Login | Signup now       

Guest

 Click to see how  

HOME | VIDEOS | DOCUMENTS | COLLECTIONS | UPLOAD | BROADCAST | MY ACCOUNT | FEEDBACK | ABOUT

 
Document search results: "flow"
 
 Documents
 
   Featured
   Most Viewed
   Most Recent
   Most Discussed
 
 All Subjects
 
  Aeronautics and A...   
  Anthropology   
  Architecture   
  Arts   
  Astronomy   
  Bioengineering   
  Biology   
  Business and Mana...   
  Chemistry and Che...   
  Civil and Environ...   
  Cognitive Science   
  Communications   
  Computer Science   
  Earth and Atmosph...   
  Economics   
  Education   
  Electrical Engine...   
  Energy   
  Entrepreneurship ...   
  History   
  Humanities   
  Journalism   
  Laboratory Equipm...   
  Languages and Lit...   
  Linguistics   
  Material Science ...   
  Mathematics   
  Mechanical Engine...   
  Media Arts   
  Medical Sciences   
  Music   
  Nanoscience and N...   
  Neuroscience   
  Nuclear Engineeri...   
  Oceanography and ...   
  Philosophy   
  Physics   
  Political Science   
  Psychology   
  Public Health   
  Robotics and Arti...   
  Softwares and Pro...   
  Uncategorized   
 

 

 

 

 

 

 

Title          
   
 
Abstract    

Creeping flow (flow with Re << 1) past a sphere is described by Stokes’* celebrated solution (1851). The solution is formulated with the help of the streamfunction which ensures mass conservation on a differential level. However, if the streamlines and velocity contours for this flow are plotted, the image suggests that global continuity is violated. This can often lead to some confusion and doubt over the validity of the solution, so a simple demonstration follows to show that Stokes’ solution also satisfies global mass conservation, despite the illusion presented by the streamlines and velocity contours.

 
Go to document page
 
Added By - daanish
Subject - Mechanical Engineering
Document Type - Question and Answer
 
   
   

 

Title          
 Laminar Separation Bubble  
 
Abstract    

This essay focuses on the phenomenon of Laminar Separation Bubble observed at Low Reynolds Numbers. The effect of this bubble on the airfoil characteristics is discussed. Airfoils used at low Reynolds numbers have to be designed taking into consideration the finite space and time occupied by the bubble. Active as well as passive mechanisms to control/delay the formation of the bubble are also mentioned.

For conventional aircraft wings, whose Reynolds number exceeds a million, the flow is typically turbulent with the boundary layer able to strengthen itself by ‘mixing’. Consequently flow doesn’t separate until high angles of attack are encountered. For lower Reynolds numbers, the flow is initially laminar and is prone to separate even under mild adverse pressure gradient. Under certain flow conditions, the separated flow reattaches and forms a Laminar Separation Bubble (Fig. 1) while transitioning from laminar to turbulent state. Laminar separation bubble could modify the effective shape of the airfoil and consequently influence the aerodynamic performance, generally in a negative manner.

The need to understand low Reynolds number (104 to 106) aerodynamics is driven by variety of applicat...

 
Go to document page
 
Added By - anandsaxena
Subject - Aeronautics and Astronautics
Document Type - White Paper
 
   
   

 

Title          
 Physics of flow about lifting bodies  
 
Abstract    

Physics of lifting bodies is studied in some depth using the NASA Foilsim software freely available on website.With this software we can investigate how an aircraft wing produces lift by changing the values of different factors that affect lift.There are several different versions of FoilSim II which require different levels of experience with the package, knowledge of aerodynamics, and computer technology. An offline version can be downloaded and being interactive a variety of problems can be analyzed using it. In the present work a detailed analysis of ‘Physics of flow about lifting bodies' is studied.

FoilSim is a computer simulator program that calculates the total "lift" of a specified wing. By using this program, the user can prove that the lifting capacity of the wing can remain the same at different airspeeds-as long as the angle of attack is changed to compensate. If the airspeed remains unchanged, an increase in the angle of attack will initially increase the lifting capacity of the wing. 

