Recursos de colección

ETD at Indian Institute of Science (2.518 recursos)

Repository of Theses and Dissertations of Indian Institute of Science, Bangalore, India. The repository has been developed to capture, disseminate and preserve research theses of Indian Institute of Science.

Aerospace Engineering (aero)

Mostrando recursos 1 - 20 de 197

  1. Experimental Investigation Of Aerodynamic Interference Heating Due To Protuberances On Flat Plates And Cones Facing Hypersonic Flows

    Kumar, Chintoo Sudhiesh
    With the age of hypersonic flight imminent just beyond the horizon, researchers are working hard at designing work-arounds for all the major problems as well as the minor quirks associated with it. One such issue, seemingly innocuous but one that could be potentially deadly, is the problem of interference heating due to surface protuberances. Although an ideal design of the external surfaces of a high-speed aircraft dictates complete smoothness to reduce drag, this is not always possible in reality. Control surfaces, sheet joints, cable protection pads etc. generate surface discontinuities of varying geometries, in the form of both protrusions as...

  2. Nature Inspired Optimization Techniques For Flood Assesment And Land Cover Mapping Using Satellite Images

    Senthilnath, J
    With the advancement of technology and the development of more sophisticated remote sensing sensor systems, the use of satellite imagery has opened up various fields of exploration and application. There has been an increased interest in analysis of multi-temporal satellite image in the past few years because of the wide variety of possible applications of in both short-term and long-term image analysis. The type of changes that might be of interest can range from short-term phenomena such as flood assessment and crop growth stage, to long-term phenomena such as urban fringe development. This thesis studies flood assessment and land cover...

  3. On The Effect Of Material Uncertainty And Matrix Cracks On Smart Composite Plate

    Umesh, K
    Recent developments show the applications of smart structure in different engineering fields. Smart structures can be used for shape and vibration control, structural health monitoring etc. Smart materials can be integrated to composite structure to enhance its abilities. Fiber reinforced composites are the advanced materials of choice in aerospace applications due to its high strength and stiffness, light weight and ability to tailor according to the design requirements. Due to complex manufacturing process and varying operating conditions, composites are susceptible to variation in material properties and damages. The present study focuses on the effect of uncertainties in material properties and...

  4. Multi-Agent Positional Consensus Under Various Information Paradigms

    Das, Kaushik
    This thesis addresses the problem of positional consensus of multi-agent systems. A positional consensus is achieved when the agents converge to a point. Some applications of this class of problem is in mid-air refueling of the aircraft or UAVs, targeting a geographical location, etc. In this research work some positional consensus algorithms have been developed. They can be categorized in two part (i) Broadcast control based algorithm (ii) Distributed control based algorithm. In case of broadcast based algorithm control strategies for a group of agents is developed to achieve positional consensus. The problem is constrained by the requirement that every...

  5. UAV Group Autonomy In Network Centric Environment

    Suresh, M
    It is a well-recognized fact that unmanned aerial vehicles are an essential element in today’s network-centric integrated battlefield environment. Compared to solo UAV missions, multiple unmanned aerial vehicles deployed in co-operative mode, offer many advantages that has motivated UAV researchers all over the world to evolve concept of operations that aims in achieving a paradigm shift from traditional ”dull” missions to perform ”dirty” and ”dangerous” missions. In future success of a mission will depend on interaction among UAV groups with no interaction with any ground entity. To reach this capability level, it is necessary for researchers, to first understand the various...

  6. LES Study Of Free Jets And Jets Impinging On Cuboidal Cavity

    Varadharajan, Ramanathan
    Numerical solutions based on explicit filtered LES for computing turbulent flow field, of free round jets and impinging round jet on cuboidal cavities, are presented and discussed in this dissertation work. One-parameter fourth-order explicit filter is implemented to account for sub-grid scale effects. Compact difference schemes proposed by Hixon & Turkel involving only bidiagonal matrices is used to evaluate spatial derivatives. Compact schemes with overall fourth order accuracy and eight order accuracy are used in simulating free and impinging jets respectively. Simulations of free round jets are used for validating LES approach. 6 simulations of free round jet, in three levels...

