管群を内蔵するダクトにおける気柱共鳴現象の発生特性

抄録

In the present paper the attention is focused on the characteristics of acoustic resonance in in-line tube banks inside the duct. We have examined the characteristics of acoustic resonance generated from in-line tube banks with tube pitch ratio of 2.8 in the flow direction. The both sides of tube banks was covered by the sound transmission wall which were connected with two cavities. These cavities have an effect of controlling the acoustic field and resonant frequency. The single high peak was formed at the spectrum of sound pressure level at gap velocity of 10 ~ 40m/s. As the gap velocity increased, the peak frequency increased. Strouhal number became about 0.15. At the gap velocity of 25 m/s, the acoustic resonance of first mode in the transverse direction occurred. As the gap velocity increased, the acoustic resonance of first mode in the longitudinal direction occurred at 32m/s. The Strouhal number agreed well with previous experimental results.