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UID:0-265@aerospace.technion.ac.il

DTSTART;TZID=Asia/Jerusalem:20210412T163000

DTEND;TZID=Asia/Jerusalem:20210412T173000

DTSTAMP:20230525T063758Z

URL:https://aerospace.technion.ac.il/events/combustion-dynamics-of-an-acou
 stically-excited-scramjet-engine/

SUMMARY:Combustion Dynamics of an Acoustically  Excited Scramjet Engine
DESCRIPTION:Lecturer:Neta Yokev\n Faculty:Department of Aerospace Engineeri
 ng\n Institute:Technion – Israel Institute of Technology\n Location:http
 s://technion.zoom.us/j/95894901855\n Zoom: \n Abstract: \n Details: \n The
  supersonic combustion ramjet\, or scramjet\, is an air-breathing engine d
 esigned for cruise at Mach number of 5 and above. The high-speed flow with
 in the combustor poses a major issue with regard to combustion\, because t
 he air and fuel must mix and ignite within a time frame of typically less 
 than 1 millisecond. This makes flame anchoring and efficient combustion ve
 ry difficult. Moreover\, due to the elevated air stagnation temperatures a
 t flight of high Mach number\, thermal management becomes a big challenge.
  This study addresses these three topics using a new experimental setup.\n
             It was found that it is possible to alter the flame
  stabilization mode by distributing the fuel between two fuel injectors\, 
 one in the cavity and one upstream of the cavity. When a sufficiently high
  fuel flow rate in the cavity led to flame stabilization in the fuel jet
 ’s wake\, and a more confined combustion zone. Shadowgraph imaging showe
 d that injection of the fuel from the cavity floor at a sufficient momentu
 m penetrated the shear layer over the cavity and enabled flame propagation
  upstream of the cavity. It was concluded that the heat release distributi
 on and pressure profile in the combustor could be significantly influenced
  by the fuel injection distribution through its impact on the flame stabil
 ization mode.\nIn addition to hydrocarbon gaseous fuel (ethylene)\, simula
 ted synthetic gas (mixture of hydrogen and methane) was used. Syngas is a 
 product of an endothermic chemical reaction between water and hydrocarbon 
 fuel\, called steam reforming\, enabling up to 3 times higher heat sink th
 an fuel cracking. It was found that the simulated syngas did not burn on i
 ts own in the supersonic chamber due to the relatively long ignition delay
  of the methane-hydrogen mixture compared to ethylene.\nForced acoustic ex
 citation was investigated as a method for mixing enhancement in scramjet e
 ngines for the first time.  It was found that acoustic forcing at frequen
 cies of below ~100 Hz during transition between 2 combustion modes led to 
 a higher probability of the more efficient combustion mode. This led to an
  average pressure-rise of 14% compared the non-excited baseline. Analysis 
 of the chemiluminescence and pressure data suggested that the acoustic for
 cing excited heat release oscillations at ~10 Hz at the cavity shear layer
 \, which were enhanced further downstream leading to a more efficient comb
 ustion.\nZoom meeting
CATEGORIES:Seminars
LOCATION:https://technion.zoom.us/j/95894901855

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