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Research Papers: Gas Turbines: Microturbines and Small Turbomachinery

Aerodynamic Design and Numerical Investigation on Overall Performance of a Microradial Turbine With Millimeter-Scale

[+] Author and Article Information
Lei Fu

Institute of Turbomachinery, School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, P.R.C.leizhenlin@gmail.com

Yan Shi, Qinghua Deng

Institute of Turbomachinery, School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, P.R.C.

Zhenping Feng

Institute of Turbomachinery, School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, P.R.C.zpfeng@mail.xjtu.edu.cn

J. Eng. Gas Turbines Power 132(3), 032301 (Dec 03, 2009) (9 pages) doi:10.1115/1.3159375 History: Received March 23, 2009; Revised March 28, 2009; Published December 03, 2009; Online December 03, 2009

For millimeter-scale microturbines, the principal challenge is to achieve a design scheme to meet the aerothermodynamics, geometry restriction, structural strength, and component functionality requirements while in consideration of the applicable materials, realizable manufacturing, and installation technology. This paper mainly presents numerical investigations on the aerothermodynamic design, geometrical design, and overall performance prediction of a millimeter-scale radial turbine with a rotor diameter of 10 mm. Four kinds of turbine rotor profiles were designed, and they were compared with one another in order to select the suitable profile for the microradial turbine. The leaving velocity loss in microgas turbines was found to be a large source of inefficiency. The approach of refining the geometric structure of rotor blades and the profile of diffuser were adopted to reduce the exit Mach number, thus improving the total-static efficiency. Different from general gas turbines, microgas turbines are operated in low Reynolds numbers (104105), which has significant effect on flow separation, heat transfer, and laminar to turbulent flow transition. Based on the selected rotor profile, several microgas turbine configurations with different tip clearances of 0.1 mm, 0.2 mm, and 0.3 mm, two different isothermal wall conditions, and two laminar-turbulent transition models were investigated to understand the particular influences of low Reynolds numbers. These influences on the overall performance of the microgas turbine were analyzed in detail. The results indicate that these configurations should be included and emphasized during the design process of the millimeter-scale microradial turbines.

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Copyright © 2010 by American Society of Mechanical Engineers
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Figures

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Figure 1

Meridional view and the profiles of the turbine stator and rotor

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Figure 2

Turbine power, efficiency, and specific power via stage expansion ratio for the four schemes

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Figure 3

Streamlines and relative velocity vectors in three kinds of diffusers

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Figure 4

Intermittency on pressure side of rotor blade by FINE/TURBO with different Reynolds numbers and various inlet eddy viscosity ratios of 10, 30, 60, and 100 (from left to right)

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Figure 5

Intermittency on pressure side of rotor blade by ANSYS CFX with different Reynolds numbers and various inlet eddy viscosity ratios of 10, 30, 60, and 100 (from left to right)

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Figure 6

Specific power and total-static efficiency of the seven cases

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Figure 7

Schematic diagram of final design for microgas turbines

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