Luo Shibin

The MDO Environment for Hypersonic Vehicle System Design and Optimization

*† ‡ § ** †† In this article, a MDO environment (or tool)—HyDOT is developed for airbreathing hypersonic vehicle (AHV) system design and optimization, and relevant AHV MDO applications are summarized. HyDOT integrates the current disciplines analysis codes, and runs on a distributed Lan, which can make it feasible to design AHV interactively. HyDOT adopts a client-server framework with a configuration composed of three subsystem that are User Layer, Analysis Tool Layer, and Data Layer, and with a modular architecture including modules of disciplines analysis, GUI, Visualization, Database, iSIGHT Integrated Optimization, and System Integration. High-fidelity analysis tools are used to acquire aerodynamic, propulsive and structural performance. Two optimization cases for system of AHV with booster are discussed, one case applies all-at-once (AAO) optimization procedure, and the other one applies concurrent sub-space optimization (CSSO) procedure. The results indicate that HyDOT platform is available and benefit to improve the efficiency of the AHV system synthesis. I. Introduction he efforts of overall design of airbreathing hypersonic vehicle (AHV) have been mostly focused on concept design during the early stage, since there are short of appropriate accurate discipline analysis tools, especially for the absence of the effective system synthesis design and optimization method. With the development of aircraft general design technique and computation capability, the level of system synthesis of AHV is increased greatly, and some integrated environments for AHV system synthesis design and optimization are developed. There are some typical integrated environments (or frameworks) for AHV synthesis. For example, the vehicle synthesis code HAVOC which is developed by NASA Ames Research Center can be used to perform AHV shape, size, weight, performance, and cost optimization with the support of high-fidelity propulsion, aerodynamics, structure and aerothermodynamics database. 1,2 Similarly, the AHV synthesis system which is named HOLIST and developed by the Systems Analysis Office (SAO) at NASA Langley Research Center, is a working environment for design, analysis and optimization of AHV by integrating disciplines analysis codes. 3,4 In order to improve the accuracy and efficiency of AHV synthesis, and to consider more complicated disciplines couplings, some integrated environments are combined commercial available Multidisciplinary Design and Optimization (MDO) frameworks such as iSIGHT, AML and ModelCenter which may supply common service functions such as integration, communication and optimization. For example, a conceptual design environment of the High Speed Standoff Missile created by Georgia Tech’sAerospace System Design Laboratory, utilizes iSIGHT software to integrate disciplinary analysis codes. 5 And an integrated modeling environment for the conceptual and preliminary-level design and synthesis of AHV developed by the US Air Force Research Laboratory, utilizes AML software as foundation of design modeling and integration. 6 Similarly, the Integrated Hypersonic Aeromechanics Tool (IHAT) system used for configuration optimization of AHV is developed by the US Naval Systems Group, which utilizes the ModelCenter software to implement the integration and interactive execution. 7-9

Numerical Simulation and Experimental Validation of Shock Oscillations in Hypersonic Vehicle’s Flowpath

Scramjet is a new type of airbreathing hypersonic propulsion systems. Unlike the turbojets that use a turbine to compress air for combustion, the scramjet contains virtually no moving parts, and relies on supersonic forward motion instead for air compression. The advantages a scramjet offer over a rocket engine is that a scramjet draws its oxygen from earth’s atmosphere, unlike a rocket that must carry its oxygen supply. Such, the scramjet craft can be made smaller, lighter and faster, providing much greater range for the same fuel load [1]. So, scramjet becomes preferred engine for hypersonic vehicles [2]. A scramjet normally operates above Mach 4. To get a aircraft to Mach 4, a jet or rocket engine is typically used for the initial acceleration. During boost phase, the inlet is open, and the nozzle is closed, so the flowpath of the hypersonic vehicle forms a blind cavity. Then shock wave oscillations may be appear [3], and this brings serious challenges for structure and flight control design of the vehicle.