Supersonic Gas Dynamics and Combustion for Development of Ultra Micro Gas Turbine

摘要

A high spatial- and temporal-resolved laser Doppler anemometry (LDA) optics are designed and applied to the local velocity measurement inside a micro wave rotor cell. A micro wave rotor with a transparent cell (the inner section is 3 mm x 3 mm) was used. Water droplets were used as scattering particles for the LDA measurement. The pressure ratio and the rotor speed of the wave rotor were 2.5 and 5000 rpm, respectively. The total pressure inside the cell was also measured with a pressure transducer. The velocity history measured by the LDA has some scattering. It is considered that the data scattering is attributed to the droplet size distribution and the cycle variation of the flow. The propagation of the primary shock wave is detected by the LDA measurement. The traveling velocity is estimated to be 3.9 x 10~2 m/s, which is smaller than the theoretical value. The propagation of the secondary shock wave is also detected by the LDA measurement. The velocity history is consistent to the total pressure history. The maximum velocity at the same streamwise position is almost the same regardless of the transverse positions. The boundary layer thickness is estimated to be less than 0.5 mm at the maximum.