Influence of inlet and outlet shift on the performance of a micro pneumatic turbine

This article proposes micro pneumatic turbines with shift inlet and outlet. The rotation speeds and output powers of the micro pneumatic turbines with four inlet and outlet layouts [radial inlet and radial outlet (RIRO); inlet and outlet both circumferential shift (IOBS); radial inlet and axial outlet (RIAO); inlet circumferential shift and axial outlet (ISAO)] are calculated by using actual conditions driving simulation. Moreover, the influence of inlet and outlet layout on turbine performance is analyzed according to flow characteristics and the Ω-vortex identification criterion. Furthermore, the maximum rotation speed and corresponding structure parameters and output power of the micro pneumatic turbine with the optimal inlet and outlet layout are obtained by using quadratic regression equations. Finally, the effects of inlet and outlet angles on the performance of the turbine with the optimal inlet and outlet layout are studied. The results indicate that the turbine with an IOBS layout can effectively alleviate abrupt pressure changes near the blade, reducing the occurrence of vortices and flow separation, and exhibiting the best performance. The maximum rotation speed of the IOBS turbine reaches to 356.43 krpm, and the corresponding output power is 253.68 W when the turbine diameter, blade height and tip clearance are 12.5, 2.6, and 1 mm, respectively. The influence of inlet angle on IOBS turbine performance is significant, whereas that of outlet angle is small.