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ISSN Online: 2688-7231

ISBN Online: 978-1-56700-478-6

Proceedings of the 24th National and 2nd International ISHMT-ASTFE Heat and Mass Transfer Conference (IHMTC-2017)
December, 27-30, 2017, BITS Pilani, Hyderabad, India

ANALYSIS OF FLOW IN AFTERBURNER

Get access (open in a dialog) DOI: 10.1615/IHMTC-2017.1430
pages 1025-1032

Аннотация

Afterburners are presently used in military jet aircrafts. The main disadvantages faced in the jet aircrafts, with afterburner, are the instabilities like Buzz and Screech. The high frequency instabilities called Screech in the jet aircraft will slacken the nuts and bolts and is even detrimental to the life of the aircraft. Hence, it is necessary to mitigate these instabilities in the afterburner for its efficient and effective operation. An attempt is made in this work for the computational analysis of flow in the afterburner which is followed by acoustic analysis to study the absorption of acoustic energy in the screech liner. A 1/3rd model of the afterburner consisting of diffuser with struts, flame holder or V-gutter, liner with screech holes and cooling holes and casing are created in Solidworks and the full 360° model is imported into Ansys (Fluent) for computational analysis of the fluid flow. k-ε turbulence model with SIMPLE algorithm is used for the analysis where energy equation is used for temperature calculations. Kerosene (C12H23) is taken as the fuel and virtual fuel injectors are specified for fuel injection. Species transport and discrete phase model is selected for combustion. The contours showing the variation of temperature, pressure, density and Mach number along the length of afterburner are plotted. It is observed that the velocity of the fluid decreased from 0.5 to 0.3 Mach in the diffuser section. A recirculation zone is observed behind the V-Gutter. The maximum temperature of 2400 K is observed in the afterburner. Desired Mach number of 1.1 could be obtained at the exit of the nozzle. This CFD model and the computational results are imported into ACTRAN software where the acoustic transmission loss for the various frequencies is obtained. The transmission loss is obtained for the two cases, first afterburner with liner and second afterburner without liner. It is observed that the afterburner with screech liner has the maximum transmission loss at the frequencies where there is high acoustic pressure and at the remaining frequencies the acoustic pressures are mitigated due to the use of liner. Hence the acoustic instabilities could be effectively mitigated with the introduction of screech liner in the afterburner.