bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization Methods in Computational Fluid Dynamics
Authors: Jameson Antony , Ou Kui 
Published: December 2010

AbstractThis chapter discusses the role that computational fluid dynamics (CFD) plays in the design of aircraft. An overview of the design process is provided, covering some of the typical decisions that a design team addresses within a multi‐disciplinary environment. On a very regular basis, trade‐offs between disciplines have to be made where a set of conflicting requirements exist. Within an aircraft development project, we focus on the aerodynamic design problem and review how this process has been advanced, first with the improving capabilities of traditional computational fluid dynamics analyses and then with aerodynamic optimizations based on these increasingly accurate methods. We then review the formulation and application of optimization techniques based on control theory for aerodynamic shape design in both potential flow and inviscid compressible flow. The theory is applied to a system defined by the partial differential equations of the flow, with the boundary shape acting as the control. The Frechet derivative of the cost function is determined via the solution of an adjoint partial differential equation, and the boundary shape is then modified in a direction of descent. This process is repeated until an optimum solution is approached. Each design cycle requires the numerical solution of both the flow and the adjoint equations, leading to a computational cost roughly equal to the cost of two flow solutions. Several case studies are provided, which highlight the benefits of utilizing automatic aerodynamic shape optimization.
Adaptive Mesh and Overlapping Grid Methods
Authors: Henshaw William D. 
Published: December 2010

AbstractAdaptive mesh refinement (AMR) is a technique used in computational fluid dynamics to add fine grid patches to regions of the flow where more resolution is needed, such as near shocks and detonations. AMR can dramatically speed up a computation and/or enable simulations with a much higher effective resolution compared to uniformly refining the grid. Overlapping grids (also known as Chimera or overset grids) are a technique for covering a complex geometry with a set of overlapping structured grids. Overlapping grids can be more easily generated than multi‐block‐structured grids. Efficient numerical schemes can be written for overlapping grids since they are composed of structured grids and Cartesian grids. They are also effective for moving geometry problems such as aircraft store separation, and rotor craft, since the grids can be rapidly regenerated at each time step.
Solution Methods and Acceleration Techniques in Computational Fluid Dynamics (
CFD
)
Authors: Dwight Richard P. , Lucas Peter , Bijl Hester 
Published: December 2010

Abstract
Methods for solving the discretized equations of fluid motion are discussed, with particular reference to efficient methods for solving compressible flow problems to a steady state. A spectrum of algorithms of widely varying efficiency and complexity are considered from explicit single‐stage methods, through Runge–Kutta (RK), implicit methods, defect correction, to multigrid. They are classified with respect to cost per iteration, convergence rate, and memory requirements and compared for a concrete high‐Reynolds number test‐case. Time‐resolved calculations are then considered using the dual‐time framework.
Discontinuous Galerkin Methods
Authors: Shu Chi‐Wang 
Published: December 2010

AbstractIn this article we describe the discontinuous Galerkin method, which is a finite element method incorporating successful shock capturing finite volume techniques such as Riemann solvers, limiters, and total‐variation‐diminishing Runge–Kutta time discretizations, suitable for solving hyperbolic conservation law systems as well as convection‐dominated convection diffusion equations such as the high Reynolds number Navier–Stokes equations.
Optical Flow Visualization
Authors: Kontis Konstantinos , Zare‐Behtash Hossein 
Published: December 2010

AbstractOptical flow visualization techniques rely on the changes in flow density and hence the refractive index of the flow. Through various flow visualization techniques an image of the flow field is obtained which can be either qualitative, quantitative, or even both. The use of the appropriate visualization technique strongly depends on the flow field under investigation and the flow properties sought. The optical visualization techniques described here fall into the following categories: shadowgraphy, schlieren, moiré deflectometry, and interferometry. The optical tomography method which allows for the three‐dimensional reconstruction of the flow using two‐dimensional results is also briefly described.
Pressure and Velocity Measurements
Authors: Telionis Demetri P. , Yang Yihong , Jones Gregory S. , Rediniotis Othon K. 
Published: December 2010

