定在音場と液滴燃焼との干渉 : 熱音響流の発生と燃焼促進(熱工学,内燃機関,動力など)

抄録

Combustion in standing sound wave induces a new type of convection that is named as thermo-acoustic streaming. The mechanism of the streaming is analyzed and experimental investigations are made to evaluate its influence on burning rate of a droplet. Since natural convection has characteristics very similar to the streaming, microgravity conditions were used to suppress it. Burning rates are measured for an accoustic frequency of 900 Hz and SPL of up to 150 dB under ambient pressure of 0.1 to 0.5 Mpa. As a result, the excess burning rate (k/k₀-1) is confirmed to be proportional to Gr_a^0.25 or Gr_a^0.5, where Gr_a is the ratio of acoustic radiation force to viscosity. The hypothesis that the streaming is driven by acoustic radiation force is validated and burning enhancement is explained through enhanced convective transfer due to the streaming.