Shock Waves (2006) 16:1–15 DOI 10.1007/s00193-006-0019-0 ORIGINAL ARTICLE Shock wave attenuation by grids and orifice plates A. Britan · O. Igra · G. Ben-Dor · H. Shapiro Received: 1 October 2003 / Accepted: 1 April 2004 / Published online: 22 August 2006 © Springer-Verlag 2006 Abstract The interaction of weak shock waves with porous barriers of different geometries and porosities is examined. Installing a barrier inside the shock tube test section will cause the development of the follow- ing wave pattern upon a head-on collision between the incident shock wave and the barrier: a reflected shock from the barrier and a transmitted shock propagating towards the shock tube end wall. Once the transmit- ted shock wave reaches the end wall it is reflected back towards the barrier. This is the beginning of multiple reflections between the barrier and the end wall. This full cycle of shock reflections/interactions resulting from the incident shock wave collision with the barrier can be studied in a single shock tube test. A one-dimensional (1D), inviscid flow model was proposed for simulating the flow resulting from the initial collision of the inci- dent shock wave with the barrier. Fairly good agreement is found between experimental findings and simulations based on a 1D flow model. Based on obtained numerical and experimental findings an optimal design procedure for shock wave attenuator is suggested. The suggested Communicated by O. Igra. A. Britan · O. Igra · G. Ben-Dor (B ) · H. Shapiro Department of Mechanical Engineering, Pearlstone Center for Aeronautical Engineering Studies, Protective Technologies R & D Center, Faculty of Engineering Sciences, Ben Gurion University of the Negev, Beer Sheva 84105, Israel e-mail: bendorg@bgu.ac.il A. Britan e-mail: britan@bgu.ac.il O. Igra e-mail: ozer@bgu.ac.il attenuator may ensure the safety of the shelter’s venti- lation systems. Keywords Shock wave attenuation · Shock interaction with porous obstacles PACS 47.40 · 43.20.El 1 Introduction Shock waves interaction with grid-like obstacles or orifice plates appears in many engineering applications. Such an interaction considerably modifies the flow field by introducing new shock waves, vorticities and regions of entropy and intense turbulence. As of today there is no systematic study of these phenomena although experimental works on this subject started appearing in the 1950s. Some examples of early works are: Dosanjh [1] investigated the wave pattern resulted from head- on collision of an incident shock wave with a grid-like obstacle. Specifically, using shadowgraph photography he checked the wave patterns developed far upstream and far downstream of the obstacle. He was the first to observe and explain the choking phenomenon witnessed in the supersonic flows immediately downstream of the grid-like obstacle. Franks [2] used a rotating drum cam- era schlieren system and a Mach Zehnder interferome- ter for recording the wave pattern and the instantaneous density distributions in the various regions resulting from the shock wave–grid interaction. Franks also ob- served the presence of a choking shock wave at the grid exit and offered analytical solution to this flow. His solution is based on the assumption that the flow undergoes an isentropic expansion filling the whole area