Abstract
Multi‐hole probe (MHP) design is based on the fact that the static pressure varies over a solid surface from the maximum value equal to the stagnation pressure to low values, the order of the base pressure in the wake of the body. In this chapter we describe the basic principles of operation, the construction and the calibration methods of MHPs. A very short discussion of their uses is also given.
Thermal Anemometry: An Introduction and Special Topics
Authors: Andreopoulos Yiannis 
Published: December 2010

AbstractThe basic principles and practices of thermal anemometry are presented and discussed. Modes of operation include constant temperature, constant current, and constant voltage. Models of the transfer function are considered for single and multiple hot‐wire probes which include techniques to measure vorticity, rate of strain, and dissipation rate of kinetic energy in incompressible and compressible flows. The response of hot wires to pitch and yaw variations of the incoming velocity vector is also addressed. Owing to its high‐frequency response, good spatial resolution, and relatively inexpensive hardware acquisition cost, thermal anemometry techniques appear to be widely used in the measurements of time‐dependent flow velocity, mass flux, or temperature.
Laser Doppler Velocimetry
Authors: Tropea Cameron 
Published: December 2010

AbstractThe laser Doppler technique, most frequently referred to as a laser Doppler anemometer (LDA) or laser Doppler velocimeter (LDV), is a wide‐spread technique for point‐wise velocity measurements in a flow with fluid markers. Some decisive advantages of the technique over more conventional probe‐based techniques can be mentioned: non‐intrusiveness, directional sensitivity, high spatial and temporal resolution, and high accuracy. In this chapter the fundamental principles of laser Doppler velocimetry will be introduced, including a discussion of optical arrangements, signal generation, signal processing, and data processing. Particular attention will be given to applications in aerodynamic flows, in which the introduction of tracer particles and the velocity bandwidth of the instrument demand special attention. Also, the challenge of performing point measurements with high spatial resolution in large facilities will be addressed.
Spectroscopic and Scattering Techniques
Authors: Ötügen M. Volkan 
Published: December 2010

AbstractThis chapter reviews techniques that depend on the spectroscopic analysis of scattered laser light by atoms or molecules in a gas. A number of techniques are available today that can provide quantitative information about species concentration, gas density, temperature, pressure, and velocity. In most cases, the measurements are resolved in space and in time. In addition to single‐point measurements, two‐ or three‐dimensional quantitative imaging of the desired flow parameter are possible with some of the techniques. Scattering and spectroscopic methods are non‐intrusive since only the laser beam is present in the measurement environment. Hence, they are well suited for aerodynamics applications, particularly for high‐speed and reacting flows. The measurement techniques discussed here are absorption spectroscopy, Rayleigh scattering, Raman scattering, laser‐induced fluorescence (LIF), and coherent anti‐Stokes Raman scattering (CARS).
Temperature and Heat Transfer Measurements
Authors: Camci Cengiz 
Published: December 2010

AbstractThis chapter deals with the state‐of‐the‐art in temperature and heat transfer measurements that are frequently encountered in Aerospace Engineering. Resistive temperature transducers, thermocouples, bi‐metallic temperature sensors, semi‐conductor diode‐based temperature sensing, liquid crystal thermography, infrared thermography, and pyrometry are discussed in detail. Measurements of convective, conductive, radiative, or total heat transfer rates are often required in aerospace engineering such as atmospheric re‐entry studies, hot‐section component development for gas turbines, ramjet/scramjet development, ballistic missile nose cone development, heat exchanger development, rocket engine combustors, and nozzles. Finally, heat transfer measurements are discussed. Although many illustrations and discussions are used throughout the text, more detailed information in this area can be obtained from the many valuable references provided.
Measurement of Aerodynamic Forces and Moments in Wind Tunnels
Authors: Fan Zhaolin 
Published: December 2010

