Design of a fluid rotaryjoint prototype

Sammanfattning: This thesis, which has been carried out at the department of research and development at Cobham Antenna Systems, comprises the development of a fluid rotary joint (FRJ) prototype and shall provide a thorough insight in relevant design aspects. Based on input parameters and objectives derived from an actual Cobham project, the possibility of manufacturing a fluid rotary joint in-house has been investigated. A rotary joint is sub-system built up by modules linking signal transmission between the stationary and rotating parts of a microwave communication system, typically a rotating radar antenna. High power may generate a need of liquid cooling, i.e. a need of a fluid rotary joint module enabling connection of the up- and downstream of a recirculating cooling system, independent of antenna rotation and with minimal leakage. The typical FRJ features a bearing supported rotor mounted with a number of rotary seals inside a casing, referred to as stator, with channels guiding fluid from one to the other. Key objectives of the design are the flow channel configuration and flow performance relative geometrical size and structural integrity. As a result of the comprehensive pre-study three FRJ concepts were created and evaluated based on a customer requirement specification. The most advantageous design, in terms of e.g. manufacturability and flow performance potential, a multi-channel rotor design with mechanical face seals, was selected for further development. The CAD models were created in Solid Edge ST5, evaluated using FEM-analysis in ANSYS Workbench 14.5 and CFD analysis in ANSYS Fluent. The resulting prototype design features wide internal channels, a generous centre bore clearance equivalent to a diameter of 58 mm, robust mechanical face seals and a sturdy stainless steel stator and rotor design with a total weight below 29.2 kg. With a total pressure loss per channel of less than 0.0065 MPa at the specified mass flow rate of 1.5 kg/s the module are capable of mass flow rates up to 2.5 kg/s until reaching the specified maximum pressure loss of 0.02 MPa. Keywords: Rotary union, Rotary coupling, Flow loss, FRJ, RJ