 
Go to document page
 
Added By - anandsaxena
Subject - Aeronautics and Astronautics
Document Type - White Paper
 
   
   

 

Title          
 Physical Realization of Chaotic Behavior: A R...  
 
Abstract    

The chaotic behavior of uniformly hyperbolic systems is well known. Geodesic flows with negative Gaussian curvature are among the well characterized examples of such systems, as it is proved that a geodesic flow on a compact factor of the hyperbolic plane is an Anosov flow. However, surfaces with constant negative Gaussian curvature cannot be realized as an embedded surfaces in R^3 and hence were thought to be physically unrealizable until recently. On the other hand, it is known that every compact orientable surface of negative Euler characteristics, i.e. with genus more than one, supports a Riemannian metric of constant negative Gaussian curvature and it has been recently proved that for any compact orientable closed surface of genus greater or equal to zero, there exists a mechanical linkage, such that its configuration space is homeomorphic to the surface. To this end, another recent study identified a detailed numerical example of a triple mechanical linkage with a uniformly chaotic attractor. In this paper, this topic of physical realization of uniformly chaotic behavior is studied, understood and reviewed with necessary background materials.

 
Go to document page
 
Added By - soumikpsu
Subject - Mathematics
Document Type - MS Thesis
 
   
   

 

Title          
 Experimental Study of Compressible Pipe Flow ...  
 
Abstract    

Anna Ekblom Johan Gullman-Strand's (KTH Sweeden) work on compressible pipe flow with friction and heat addition. The aim of the presented work was to compare existing theoretical analysis with experimental results in the feld of compressible pipe ow in a straight circular pipe with constant cross section area subjected to wall friction and heat addition. The equations describing pipe ow subjected to friction have been rederived. Two different models have been compared. The experiments were conducted on four pipes differing in length and friction factor.Quantities such as total inlet pressure, total inlet temperature, static pressure distribution along the pipe, venturi nozzle pressure difference, power added, outlet dynamic pressure distribution and outlet total temperature have been measured in order to determine the dependence on heat addition and friction. There was no apparent effect of heating on the flow eld though the input power was entirely transfered to the ow. The inuence of friction seems to have the predicted effect, since the achieved outlet Mach numbers were similar for all four pipes for similar input conditions. Inn contrast to the theoretical model of one-dimensional ow, the outlet Ma...

 
Go to document page
 
Added By - autocrawler
Subject - Mechanical Engineering
Document Type - MS Thesis
 
   
   

 

Title          
 Modeling and Simulation of Mixing Layer Flows...  
 
Abstract    

Film cooling has been selected for the thermal protection of the composite nozzle extension of the J-2X engine which is currently being developed for the second stage of NASA’s next generation launch vehicle, the Ares I rocket. However,several challenges remain in order to achieve effective film cooling of the nozzle extension and to ensure its safe operation. The extreme complexity of the flow (three-dimensionalwakes, lateral flows, vorticity, and flow separation) makes predicting film cooling performance difficult. There is also a dearth of useful supersonic film cooling data available for engineers to use in engine design and a lack of maturity of CFD tools to quantitatively match supersonic film cooling data. This dissertation advances the state of the art in film cooling by presenting semi-empirical analytical models which improve the basic physical understanding and prediction of the effects of pressure gradients, compressibility and density gradients on film cooling effectiveness. These models are shown to correlate most experimental data well and to resolve several conflicts in the open literature. The core-to-coolant stream velocity ratio, R, and the Kays acceleration parameter, KP, are identified as the critical paramete...

 
Go to document page
 
Added By - kdellimo
Subject - Aeronautics and Astronautics
Document Type - PhD Thesis
 
   
   

 

Title          
 Hints for understanding low speed wind tunnel...  
 
Abstract    

The effort here has been to compile and present collectively the concepts of Low Speed Wind Tunnel. I have tried to make it explanatory with help of large number of figures and pictures whose sources have been mentioned under them. I have tried to incorporate as much latest information as available via Internet although the backbone of the work is ‘Wind Tunnel Technique’ by R.C. Pankhurst, National Physical Laboratory, Teddington, England. It includes a very descriptive documentation of the Wind Tunnel and in a very organized manner.This work was done as an assignment for one of the undergrad courses. Information may not be very current but the general principles remain the same nevertheless.

