Login | Signup now       

Guest

 Click to see how  

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

 
Document search results: "rayleigh"
 
 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          
 Rayleigh criteria and Combustion Instability  
 
Abstract    

A short literature review on Rayleigh's Criteria is provided. This criteria is widely used in mechanical and aerospace engineering areas to understand the phenomena of combustion instability. In continuously running combustion systems where combustion occurs inside a volume of relatively low losses, small amplitude pressure disturbance and small amplitude heat release fluctuations can couple with each other in a positive feedback loop leading to very large amplitude pressure oscillations often ending up in limit cycle oscillations. Such oscillations are detrimental to the combustion system (power or propulsion) for it exposes the system to large mechanical fatigue, thermal loads and can lead to catastrophic failures.

 
Go to document page
 
Added By - A Ghosh
Subject - Aeronautics and Astronautics
Document Type - Literature Review
 
   
   

 

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          
 The Role of Density Gradient in Liquid Rocket...  
 
Abstract    

Experimental and analytical studies were conducted to investigate key physical mechanisms responsible for flame-acoustic coupling during the onset of acoustically driven combustion instabilities in liquid rocket engines (LREs). Controlled experiments were conducted in which a turbulent hydrogen-oxygen (GH2-GO2) diffusion flame, established downstream of a two-dimensional model shear coaxial injector was acoustically forced by a compression driver unit mounted in a transverse direction and excited through a broad range of frequencies (200Hz-2000Hz) and amplitudes. Characteristic interactions between flame and acoustics visualized through OH* and CH* chemiluminescence imaging and dynamic pressure measurements obtained using high frequency dynamic pressure transducers indicated that small acoustic disturbances could be amplified by flame-acoustic coupling under certain conditions leading to substantial modulation in spatial heat release fluctuations. Density gradient between fuel and oxidizer was found to significantly affect the way acoustic waves interacted with density stratified flame fronts. The particular case of an asymmetric flame front oscillation under transverse acoustic forcing indicated that baroclinic vorticity, generat...

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

 

Title          
 Combustion Instability in Liquid Rocket Engin...  
 
Abstract    

Work on liquid rocket engine combustion instabilities began in the early 1940s (Culick and Yang 1995). One of the most critical concepts in liquid rocket combustion instability, that of time lag (as a coordinating factor in influencing organized oscillations in liquid rocket combustion chambers) originated around this time in von Kármán‟s group at the Jet Propulsion Laboratory around 1941 (cf. Summerfield 1951) shortly after oscillations were observed in early tests in liquid rocket engines in the United States. The essential idea was that there existed a finite time delay when an element of propellant entered the combustor and when heat was released from it. This delay controlled the phasing between heat release and pressure oscillations thereby making the system stable or unstable as per Rayleigh‟s criteria. In the years that followed, this model was applied to various studies involving combustion instability in liquid rocket engines. Gunder and Friant (1950), Yachter (1951) and Summerfield (1951) analyzed low frequency chugging instability arising from the interaction between feed system and combustion process using a constant time lag model. Crocco (1951;1952) introduced the time varying combustion time lag and use...

 
Go to document page
 
Added By - A Ghosh
Subject - Aeronautics and Astronautics
Document Type - Literature Review
 
   
   

Page 1 of 1