TY - JOUR
TI - Unsteady flow and load in 50% partial admission control stage with different admitting arc distributions
AU - Gao Ke-Ke
AU - Wang Shun-Sen
AU - Shi Dong-Bo
JN - Thermal Science
PY - 2016
VL - 20
IS - 13
SP - 805
EP - 813
PT - Article
AB - Full three-dimensional unsteady numerical investigation on an axial air  turbine in 50% partial admission is conducted. The partial admission turbines  are under different unsteady loading and unloading process, as well as flow  parameters, respectively. The loss coefficient and static pressure  distributions at the key position are presented in detail to analyze the  nonuniformity originated from partial admission. The results show that the  nonuniformity decreases along flow direction and the efficiency of control  stage also decreases but with the uniformity improved downstream of the  rotors with increasing admitting numbers in equal partial admission degree.  The reasons for efficiency decreasing are reasonably explained with windage  and sector end losses presented by static entropy distributions. The periodic  changes of unsteady forces in amplitude and direction are also compared and  transformed in the frequency domain by FFT method. The largest  circumferential exciting force factor which is remarkably larger than the  corresponding axial exciting force factor decreases by 13.2% with the  increase of admitting arc number. Compared with the common distribution of  two symmetric admitting arcs, the maximum exciting force factor of triangle  admitting arc distribution drops 11.3% with the mere efficiency decrease of  1.32%. The multiple admitting arc turbines are more conducive to be applied  to submarines which concerns more about exciting force other than efficiency.  Efficiency and unsteady forces are both worth being taken into consideration  in the practical applications.