A number of chemical-kinetic problems related to phenomena occurring behind a shock wave surrounding an object flying in the earth atmosphere are discussed, including the nonequilibrium thermochemical relaxation phenomena occurring behind a shock wave surrounding the flying object, problems related to aerobraking maneuver, the radiation phenomena for shock velocities of up to 12 km/sec, and the determination of rate coefficients for ionization reactions and associated electron-impact ionization reactions. Results of experiments are presented in form of graphs and tables, giving data on the reaction rate coefficients for air, the ionization distances, thermodynamic properties behind a shock wave, radiative heat flux calculations, Damkoehler numbers for the ablation-product layer, together with conclusions.

Review of chemical-kinetic problems of future NASA missions, II: Mars entries

The increasing complexity of engineering systems has sparked increasing interest in multidisciplinary optimization (MDO). This paper presents a survey of recent publications in the field of aerospace where interest in MDO has been particularly intense. The two main challenges of MDO are computational expense and organizational complexity. Accordingly the survey is focused on various ways different researchers use to deal with these challenges. The survey is organized by a breakdown of MDO into its conceptual components. Accordingly, the survey includes sections on Mathematical Modeling, Design- oriented Analysis, Approximation Concepts, Optimization Procedures, System Sensitivity, and Human Interface. With the authors'' main expertise being in the structures area, the bulk of the references focus on the interaction of the structures discipline with other disciplines. In particular, two sections at the end focus on two such interactions that have recently been pursued with a particular vigor: Simultaneous Optimization of Structures and Aerodynamics, and Simultaneous Optimization of Structures Combined With Active Control.

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Multidisciplinary Aerospace Design Optimization: Survey of Recent Developments

Review of preconditioning methods for fluid dynamics

Stagnation-point radiative heating rate expressions are presented for use in air and an approximate Martian atmosphere consisting of 97 percent CO2 and 3 percent N2 Thermochemical equilibrium is assumed throughout The flight conditions and body dimensions that are modeled are representative of both manned and unmanned missions to Mars and return to earth Comparisons between the heating rates computed using the expressions presented here and independent computations yielded maximum differences of about 20 to 30 percent

Stagnation-point radiative heating relations for earth and Mars entries

Numerical sensitivity analysis for aerodynamic optimization: A survey of approaches

A new computer model for the prediction of the trajectory and thermal behavior of high altitude balloons has been developed. In accord with flight data, the model permits radiative emission and absorption of the lifting gas and daytime gas temperatures above that of the balloon film. It also includes ballasting, venting, and valving. Predictions obtained with the model are compared with flight data and newly discovered features are discussed.

New thermal and trajectory model for high-altitude balloons

An inverse numerical technique for designing transonic airfoils having a prescribed pressure distribution is presented. The method uses the full potential equation, inverse boundary conditions, and Cartesian coordinates. It includes simultaneous airfoil update and utilizes a direct-inverse approach that permits a logical method for controlling trailing edge closure. The method can also be used for the analysis of flowfields about specified airfoils. Comparison with previous results shows that accurate results can be obtained with a Cartesian grid. Examples show the application of the method to design aft-cambered and other airfoils specifically for transonic flight.

Transonic airfoil analysis and design using Cartesian coordinates

Various electron impact ionization models in conjunction with a quasi-equilibrium electron temperature model have been investigated and applied to the stagnation region of a hypothetical 2.3 m nose radius Martian return AOTV. For the conditions considered, U = 12 km/sec at 80 km, both multi-temperature inviscid and viscous results indicate that a two-step ionization impact model predicts ionization distances in agreement with experimental data, that nonequilibrium chemistry and radiation effects are important throughout the stagnation zone, and that the quasi-equilibrium electron temperature model is reasonable. Also, using a non-grey emission-absorption radiation step model, it is shown that nonequilibrium causes a reduction in radiative heating from that predicted for equilibrium conditions and that compared to an adiabatic wall a cool wall (1650 deg K) results in a 28 to 45 percent reduction in radiative heating due to absorption near the wall.

Effect of electron temperature and impact ionization on Martian return AOTV flowfields

The quasianalytical approach is developed to compute airfoil aerodynamic sensitivity coefficients in the transonic and supersonic flight regimes. Initial investigation verifies the feasibility of this approach as applied to the transonic small perturbation residual expression. Results are compared to those obtained by the direct (finite difference) approach, and both methods are evaluated to determine their computational accuracies and efficiencies

Determination of aerodynamic sensitivity coefficients based on the transonic small perturbation formulation

The quasi-analytical approach is developed to compute airfoil aerodynamic sensitivity coefficients in the transonic and supersonic flight regimes. Initial investigation verifies the feasibility of this approach as applied to the transonic small perturbation residual expression. Results are compared to those obtained by the direct (finite difference) approach and both methods are evaluated to determine their computational accuracies and efficiencies. The quasi-analytical approach is shown to be superior and worth further investigation.

Leland A. Carlson

Papers

New thermal and trajectory model for high-altitude balloons

Transonic airfoil analysis and design using Cartesian coordinates

Effect of electron temperature and impact ionization on Martian return AOTV flowfields

Determination of aerodynamic sensitivity coefficients based on the transonic small perturbation formulation

Determination of aerodynamic sensitivity coefficients in the transonic and supersonic regimes