Abstract
Aerodynamic forces and moments are among the most important data required for flight vehicle performance simulation and design, and such data can be obtained through wind tunnel model tests among other methods. The work described here relates to wind tunnel tests based on relativity and similarity principles. Test models of the studied objects were fabricated in accordance with similarity criteria and connected to a balance and support system fixed on a motion‐controlling mechanism for changing or controlling the attitude angles of the model. This has been installed in the test section of a wind tunnel. When gas flows under test conditions through the wind tunnel section, aerodynamic forces and moments exerted on the model are transferred to the balance and converted into electrical signals. These signals are filtered and amplified by a signal‐conditioning system, sampled by a data acquisition system and then processed to obtain the aerodynamic forces and moments. Other parameters such as total and static pressures, total temperature, and model attitude angle are measured by a pressure transducer, temperature sensor, and angle sensor, respectively. After synthesizing all the measurements, the non‐dimensional aerodynamic force and moment coefficients are obtained and then used for vehicle design and simulation.
Lift, Thrust, and Flight
Authors: Hu Hui , Shyy Wei , Shih Tom I‐P. 
Published: December 2010

AbstractAn overview is provided on forces and motions and their generation that are relevant to flight. First, Newton's laws of motion are outlined. Next, the four types of forces that are involved in flight – weight, lift, drag, and thrust – and their interrelationships are described. This is followed by an introduction on how natural flyers/swimmers generate lift and thrust to fly/swim through flapping wings/fins. The understanding of these flight mechanisms is important to the development of micro aerial vehicles, which operate at relatively low Reynolds numbers and where lift generation typically produces unsteady flows. Afterwards, a discussion is given on how humankind achieves flight through the airplane, where the weight of the payload, the flight speed, and the range of flight can be orders of magnitudes higher than natural flyers. For the airplane, the wings generate most of the lift, and the propulsive devices generate the thrust. The propulsive devices summarized include propellers, turbojets, turbofans, ramjets, scramjets, and rockets – all of which produce thrust by ensuring that the momentum exiting the propulsive device far exceeds the momentum entering the propulsive device.
An Overview of Gas Turbine Engines
Authors: Reddy Dhanireddy R. 
Published: December 2010

Abstract
Gas‐turbine engines are widely used for aircraft propulsion because of their high efficiency in the power range of interest. This chapter presents an overview of gas‐turbine engines, including a discussion of the thermodynamic cycle and definitions of component and system efficiencies relevant to the performance of the engines. Also presented is how gas‐turbine engines are classified as turbojet, turbofan, turboprop, propfan, and ramjet based on how thrust is generated for propulsion. For each of these types of gas‐turbine engines, the distinguishing features are highlighted. Finally, application of supersonic combustion in a ramjet, known as a scramjet, for propulsion in hypersonic speed regime is outlined.
Internal Air and Lubrication Systems
Authors: Johnson Bruce V. 
Published: December 2010

AbstractThe internal air and lubrication systems of gas turbines are described. The internal air system of a gas turbine distributes the air extracted from the main gas path at several axial locations in the compressors to ventilate and cool the engine components and to provide an axial pressure balance on the rotating components to control the axial loads on the bearings. Special fluid engineering and heat transfer technologies that are required for this task are described, including transfer of air through rotating orifices, transfer of the blade cooling air from passages in the engine case to the rotating turbine disks, cooling compressor disk cavities, controlling the sealing flow in the compressor, and controlling the ingestion of combusted gases from the turbine stages into the turbine disk cavities. The lubrication system provides pressurized oil to the bearing compartments that also receive buffer air and returns the oil‐air mixtures to the oil‐air separators and the oil reservoir.
Gas Turbine Engines: Seals
Authors: Chupp Raymond E. , Hendricks Robert C. , Steinetz Bruce M. 
Published: December 2010

