This paper considers 
                  the numerical optimization of a double ramp 
                  scramjet inlet using magnetohydrodynamic (MHD) 
                  effects together with inlet ramp angle changes. 
                  The parameter being optimized is the mass 
                  capture at the throat of the inlet, such that 
                  spillage effects for less than design Mach 
                  numbers are reduced. The control parameters for 
                  the optimization include the MHD effects in 
                  conjunction with ramp angle changes. To enhance 
                  the MHD effects different ionization scenarios 
                  depending upon the alignment of the magnetic 
                  field are considered. The flow solution is based 
                  on the Advection Upstream Splitting Method 
                  (AUSM) that accounts for the MHD source terms as 
                  well. A numerical 
                  Broyden-Flecher-Goldfarb-Shanno- (BFGS-) based 
                  procedure is utilized to optimize the inlet mass 
                  capture. Numerical validation results compared 
                  to published results in the literature as well 
                  as the outcome of the optimization procedure are 
                  summarized to illustrate the efficacy of the 
                  approach.

Kamesh Subbarao

Jennifer D. Goss

Combined Magnetohydrodynamic and Geometric Optimization of a Hypersonic Inlet

This paper compares the analysis of systems from two different perspectives: an energy-based focus and an exergy-based focus. A complex system was simply modeled as interacting thermodynamic systems to illustrate the differences in analysis methodologies and results. The energy-based analysis had combinations of calculated states that are infeasible. On the other hand, the exergy-based analyses only allow feasible states. More importantly, the exergy-based analyses provide clearer insight to the combination of operating conditions for optimum system-level performance. The results strongly suggest changing the analysis/design paradigm used in aerospace engineering from energy-based to exergy-based. This methodology shift is even more critical in exploratory research and development where previous experience may not be available to provide guidance. Although the models used herein may appear simplistic, the message is very powerful and extensible to higher-fidelity models: the 1st Law is only a necessary condition for design, whereas the 1st and 2nd Laws provide the sufficiency condition.

John H. Doty

José A. Camberos

David J. Moorhouse

Benefits of Exergy-Based Analysis for Aerospace Engineering Applications—Part I

This paper introduces a new set of orbits, the &#x201C;Repeated Shadow Track Orbits.&#x201D; In these orbits, the shadow of a spacecraft on the Earth visits the same locations periodically every desired number of days. The <svg style="vertical-align:-3.13504pt;width:14.6625px;" id="M1" height="14.2375" version="1.1" viewBox="0 0 14.6625 14.2375" width="14.6625" xmlns="http://www.w3.org/2000/svg">
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</svg> perturbation is utilized to synchronize the spacecraft shadow motion with both the Earth rotational motion and the Earth-Sun vector rotation. Motivation for the design of new shadow track orbits comes from the need to save energy. The general mathematical model to design a Repeated Shadow Track Orbit (RSTO) is presented within this paper. RSTOs&#x27; conditions are formulated and numerically solved. Results show the feasibility of RSTOs. An optimization process is also developed to maximize the shadow duration over a given site. A Genetic Algorithm (GA) technique is utilized for optimization.

Ahmed Gad

Ossama Abdelkhalik

Repeated Shadow Track Orbits for Space-SunSetter Missions

A new approach to optimize the geometry of a turbine airfoil by simultaneously designing multiple 2D sections of the airfoil is presented in this paper. The complexity of 3D geometry modeling is circumvented by generating multiple 2D airfoil sections and constraining their geometry in the radial direction using first- and second-order polynomials that ensure smoothness in the radial direction. The flow fields of candidate geometries obtained during optimization are evaluated using a quasi-3D, inviscid, CFD analysis code. An inviscid flow solver is used to reduce the execution time of the analysis. Multiple evaluation criteria based on the Mach number profile obtained from the analysis of each airfoil cross-section are used for computing a quality metric. A key contribution of the paper is the development of metrics that emulate the perception of the human designer in visually evaluating the Mach Number distribution. A mathematical representation of the evaluation criteria coupled with a parametric geometry generator enables the use of formal optimization techniques in the design. The proposed approach is implemented in the optimal design of a low-pressure turbine nozzle.

Sanjay Goel

Turbine Airfoil Optimization Using Quasi-3D Analysis Codes

We address the design of a 
            flight vehicle from the viewpoint of a system of 
            systems and we discuss the integration of the 
            individual technical disciplines. Then a conceptual 
            fundamental methodology and tools required for the 
            analysis, design, and optimization of aerospace 
            vehicles in terms of the efficient use of on-board 
            energy are discussed. This suggests changing the 
            design paradigm to the optimization of a system of 
            energy systems. We propose a foundation for 
            system-level design with optimization based on minimum 
            exergy destruction.