  7. Optimal Guidance Of Aerospace Vehicles Using Generalized MPSP With Advanced Control Of Supersonic Air-Breathing Engines

    Maity, Arnab
    A new suboptimal guidance law design approach for aerospace vehicles is proposed in this thesis, followed by an advanced control design for supersonic air-breathing engines. The guidance law is designed using the newly developed Generalized Model Predictive Static Programming (G-MPSP), which is based on the continuous time nonlinear optimal control framework. The key feature of this technique is one-time backward propagation of a small-dimensional weighting matrix dynamics, which is used to update the entire control history. This key feature, as well as the fact that it leads to a static optimization problem, lead to its computational efficiency. It has also...

  8. Determination Of Isopectral Rotating And Non-Rotating Beams

    Kambampati, Sandilya
    In this work, rotating beams which are isospectral to non-rotating beams are studied. A rotating beam is isospectral to a non-rotating beam if both the beams have the same spectral properties i.e; both the beams have the same set of natural frequencies under a given boundary condition. The Barcilon-Gottlieb transformation is extended, so that it converts the fourth order governing equation of a rotating beam (uniform or non-uniform), to a canonical fourth order eigenvalue equation. If the coefficients in this canonical equation match with the coefficients of the non-rotating beam (non-uniform or uniform) equation, then the rotating and non-rotating beams...

  9. A Residual Based h-Adaptive Strategy Employing A Zero Mean Polynomial Reconstruction

    Patel, Sumit Kumar
    This thesis deals with the development of a new adaptive algorithm for three-dimensional fluid flows based on a residual error estimator. The residual, known as the R –parameter has been successfully extended to three dimensions using a novel approach for arbitrary grid topologies. The computation of the residual error estimator in three dimensions is based on a least-squares based reconstruction and the order of accuracy of the latter is critical in obtaining a consistent estimate of the error. The R –parameter can become inconsistent on three–dimensional meshes depending on the grid quality. A Zero Mean Polynomial(ZMP) which is k–exact, and...

  10. Energy Separation And Lox Separation Studies In Vortex Tubes

    Behera, Upendra
    Vortex Tube (VT) is a simple device having no moving mechanical parts, in which compressed gas at high pressure is injected through one or more tangential nozzles into a vortex chamber resulting in the separation of the inlet flow into two low pressure streams. One of the streams is the peripheral flow that is warmer than the inlet stream while the other is the central (core) flow that is colder than the inlet stream. This separation of the inlet flow into high and low temperature streams is known as temperature or energy separation. It is suggested by many investigators that...

  11. Dynamics Of Water Drops Impacting Onto The Junction Of Dual-Textured Substrates Comprising Hydrophobic And Hydrophilic Portions

    Vaikuntanathan, Visakh
    The research topic of liquid drop interaction with solid surfaces is being actively pursued to gain in-depth understanding of several practical cases such as the impingement of fuel spray droplets on surfaces like combustion chamber walls and piston top of an I.C. engine, heat transfer via spray impingement, ink-jet printing, etc. In most of the cases, the physical and flow properties of the liquid drop/spray may be fixed whereas it may be possible to tune the physical and chemical properties of the solid surface thereby enabling to control the interaction process. The present work belongs to the study of liquid...

  12. LU-SGS Implicit Scheme For A Mesh-Less Euler Solver

    Singh, Manish Kumar
    Least Square Kinetic Upwind Method (LSKUM) belongs to the class of mesh-less method that solves compressible Euler equations of gas dynamics. LSKUM is kinetic theory based upwind scheme that operates on any cloud of points. Euler equations are derived from Boltzmann equation (of kinetic theory of gases) after taking suitable moments. The basic update scheme is formulated at Boltzmann level and mapped to Euler level by suitable moments. Mesh-less solvers need only cloud of points to solve the governing equations. For a complex configuration, with such a solver, one can generate a separate cloud of points around each component, which...

  13. A Synergetic Micromechanics Model For Fiber Reinforced Composites

    Padhee, Srikant Sekhar
    Composite materials show heterogeneity at different length scales. hence concurrent multiscale analysis is the only reliable method to analyze them. But unfortunately there is no concurrent multi-scale strategy that is efficient, and accurate while addressing all kinds of problems. This lack of reliability is partly because there is no micro-mechanical model which inherently keeps all relevent global information with it. This thesis tries to fill this gap. The presented micro-mechanical model not only homogenizes the micro-structure but also keeps the global information with it. Most of the micro-mechanical models in the literature extract the Representative Volume Element (RVE) from the continuum...

