersonic engine operation, are under study in NASA's Fundamental Aeronautics Program. One propulsion concept that is being explored is a magnetohydrodynamic (MHD) energy- bypass generator coupled with an off-the-shelf turbojet/turbofan. It is anticipated that this engine will be capable of operation from takeoff to Mach 7 in a single flowpath without mode transition. The MHD energy bypass consists of an MHD generator placed directly upstream of the engine, and converts a portion of the enthalpy of the inlet flow through the engine into electrical current. This reduction in flow enthalpy corresponds to a reduced Mach number at the turbojet inlet so that the engine stays within its design constraints. Furthermore, the generated electrical current may then be used to power aircraft systems or an MHD accelerator positioned downstream of the turbojet. The MHD accelerator operates in reverse of the MHD generator, re-accelerating the exhaust flow from the engine by converting electrical current back into flow enthalpy to increase thrust. Though there has been considerable research into the use of MHD generators to produce electricity for industrial power plants, interest in the technology for flight-weight aerospace applications has developed only recently. In this research, electromagnetic fields coupled with weakly ionzed gases to slow hypersonic airflow were investigated within the confines of an MHD energy-bypass system with the goal of showing that it is possible for an air-breathing engine to transition from takeoff to Mach 7 without carrying a rocket propulsion system along with it. The MHD energy-bypass system was modeled for use on a supersonic turbojet engine. The model included all components envisioned for an MHD energy-bypass system; two preionizers, an MHD generator, and an MHD accelerator. A thermodynamic cycle analysis of the hypothesized MHD energy-bypass system on an existing supersonic turbojet engine was completed. In addition, a detailed thermodynamic, plasmadynamic, and electromagnetic analysis was combined to offer a single, comprehensive model to describe more fully the proper plasma flows and magnetic fields required for successful operation of the MHD energy bypass system. The unique contribution of this research involved modeling the current density, temperature, velocity, pressure, electric field, Hall parameter, and electrical power throughout an annular MHD generator and an annular MHD accelerator taking into account an external magnetic field within a moving flow field, collisions of electrons with neutral particles in an ionized flow field, and collisions of ions with neutral particles in an ionized flow field (ion slip). In previous research, the ion slip term has not been considered. Detailed thermodynamic cycle analysis of an annular MHD generator and an annular MHD accelerator revealed that including the ion slip term to the generalized Ohm's Law decreased the needed magnetic fields and conductivity levels as compared to previous research. For the MHD generator, the needed magnetic fields decreased from 5 T to 3 T for all flight speeds studied (Mach 7, 5, and 3). The conductivity levels required for the ionized airflow within the MHD generator at 3 T decreased from 11 mhos/m to 9 mhos/m for a flight speed of Mach 7 and remained the same for Mach 5 and 3. For the MHD accelerator, the needed magnetic fields decreased from 5 T to 3 T for flight speeds of Mach 7 and 5, and decreased from 3 T to 1.5 T for a flight speed of Mach 3. The conductivity levels required for the ionized airflow within the MHD accelerator (at 3 T) decreased from 2.6 mhos/m to 1.1 mhos/m for a flight speed of Mach 7 and remained the same for Mach 5 and 3. The MHD energy-bypass system model showed that it is possible to expand the operating range of a supersonic jet engine from a maximum of Mach 3.5 to a maximum of Mach 7. The inclusion of ion slip within the analysis further showed that it is possible to 'drive' this system with maximum magnetic fields of 3 T and with maximum conductivity levels of 11 mhos/m. These operating parameters better the previous findings of 5 T and 10 mhos/m, and reveal that taking into account collisions between ions and neutral particles within a weakly ionized flow provides a more realistic model with added benefits of lower magnetic fields and conductivity levels especially at the higher Mach numbers.
Download or read book Analysis of an Unseeded Nonequilibrium MHD Accelerator Concept for Hypersonic Propulsion Ground Testing Applications written by Gloyd A. Simmons and published by . This book was released on 1992 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book U S Government Research Reports written by and published by . This book was released on 1964 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 01 2727 01 2812 written by and published by . This book was released on 2001 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Research and Technology Program Digest Flash Index written by and published by . This book was released on 1967 with total page 794 pages. Available in PDF, EPUB and Kindle. Book excerpt:
