国产强奷伦奷片-久久婷婷五月综合色奶水99啪-软萌小仙自慰喷白浆-a国产一区二区免费入口 宅男噜噜噜66网站在线观看_4438╳全国最大色倩网址_欧美性大战久久久久久久_日韩免费视频

Product introduction

Fan muffler, and exhaust pipe muffler and drum induced draft fan muffler in the same form, adopts the resistance sound absorption and noise reduction principle for medium and high frequency broadband characteristics have a good effect, the resistance sound reduction principle for low and medium frequency and pulsation characteristics have a good effect, as well as micro-perforated muffler and impedance compound muffler. Resistance muffler is a production of absorption type muffler, according to the airflow channel structure is different, generally divided into straight pipe type, plate type, folding plate, honeycomb, acoustic flow, labyrinth type and elbow type. Resistive muffler is the use of sound waves in the propagation of porous sound absorbing materials, friction and viscous resistance, the sound energy into heat energy dissipation, so as to achieve the purpose of sound reduction.