Review of combustion stabilization for hypersonic airbreathing propulsion

Inverse design and Mach 6 experimental investigation of a pressure controllable bump

A finite point method for solving compressible flow problems involving moving boundaries and adaptivity is presented. The numerical methodology is based on an upwind-biased discretization of the Euler equations, written in arbitrary Lagrangian–Eulerian form and integrated in time by means of a dual-time steeping technique. In order to exploit the meshless potential of the method, a domain deformation approach based on the spring network analogy is implemented, and h-adaptivity is also employed in the computations. Typical movable boundary problems in transonic flow regime are solved to assess the performance of the proposed technique. In addition, an application to a fluid–structure interaction problem involving static aeroelasticity illustrates the capability of the method to deal with practical engineering analyses. The computational cost and multi-core performance of the proposed technique is also discussed through the examples provided.

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A meshless finite point method for three‐dimensional analysis of compressible flow problems involving moving boundaries and adaptivity

The influence of the elastic vibration of the carrier to the aerodynamics of the external store in air-launch-to-orbit process

Meshless methods are attractive for simulating moving body problems The selection of the stencils over the domain for the meshless solver is crucial for the method to be competitive with established computational fluid dynamics techniques Stencil selection is relatively straightforward if the point distributions are isotropic in nature, however, this is rarely the case in computations that solve the Navier–Stokes equations In this paper, a fully automatic method of selecting the stencils from anisotropic point distributions, which are obtained from overlapping structured grids, is outlined The original connectivity and the concept of a resolving direction are used to help construct good quality stencils with limited user input

Semi-meshless stencil selection for anisotropic point distributions

The study of separation dynamics of a missile from a fighter aircraft is a prime requirement to ensure the safety of the aircraft before flight testing the missile. An integrated store-separation-dynamics suite has been developed and applied to study the separation of an air-to-air missile from a fighter aircraft. The suite consists of a preprocessor to generate connectivity using overlapped unstructured grids, a three-dimensional grid-free Euler solver to obtain aerodynamic forces and moments on the missile and a six-degrees-of-freedom solver to integrate the equations of motion. A quasi-steady approach has been used to simulate the separation dynamic of rail-launched missile. The motion of the missile guided by the rail launcher has been modeled using constrained-force method and implemented in the six-degrees-of-freedom code. The surface transpiration boundary condition has been incorporated in the Euler solver to mimic the aerodynamic damping and the relative motion of the missile with respect to the ...

