PSI - Issue 47

Bayu Anggara et al. / Procedia Structural Integrity 47 (2023) 675–684 Bayu Anggara, Dominicus Danardono DPT*, Eko Prasetya Budiana / Structural Integrity Procedia 00 (2019) 000 – 000 6

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The operating condition in this simulation is STP (Standard Temperature and Pressure) at 1 atm or 101325 Pascal. The Reynolds number used is 2 x 10 6 . This Reynolds number refers to the boundary layer of the airfoil if the inlet velocity is 8 m/s. The pressure-velocity coupling scheme in this study is Semi-Implicit Method for Pressure-Linked Equations (SIMPLE). The turbulent study in this simulation used a Realizable k- ε viscous model. T he second-order spatial and temporal discretization schemes are employed to solve pressure, turbulent kinetic energy, and dissipation rate. The physical setup time is T/360, where T is the rotation period of the rotor. The maximum iteration number each time step is 250, and the residuals are set as 10 -3 . 2.4. Model Validation In this study, validation was carried out by comparing the power coefficient (Cp), which was taken as model validation in this simulation. The average Cm data for each TSR variation is from 0.5 to 2.5 comparison can be seen in Fig 5. Cp was obtained from the average Cm multiplied by TSR. The coefficient of power results in this study compared with the reference Cp calculated from the investigations of Song et al. (2019). and the experimental Cp from Raciti Castelli et al. (2011). Maximum errors or deviations in this study and previous studies reached 5.04%, with an average disparity of 1.05%, which can be said to be a good validation.

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Fig. 5. Validation with present study

3. Result and Discussion 3.1. Moment Coefficient

The value of Cm in one rotation of the rotor varies depending on the angle of attack experienced by the rotor. The radar diagram in figure 6 shows a constant change in the value of Cm during one rotor rotation. In the variation of the addition of HEV, the value of Cm looks greater when compared to the variation without HEV under TSR 1.5 conditions. Figure 6 shows the curve of Cm repeating every 120° degree, which occurs because the turbine has three blades. For blades with variations in the addition of HEV, it can be seen that the value of Cm shown is greater than the turbine without variation or clean airfoil. The maximum instantaneous torque coefficient is located near the angles θ = 70°, 190°, and 310°. Meanwhile, the instantaneous minimum torque coefficient is situated near the θ = 0°, 130°, and 250°. In general, HEV can improve the characteristics of the torque generated by the turbine.