Department of Aeronautic Engineering

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Browsing Department of Aeronautic Engineering by Author "I. O. Otaiku"

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    Unsteady performance of degraded compressor and turbine blades of an aero-engine at varying ambient and turbine inlet temperatures
    (FETiCON, 2023-08-04) I. O. Otaiku; I. O. Otaiku
    The paper presents the modelling of unsteady performance of a degraded 4-stage compressor and single stage gas generator turbine blades of PT6T turboshaft aero-engine of a helicopter. The two sections were set as control volumes for analytical and numerical modeling. Numerically, The blade specimens (NACA 65 series) were developed using SOLIDWORKS 20 and simulations performed with FLUENT in ANSYS 20.0. The RANS (Reynolds-averaged Navier–Stokes) equations with Shear Stress Transport model SST (k-w) were chosen for the unsteadiness of pressure and temperature distributions over different levels of reductions in surface area of the blades’ pressure side. 900 x 103 mesh elements size were selected and the boundary conditions-inlets for the two control volumes were 295-325 K and 1083 – 1245 K for compressor and turbine respectively. Analytically, equations for different levels of degradations (surface area reductions) were developed to determine their flow performance at new pressure and temperature for compressor (∆P_2C,∆T_2C) and turbine (∆P_3T,∆T_3T) with change in time and the corresponding rise in centrifugal stress. Results from FLUENT predicts the performance of the sections for 10% surface area reduction with complex structure in the turbulent flow imposes high fatigue stress, hence shows the highest closeness to surge margin. For the compressor, the result emphasizes the impact of inlet conditions on degraded blades over exit conditions. Also in the turbine, velocity contour shows adverse/backward flow as a result of high turbulence formation and rising fatigue due to change in exit pressure flow from stage to stage in the compressor. This exit pressure determines the TIT in the turbine which is a function of efficiency of the single stage gas generator turbine and is crucial to the overall efficiency of the engine and the safety of the engine as a whole. In conclusion, the inter-component flow behaviour between the degraded compressor and turbine as revealed in this study shows the near real-life situation of the engine performance. Summarily, the accurate engine life estimation can be deduced from TIT rising from 1100-1200 K and centrifugal stress 60MN/mm2.