Separation Dynamics of Air-to-Air Missile Using a Grid-Free Euler Solver

I N THE history of space exploration, rockets were the only flight vehicles available for transportation such as Earth orbital missions for placing satellites, interplanetary flights, and military missions such as Intermediate Range Ballistic Missiless and Intercontinental Ballistic Missile. Most of these rockets flew a oneway mission of transportation from Earth to the destination and, upon completion of the mission, were either lost in space or fell back to Earth as debris, and hence were nonrecoverable. The cost associated with launching these flight vehicles and the imposing technological challenges, though considered as highly mature as of the present day, were overwhelmingly large. The U.S. Space Shuttle of and the Russian Buran/Energiya were designed and operated as the only reusable flyingmissions that couldmake several sorties between the Earth and the flight to orbit [1]. However, huge operating andmaintenance costs associated with each of these missions, and the inexorable reliability and safety issues, gradually shelved them as unacceptable due to the present-day design philosophy of “low-cost access to space.”Hence, next-generation space exploration required a different class of flight vehicles that was required to be cost efficient and fully reusable. In this realm, the hypersonic airbreathing propulsion system based on a supersonic combustion ramjet (SCRAMJET) was envisaged as the key technology platform for possible realization of the reusable launch vehicle (RLV) in full mission mode, which could perform orbital flights similar to that of spacecraft flown by a rocket system, although with logistics akin to that of an airliner, as on a day-to-day basis [2]. Active flow control of hypersonic flight vehicles forms a crucial design requirement for hypersonic research and technology development. The futuristic RLV concepts, such as the hypersonic cruise vehicle (HSCV) based on the SCRAMJET engine, require complex active flow control techniques that use new multidisciplinary and evolutionary physical mechanisms, such as electromagnetic and plasma discharge flow control, right from launch phase to touchdown. Hence, there is a need and demand to develop a multidisciplinary numerical tool considering the pertinent multiphysics environment for addressing research and development needs, as well as for analysis of various hypersonic flow control problems. A schematic of the hypersonic cruise vehicle configuration based on the RLV concept is shown in Fig. 1. At hypersonic speeds, since the angle of the nose oblique shock is narrow, the entire forebody can be used for compressing the air, and hence forms part of the scramjet engine intake. Due to this, the intake characteristics are strongly coupled to the forebody shape of the HSCV; hence, the forebody is highly design optimized to provide adequate air ram compression and mass capture at the inlet. The exhaust duct of the HSCV scramjet engine is shaped as a nozzle having a considerable length, and it forms part of the HSCV aftbody. The nozzle provides adequate expansion of the combusted gases, which in turn provides thrust to the vehicle. It can be observed that there is a tight coupling of airframe with the propulsion system, and the flight conditions influence the propulsive performance, which in turn affects the aerodynamic performance of the vehicle as a whole, and hence necessitates an integrated aeropropulsive design approach. One of themain challenges encountered in theHSCVdesign is that an adequatemass flow rate should be captured at the inlet and the inlet should start. During offdesign flight conditions, the air mass captured by the air intake might drastically reduce, which can result in flameout and thrust loss. To counter the technical challenges of the HSCV design, such as the subcritical air-intakemass flow rate, high forebody heat flux rates, active thermal management, onboard power generation, thrust augmentation, etc., Vladimir Freighstadt of the Leninetz Holding Company inRussia proposed a novelAJAXvehicle concept [3] in the late 1980s. The AJAX concept hypersonic cruise aircraft was proposed to fly in the mesosphere (50–80 km altitude range) and incorporated various novel technologies based on plasma generation, magnetohydrodynamics (MHD) flow control systems, MHD power generation for controlling and augmenting the hypersonic flow, as well as for thermal management schemes [4–6]. The concept was conceived to use the existing adverse hypersonic environment around the vehicle toward its advantage. The AJAX concept made extensive utilization of MHD-based flow control techniques, where the fluid that was preionized and made electrically conducting was easily manipulated by an externally applied magnetic field. Hence, the hypersonic flowfield could be easily modified for convenience, even at offdesign flight conditions, by application of a suitable magnetic field. Due to the use of various onboard MHD subsystems, such as the MHD-controlled inlet or MHD generator and MHD accelerator, the hypersonic ramjet engine is referred to as the magnetoplasma chemical engine, or MPCE. The schematic of the AJAX concept HSCV [6,7] is shown in Fig. 2. It has a waverider type of forebody design, followed by a flat upper surface to the body end, and it houses the MPCE along the midsection of the lower surface. The MHD generator shown in the figure inhibits the mass flow rate by application of a suitable magnetic field, thereby generating electric current. The hydrocarbon endothermic fuel is converted into the hydrogenenriched mixture and fed into the plasma-stabilized combustor for thermochemical reaction, and it sets on the combustion process. The exhaust products of combusted gas when entering the nozzle region are further accelerated using the MHD accelerator for providing additional thrust. The power source for theMHDaccelerator is drawn from the electricity produced by the MHD generator at the inlet. Since the oncoming air is preionized at the nose region of the HSCV, the overall drag of the vehicle is also reduced significantly. The ionizer housed at the nose region is a microwave beam generator that gets its power supply fromMHDgenerator. As adequate power is generated within the MPCE to solve the high-energy needs of the Received 26 January 2016; revision received 5 May 2016; accepted for publication 16 May 2016; published online 24 June 2016. Copyright © 2016 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. Copies of this paper may be made for personal and internal use, on condition that the copier pay the per-copy fee to the Copyright Clearance Center (CCC). All requests for copying and permission to reprint should be submitted to CCC at www.copyright.com; employ the ISSN 0022-4650 (print) or 1533-6794 (online) to initiate your request. *Directorate of Computational Dynamics; bals.cfd@gmail.com (Corresponding Author). Directorate of Computational Dynamics.