Wind tunnel testing is the technical support of any major development process involving aerodynamics. It is used for aircraft, helicopters,cars, trains, and laboratory research.It is estimated that it took the Wright Brothers less than 20 hours of wind tunnel testing to produce their successful Flyer (although their empirical research was a life time achievement). The Douglas DC-3, perhaps the most successful commercial aircraft ever built, required about 100 hours of wind tunnel testing. Wind tunnel time has been steadi...

 
Go to document page
 
Added By - anandsaxena
Subject - Aeronautics and Astronautics
Document Type - White Paper
 
   
   

 

Title          
 Supersonic Nozzle design by Method of Charact...  
 
Abstract    

Using the 2D Method of Characteristics (MOC), the contour of a two dimensional minimum-length nozzle for the expansion of air to a design exit Mach number of 2 is computed and graphed. The problem is extended to include a nozzle with a finite expansion section which is a circular arc with a diameter equal to three throat heights. C++ source codes for the 2 nozzles are included. By inputting the values of gas constant, test section mach number, throat height and level of precision one can design nozzles for different working fluids at different test section mach numbers.

The report was generated as a part of a graduate course on compressible aerodynamics taught that semester by Dr John D Anderson. His book entitled 'Modern Compressible Flow - with Historical perspectives' contain a good chapter on the use of the MOC in designing supersonic nozzle contours (Chapter 11 of the third edition).

 
Go to document page
 
Added By - A Ghosh
Subject - Aeronautics and Astronautics
Document Type - White Paper
 
   
   

 

Title          
 Fiber-Optic based Dynamic Pressure sensor for...  
 
Abstract    

Acquiring accurate, transient measurements in harsh environments has always pushed the limits of available measurement technology. Until recently, the technology to directly measure certain properties in extremely high temperature environments has not existed. Advancements in optical measurement technology have led to the development of measurement techniques for pressure, temperature, acceleration, skin friction, etc. using extrinsic Fabry-Perot interferometry (EFPI). The basic operating principle behind EFPI enables the development of sensors that can operate in the harsh conditions associated with turbine engines, high-speed combustors, and other aerospace propulsion applications where the flow environment is dominated by high frequency pressure and temperature variations caused by combustion instabilities, blade-row interactions, and unsteady aerodynamic phenomena. Using micromachining technology, these sensors are quite small and therefore ideal for applications where restricted space or minimal measurement interference is a consideration. In order to help demonstrate the general functionality of this measurement technology, sensors and signal processing electronics currently under development by Luna Innovations were used to...

 
Go to document page
 
Added By - ajayvs
Subject - Mechanical Engineering
Document Type - Term Paper
 
   
   

 

Title          
 A Technical Essay on the Gyroplane  
 
Abstract    

A study of “Gyroplane” and its historical evolution, general characteristics, flight characteristics, various designs, potential applications and aerodynamics explaining its flight is attempted. “Gyroplane” is an official term designated by the Federal Aviation Administration (FAA) describing an aircraft that gets lift from a freely turning rotary wing, or rotor blades, and which derives its thrust from an engine-driven propeller. The focus is on highlighting the differences between a Gyroplane and a conventional helicopter, relative merits and demerits and to trace the development to helicopters from autogiros. What lies ahead in the future for gyroplanes is also discussed.

Cierva thought of designing a flying machine that remains stable, safe and controllable irrespective of its forward speed. He segregated the function of lift and forward propulsion, where the former was done by a freely rotating rotor (and not wings) and latter by a conventional pusher or tractor engine.The rotor of an Autogiro (term coined and patented by Cierva) always works in a state of autorotation and a small upward flow is sufficient to rotate the disk. Thus, as long as the machine has forward motion the rotor would produce sufficient lif...

 
Go to document page
 
Added By - anandsaxena
Subject - Aeronautics and Astronautics
Document Type - White Paper
 
   
   

Page 1 of 2
     Next >>