2013 Fiscal Year Final Research Report

Examination of band gap effect in water hammer with fluid-structure interaction

Research Project

Project/Area Number	24760071
Research Category	Grant-in-Aid for Young Scientists (B)
Allocation Type	Multi-year Fund
Research Field	Materials/Mechanics of materials
Research Institution	Tokyo Institute of Technology
Principal Investigator	INABA Kazuaki 東京工業大学, 理工学研究科, 准教授 (00408725)
Project Period (FY)	2012-04-01 – 2014-03-31
Keywords	流体―構造連成 / 連続体力学
Research Abstract	A water hammer occurs by a sudden closing of a valve or an accidental stopping of a pump. The difference in Young's modulus and dimensions of the tube results in the change of the propagation speed of the water hammer. Recently, a periodic structure of a rod with periodic weights is known to cut wave components as known to be the band gap effect. In the present study, we examined whether the tube with periodic weights can decrease impact tube responses in water hammers. Water hammer experiments were conducted with a polycarbonate tube and steel clamps. The periodic structure with more than 5 clamps attenuated the peak of water hammers about 20% in experiments. High frequency components (3-5 kHz) were attenuated with the repeated structure in the Wavelet analysis. Numerical simulations revealed that the interval of clamps similar to the frontal averaged wavelength indicated similar attenuation as the experimental results.