*Article* **Experimental Study of Air Vessel Behavior for Energy Storage or System Protection in Water Hammer Events**

**Mohsen Besharat 1,2,\*, Maria Teresa Viseu 3 and Helena M. Ramos 2**


Academic Editor: Marco Franchini Received: 8 November 2016; Accepted: 14 January 2017; Published: 20 January 2017

**Abstract:** An experimental assessment of an air pocket (AP), confined in a compressed air vessel (CAV), has been investigated under several different water hammer (WH) events to better define the use of protection devices or compressed air energy storage (CAES) systems. This research focuses on the size of an AP within an air vessel and tries to describe how it affects important parameters of the system, i.e., the pressure in the pipe, stored pressure, flow velocity, displaced volume of water and water level in the CAV. Results present a specific range of air pockets based on a dimensionless parameter extractable for other real systems.

**Keywords:** water hammer; air vessel sizing; energy storage; dynamic behavior; CAES
