Long R, Lowe M, Cawley P
Department of Mechanical Engineering, Imperial College, London, SW7 2BX, UK.
Ultrasonics. 2003 Sep;41(7):509-19. doi: 10.1016/s0041-624x(03)00166-5.
The attenuation of the fundamental non-torsional modes that propagate down buried iron water pipes has been studied. The mode shapes, mode attenuation due to leakage into the surrounding medium and the scattering of the modes as they interact with pipe joints and fittings have been investigated. In the low frequency region the mode predicted to dominate over significant propagation distances approximates a plane wave in the water within the pipe. The established acoustic technique used to locate leaks in buried iron water pipes assumes that leak noise propagates as a single non-dispersive mode at a velocity related to the low frequency asymptote of this water borne mode. Experiments have been conducted on buried water mains at test sites in the UK to verify the attenuation and velocity dispersion predictions.
对沿埋地铁制水管向下传播的基本非扭转模式的衰减进行了研究。研究了模式形状、因泄漏到周围介质中导致的模式衰减以及模式与管接头和管件相互作用时的散射情况。在低频区域，预计在相当长传播距离内占主导地位的模式在管内水中近似为平面波。用于定位埋地铁制水管泄漏点的既定声学技术假定，泄漏噪声以与该水中传播模式的低频渐近线相关的速度作为单一非色散模式传播。已在英国测试地点的埋地水管上进行了实验，以验证衰减和速度色散预测。