Abstract
In turbomachines, seals control clearances. Excessive clearances lead to losses in cycle efficiency, flow instabilities, and hot gas ingestion into disk cavities. Insufficient clearances limit coolant flows and cause interface rubbing, possible overheating of downstream components, and damage interfaces; thus limiting component life. Clearance control is often the most cost effective method to enhance system performance. Advanced concepts and proper material selection continue to play important roles in maintaining interface clearances to enable the system to meet design goals. This chapter presents an overview of sealing in turbomachines.
The Scramjet Engine: Basic and Combined Cycles
Authors: Segal Corin 
Published: December 2010

Abstract
The supersonic‐combustion ramjet (scramjet) is a cycle similar to the basic ramjet with the exception that the airflow remains, at least in certain engine regions, supersonic. The short residence time of the order of milliseconds for a full size engine, imposes severe technological requirements for fuel injection, mixing, and combustion to efficiently release heat and produce thrust. The engine is suitable for flight in excess of Mach 6 when due to the low angle of the ensuing shock waves, the engine becomes highly integrated with the vehicle. The following broadly describes the operation of the scramjet engine and the differences between this and the subsonic ramjet device. Given the range of flight speeds travelled by a hypersonic vehicle, the scramjet will operate along other cycles in a closely couple fashion; several combined cycled concepts are also described.
Emerging Air‐Breathing Propulsion Technologies
Authors: Reddy Dhanireddy R. , Blankson Isaiah 
Published: December 2010

AbstractThis chapter presents emerging trends in airbreathing propulsion technology development based on the technology roadmaps of leading government research organizations addressing national priorities related to engine efficiency, pollutant emissions, noise, reliability, and safety. Technologies and concepts relevant to each of the speed regimes, ranging from subsonic to hypersonic mach numbers that need to be developed and investigated to overcome existing and anticipated barriers, as well as enable commercially viable flight operations, especially at high speeds, are highlighted along with the time frames planned for these developments over the next 25 years. In addition, some of the unconventional research concepts that require sufficient time to understand and overcome engineering challenges of making these concepts practical are also presented, including a few examples such as the exoskeletal engine, the AJAX‐inspired MHD‐controlled turbojet, and the ATREX engine.
Rocket Propulsion: Basic Concepts and Introduction
Authors: Thakre Piyush 
Published: December 2010

Abstract
Rocket propulsion is of vital importance for space travel and for launching satellites into orbits around the earth. It is also instrumental in military applications. Rocket propulsion is a class of jet propulsion that produces thrust by ejecting burned propellant. The thrust is generated on the basis of Newton's third law of motion. Rocket propulsion systems can be broadly classified according to the type of energy source (chemical, solar, electric, or nuclear). The most commonly used rockets are solid propellant rocket motors and liquid propellant rocket engines. This chapter provides an introduction to rocket propulsion by covering the overall classification, basic concepts, and rocket equations. Different types or rocket nozzle designs, the concept of multistaging, and other issues are also presented.
Historical Overview and Solid Rocket Motor Fundamentals
Authors: Geisler Robert L. , Frederick Robert A. , Giarra Matthew 
Published: December 2010

AbstractA technical and historical overview of solid rocket motors (SRMs) is presented. Typical SRM applications are identified, and the principles of SRM operation are described. Common ranges of operating conditions are described, including internal temperatures, pressures, and so on. Several major components of typical SRMs (case, grain, nozzle, and igniter) and the unique design challenges associated with each are discussed in some detail. The performance parameters used in SRM analysis are defined, and some modern analysis tools are identified and discussed. Finally, a brief history of American solid rocketry is given, including the motivations for and developments of some of the scientific and engineering milestones that have enabled the modern era of solid propulsion. The historical relevancies of several notable solid rockets are described as well.
Solid Propulsion: Motor Interior Ballistics – Modeling and Design
Authors: Jackson Thomas L. , Austin Joanna M. 
Published: December 2010