Systems Engineering in Terms of Exergy

A fully 3D failure model to predict damage in composite structures subjected to multiaxial loading is presented in this paper. The formulation incorporates shear nonlinearities effects, irreversible strains, damage and strain rate effects by using a viscoplastic damageable constitutive law. The proposed formulation enables the prediction of failure initiation and failure propagation by combining stress-based, damage mechanics and fracture mechanics approaches within an unified energy based context. An objectivity algorithm has been embedded into the formulation to avoid problems associated with strain localization and mesh dependence. The proposed model has been implemented into ABAQUS/Explicit FE code within brick elements as a userdefined material model. Numerical predictions for standard uniaxial tests at element and coupon levels are
presented and discussed.

Maur&#xed;cio V. Donadon

S&#xe9;rgio Frascino M. de Almeida

Mariano A. Arbelo

Alfredo R. de Faria

A Three-Dimensional Ply Failure Model for Composite Structures

An airfoil subjected to two-dimensional incompressible inviscid flow is considered.
The airfoil is supported via a translational and a torsional springs. The aeroelastic
integro-differential equations of motion for the airfoil are reformulated into a system of
six first-order autonomous ordinary differential equations. These are the simplest and
least number of ODEs that can present this aeroelastic system. The differential equations are then used for the bifurcation analysis of an airfoil with a structural nonlinearity in the pitch direction. Sample bifurcation diagrams
showing both stable and unstable limit cycle oscillation are presented. The types of
bifurcations are assessed by evaluating the Floquet multipliers. For a specific case, a
period doubling route to chaos was detected, and mildly chaotic behavior in a narrow
range of velocity was confirmed via the calculation of the Lyapunov exponents.

H. Alighanbari

S. M. Hashemi

Derivation of ODEs and Bifurcation Analysis of a Two-DOF Airfoil Subjected to Unsteady Incompressible Flow

This publication presents the architecture integration and implementation of various modules in Sparta framework. Sparta is a trajectory engine that is hooked to an Online Analytical Processing (OLAP) database for Multi-dimensional analysis capability. OLAP is an Online Analytical Processing database that has a comprehensive list of atmospheric entry probes and their vehicle dimensions, trajectory data, aero-thermal data and material properties like Carbon, Silicon and Carbon-Phenolic based Ablators. An approach is presented for dynamic TPS design. OLAP has the capability to run in one simulation several different trajectory conditions and the output is stored back into the database and can be queried for appropriate trajectory type. An OLAP simulation can be setup by spawning individual threads to run for three types of trajectory: Nominal, Undershoot and Overshoot trajectory. Sparta graphical user interface provides capabilities to choose from a list of flight vehicles or enter trajectory and geometry information of a vehicle in design. DOTNET framework acts as a middleware layer between the trajectory engine and the user interface and also between the web user interface and the OLAP database. Trajectory output can be obtained in TecPlot format, Excel output or in a KML (Keyhole Markup Language) format. Framework employs an API (application programming interface) to convert trajectory data into a formatted KML file that is used by Google Earth for simulating Earth-entry fly-by visualizations.

Prabhakar Subrahmanyam

High-Fidelity Aerothermal Engineering Analysis for Planetary Probes Using DOTNET Framework and OLAP Cubes Database

We address a dynamic configuration strategy for teams of Unmanned Air Vehicles (UAVs). A team is a collection of UAVs which may evolve through different organizations, called configurations. The team configuration may change with time to adapt to environmental changes, uncertainty, and adversarial actions. Uncertainty comes from the stochastic nature of the environment and from incomplete knowledge of adversary behaviors. To each configuration, there corresponds a set of different properties for the UAVs in the team. The design for the configuration control problem involves a distributed hierarchical control architecture where the properties of the system can be formally analyzed. We do this in the framework of dynamic networks of hybrid automata. We present results from simulation to demonstrate different scenarios for adversarial response.

Mariam Faied

Ihemed Assanein

Anouck Girard

UAVs Dynamic Mission Management in Adversarial Environments

About this journal

International Journal of Aerospace Engineering serves the international aerospace engineering community through the dissemination of scientific knowledge on practical engineering and design methodologies pertaining to aircraft and space vehicles.

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Chief Editor, Professor Zhao, is based at the University of Canterbury and his research interests include applying theoretical, numerical and experimental approaches to study combustion instability, thermoacoustics and aerodynamics.

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International Journal of Aerospace Engineering - Table of contents 2009

International Journal of Aerospace Engineering | Hindawi

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International Journal of Aerospace Engineering serves the international aerospace engineering community through the dissemination of scientific knowledge on practical engineering and design methodologies pertaining to aircraft and space vehicles.

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International Journal of Aerospace Engineering

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International Journal of Aerospace Engineering