  14. Experimental Study On The Impact Of Water Drops On Groove-Textured Surfaces

    Kannan, R
    The interaction of a liquid drop with a solid surface is being actively studied to understand practically encountered scenarios such as the impact of fuel spray droplets onto the walls of engine combustion chamber, the formation of thermal barrier coating on the surfaces of turbine blades, the process of ink-jet printing, etc. The surface topography of solid surface is one of the major parameters influencing the dynamics of drop-surface interaction process. Understanding the precise role of surface topography features such as micro asperities and grooves on the spreading and receding processes of impacting liquid drops is crucial for the improvement...

  15. Modeling And Computation Of Turbulent Nonreacting And Reacting Sprays

    De, Santanu
    Numerical modeling of several turbulent nonreacting and reacting spray jets is carried out using a fully stochastic separated flow (FSSF) approach. As is widely used, the carrier-phase is considered in an Eulerian framework, while the dispersed phase is tracked in a Lagrangian framework following the stochastic separated flow (SSF) model. Various interactions between the two phases are taken into account by means of two-way coupling. Spray evaporation is described using a thermal model with an infinite conductivity in the liquid phase. The gas-phase turbulence terms are closed using the k-� model. In the classical SSF (CSSF) approach the effects of...

  16. Micro-Blast Waves

    Obed Samuelraj, I
    The near field blast–wave propagation dynamics has been a subject of intense research in recent past. Since experiments on a large scale are difficult to carry out, focus has been directed towards recreating these blast waves inside the laboratory by expending minuscule amounts of energy(few joules),which have been termed here as micro–blast waves. In the present study, micro-blast waves are generated from the open end of a small diameter polymer tube (Inner Diameter of 1.3 mm)coated on its inner side with negligible amounts of HMX explosive (~18 mg/m), along with traces of aluminium powder. Experimental, numerical, and analytical approaches have...

  17. Collision Avoidance And Coalition Formation Of Multiple Unmanned Aerial Vechicles In High Density Traffic Environments

    Manathara, Joel George
    This thesis addresses the problems of collision avoidance and coalition formation of multiple UAVs in high density traffic environments, proposes simple and efficient algorithms as solutions, and discusses their applications in multiple UAV missions. First, the problem of collision avoidance among UAVs is considered and deconfliction algorithms are proposed. The efficacy of the proposed algorithms is tested using simulations involving random flights in high density traffic. Further, the proposed collision avoidance algorithms are implemented using realistic six degree of freedom UAV models. The studies in this thesis show that implementation of the proposed collision avoidance algorithms leads to a safer and...

  18. Parametric Analysis Of A Free Piston Stirling Engine For Spacecraft Power Applications With A Radioisotope Heat Source

    Bhaskaran, Ramprasad
    Stirling engines are promising candidates for applications where air breathing engines cannot be used. Self contained engines capable of operating independently of the environment are required to convert thermal energy into electric power, or to perform other necessary functions. These are ideally suited for power generation onboard spacecrafts with radioisotope heat source. These engines can power interplanetary missions to Mars and beyond. The problem of parametric analysis, sensitivity and numerical optimization of Stirling cycle engine is discussed and applied to a specific example of a 2kWe free piston Stirling engine. Stirling cycle simulation programs are generated with emphasis and adaptations...

  19. Packed Bed Gasification-Combustion In Biomass Based Domestic Stoves And Combustion Systems

    Varunkumar, S
    This thesis constitutes fundamental experimental and computational investigations on gasification and combustion in a packed bed of biomass. Packed bed gasification-combustion in counter-current mode is used in two applications -(1) Gasifier stove in reverse downdraft mode (or equivalently, top-lit updraft mode) that constitutes the idea behind efficient and clean burning domestic stoves. (2) Combustion-on moving grate for boiler application, studied widely in Europe. While a large part of the present study is around domestic stoves, a crucial part of the study aims to address the second application as an extension of the approach taken in the first part to clarify...

  20. Experimental Measurement Of Flame Response To Acoustic Oscillations

    Alexander, Sam
    Acoustic instabilities in a combustion chamber arise due to the coupling of acoustic pressure with in-phase heat-release, and are characterized by large amplitude oscillations of one or more natural modes of combustor. Even though an array of studies, both theoretical and experimental, has been conducted by a number of authors in this field to extract the flame response, most of these are based on kinematic flame models. In this dissertation, an experimental study of a subsonic flame's intrinsic response to acoustic pressure perturbations is performed for the case of a tube closed at one end and the other end opened...

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