Magnetohydrodynamic Flow Control of a Hypersonic Cruise Vehicle Based on AJAX Concept

Grid-free solver has the ability to solve complex multi-body industrial problems with minimal effort. Grid-free Euler solver has been applied to number of multi-body aerospace vehicles using Chimera clouds of points including flight vehicle with fin deflection, nose fairing separation of hypersonic launch vehicle. A preprocessor has been developed to generate connectivity for multi-bodies using overlapped grids. Surface transpiration boundary condition has been implemented to model aerodynamic damping and to impose the relative velocity of moving components. Dynamic derivatives are estimated with reasonable accuracy and less effort using the grid-free Euler solver with the transpiration boundary condition. Further, the grid-free Euler solver has been integrated with six-degrees of freedom (6-DOF) equations of motion to form store separation dynamics suite which has been applied to obtain the trajectory of a rail launch air-to-air-missile from a complex fighter aircraft. Defence Science Journal, 2010, 60(6), pp.653-662 , DOI:http://dx.doi.org/10.14429/dsj.60.583

http://www.publications.drdo.gov.in/ojs/index.php/dsj/article/download/583/304

Development of Three-dimensional Grid-free Solver and its Applications to Multi-body Aerospace Vehicles

Prediction of flight characteristics of a store in the vicinity of an aircraft is vitally important for ensuring the safety of the aircraft and effectiveness of the store to meet the mission objective. Separation dynamics of an agile air-to-air-Missile from a fighter aircraft is numerically simulated using an integrated store separation dynamics suite. Chimera cloud of points along with a grid-free Euler solver is used to obtain aerodynamic force on the missile and the force is integrated using a rigid body dynamics code to obtain the missile position. In the present work, the suite is applied to a flight test case and sensitivity of trajectory variables on launch parameters is studied. Further, the results of the suite are compared with the flight data. The predicted body rates and Euler angles of missile compare well with the flight data.

https://publications.drdo.gov.in/ojs/index.php/dsj/article/download/11480/6083

Separation Dynamics of Air-to-Air Missile and Validation with Flight Data

In the present study, a three dimensional flowsolver is indigenously developed to numerically simulate hypervelocity thermal and chemical non equilibrium reactive air flow past flight vehicles. The two-temperature, five species, seventeen reactions, thermo-chemical non equilibrium, non-ionizing, air-chemistry model of Park is implemented in a compressible viscous code CERANS and solved in the finite volume framework. The energy relaxation is addressed by a conservation equation for the vibrational energy of the gas mixture resulting in the evaluation of its vibrational temperature. The AUSM-PW+ numerical flux function has been used for modeling the convective fluxes and a central differencing approximation is used for modeling the diffusive fluxes. The flowsolver had been validated for specifically chosen test cases with inherent flow complexities of non-ionizing hypervelocity thermochemical nonequilibrium flows and results obtained are in good agreement with results available in open literature.

K. Anandhanarayanan

Papers

Separation Dynamics of Air-to-Air Missile Using a Grid-Free Euler Solver

Magnetohydrodynamic Flow Control of a Hypersonic Cruise Vehicle Based on AJAX Concept

Development of Three-dimensional Grid-free Solver and its Applications to Multi-body Aerospace Vehicles

Separation Dynamics of Air-to-Air Missile and Validation with Flight Data

Development of a Thermo-chemical Non-equilibrium Solver for Hypervelocity Flows