AbstractUnderstanding the interior ballistic characteristics of solid rocket motors is a daunting task for the motor designer because of the large number of coupled performance parameters. The performance parameters depend upon the internal ballistic properties of the motor, such as propellant burn rate. The designer has two basic options for developing new motors, built‐and‐test, or using a combination of numerical simulation, empiricalism, and small‐scale testing for validation, collectively known as virtual engineering. Virtual engineering, which requires appropriate models for the propellant, chamber, nozzle, and plume regions, is rapidly becoming the standard tool for designing new motors. We highlight some modern developments of physics‐based models used in virtual engineering, and comment on current trends.
Liquid Propulsion: Historical Overview, Fundamentals, and Classifications of Liquid Rocket Engines
Authors: Kim Eun S. , Emdee Jeffery L. , Cohn Richard K. 
Published: December 2010

Abstract
Over the course of the history of today's rockets, liquid rocket engines have been used as primary propulsion for most space launch vehicles and early ballistic missiles. The visions of historical figures such as Tsiolkovsky, Goddard, and Oberth have become reality, resulting in humans reaching the moon and space exploration programs that stretch beyond the earth's orbit. A liquid rocket engine uses fuel and oxidizer in liquid form. Various combinations of liquid propellants have been characterized, tested, and flown. Engines are also classified according to the engine power cycle, which determines how the propellants reach the combustion chamber. Liquid rocket engines utilize numerous design power cycles and propellants depending on the application and design requirements. This chapter provides an overview of liquid rocket propulsion. Key historic achievements associated with pioneering efforts and development of large operational liquid rocket engines are first discussed. The fundamentals of liquid rocket engines are then described along with underlying design theory and practical experience. Lastly, the classifications of liquid rocket engines are provided in terms of application, engine cycle, and propellant combination.
Liquid Propulsion: Thrust Chamber Design
Authors: Cohn Richard K. , Vega John C. , Kim Eun S. 
Published: December 2010

Abstract
The thrust chamber serves the critical purpose of converting the chemical energy stored in the propellants into the kinetic energy required to generate thrust. When the propellants enter the thrust chamber, they undergo a complex series of physiochemical processes such as atomization, vaporization, mixing, reaction, and expansion. A gas‐generator cycle or a staged‐combustion cycle uses an auxiliary combustion device to generate the power required to operate the pump in a much lower temperature environment. This chapter deals with key elements associated with thrust chamber design and is organized as follows. A comprehensive description of the thrust chamber is first given along with the underlying design concept and its applications. Typical nozzles used with the thrust chamber are then described. Finally, auxiliary combustion devices are summarized.
Nuclear Thermal Propulsion (
NTP
)
Authors: Borowski Stanley K. 
Published: December 2010

Abstract

The nuclear thermal rocket (NTR) derives its energy from fissioning uranium‐235 atoms contained within fuel elements that comprise the engine's reactor core. During operation, hydrogen (H
2
) propellant is pumped through coolant channels in the fuel elements where it is superheated to high temperatures and then expanded out a supersonic nozzle to generate high thrust at twice the specific impulse (
I
sp
∼900 s) of today's best chemical rockets. This technology is not new. Twenty rocket reactors were designed, built, and ground tested during the Rover and NERVA (Nuclear Engine for Rocket Vehicle Applications) programs conducted between 1955 and 1972. These programs demonstrated: (1) a wide range of thrust; (2) high‐temperature carbide‐based nuclear fuel; (3) sustained engine operation; (4) accumulated lifetime; and (5) restart capability. Ceramic metal fuels were also evaluated as a backup. The NTR has a significant growth capability. Configured as a “bimodal” system, the NTR can generate spacecraft electrical power. Adding an “afterburner” nozzle for oxygen (O
2
) injection and supersonic combustion in the engine's hot H
2
exhaust downstream of the nozzle throat can enable a variable thrust and
I
sp
capability. For future human missions to Mars, the NTR can reduce the required launch mass by ∼400 t compared to chemical propulsion. It also has fewer mission elements, simpler space operations, and the use of clustered, lower thrust engines can help reduce development cost and overall mission risk.