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The CFD Analysis of Subsonic Flow Around Struts of Airfoil and Cylindrical Shape Attached to a Conical Diffuser at Exhaust of a Gas Turbine Engine

2019; Transstellar Journal Publications and Research Consultancy Private Limited (TJPRC); Volume: 9; Issue: 4 Linguagem: Inglês

10.24247/ijmperdaug201996

2249-6890

Vinod. L et al. Vinod. L et al.,

Computational Fluid Dynamics and Aerodynamics

After burners are employed in an aero engine of a fighter aircrafts, to achieve maximum thrust during takeoff, climb and during some special combat maneuvers. Since the fuel consumption is high during the afterburning operation it is employed only when necessary. The diffuser duct is the first component of the afterburner system, situatedimmediately next to the exit of the low-pressure turbine.The struts are the supporting structures, which connect the parts of diffuser duct.These struts will guide the flow in the diffuser duct.The presence of the struts will cause some pressure losses.The flow is decelerated in the diffuser duct.The Mach number also reduces along the length of the diffuser. The design of the diffuser duct should be made so that the recirculation should be minimum at the exit of the diffuser and the thermodynamics properties at the exit should meet the requirement for the proper mixing of the fuel and air with the hot gases passing through the diffuser & hence ensures complete combustion in the upstream zones of the diffuser. The flow inside an afterburner is highly complex due to the presence of the diffuser, flame stabilizer, variable area nozzle and the interaction between core and bypass flow through anti-screech holes. Therefore the performance of afterburner depends to a great extent on the internal aerodynamics. Experimental analysis of such flow is a difficult task. Cost and time involved for optimization design are very high. Computational fluid dynamics (CFD) provides a cost effective solution in analyzing. Its suitability to support the combustion process for the design of short efficient reheats system. Hence in this study, the flow in the diffuser duct in details by carrying out the analysis of subsonic flows in a three-dimensional model of an afterburner duct using CFD. The flow in the bypass region of the duct is considered, as it does not have any impact on diffuser performance. In the current study two stages viz. diffuser duct with struts and withoutstruts were carried out and for both cases the pressure recovery, total pressure loss, essential flow properties like Mach number, velocity, statics pressure, swirl are compared for both the cases.Considering the periodicity of geometry, analysis has been carried out using 45degree sector model of the diffuser duct with and without struts.Using ICEM-CFD pre-processor an unstructured grid has been generated and Navier-stroke equation is applied to carry out using ANSYS CFX CFD software, flow simulated by solving governing equation of mass, momentum, energy.Turbulence closure is achieved with k-epsilon turbulence model with standard wall functions.