Inlet Swirl and Dump Gap Effect on Static Pressure Recovery in Dump Diffuser-Combustor using Two Equation Turbulence Model
Ajay Kumar Sahu1, Prakash Ghos2

1Ajay Kumar Sahu, School of Mechanical Engineering, KIIT University, Bhubaneswar, India.
3Dr. Prakash Ghose*, School of Mechanical Engineering, KIIT University, Bhubaneswar, India.
Manuscript received on February 10, 2020. | Revised Manuscript received on February 24, 2020. | Manuscript published on March 10, 2020. | PP: 1214-1223 | Volume-9 Issue-5, March 2020. | Retrieval Number: E2758039520 /2020©BEIESP | DOI: 10.35940/ijitee.E2758.039520
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Abstract: Cold flow through an axi-symmetric dump diffuser, provided with a swirl effect at inlet is studied by using various two equation k-ε turbulent models such as; standard k-ε, RNG k- ε and Realizable k-ε model. There is a liner with a liner dome head of hemispherical in shape is used as a bluff body. From the comparison in between the three k-e turbulent models, it has been observed that the overall prediction of flow variables with Realizable k-e model are much better than others. The effects of dump gap and inlet swirl on velocity distribution and pressure variation on liner and casing walls have been investigated. The static pressure recovery within the diffuser is evaluated from area weighted average pressure at inlet and exit plane. It is noticed that an optimum inlet swirl results in the most effective pressure recovery due to the minimum irrecoverable energy dissipation in the vortices formed in the domain. The optimum swirl number is found to be 0.38 and it occurs when DG (non-dimensional dump gap) is kept as 1.0. The variation in dump gap changes the flow pattern and the possible pressure recovery. As the dump gap is increased, the static pressure is recovered more effectively with moderate swirl level in the inlet flow. 
Keywords: Dump Diffuser-Combustor, Swirl, Dump Gap, Static Pressure Recovery.
Scope of the Article: Probabilistic Models and Methods