Squeeze-Film Damping of the Motion of a Control Flapper-Nozzle

A squeeze film used in a flapper-nozzle affords stand-alone properties to the flapper motion, meaning that it behaves in a dynamically stable manner. The device constitutes the first stage of a new family of two-stage electrohydraulic control valves. Successful mathematical modelling of it has been reported by Lin and Akers (1,2). Because of the expense of maintaining close manufacturing tolerances within the damper, the investigation included the extent of deterioration of dynamic response when the dimensions of the damper are varied, when the tolerances on the squeeze-film annular area are relaxed and when the annular clearance is increased. As a result of the investigation, the dimensions and other variables, chosen by trial-and-error procedures, appeared to be optimum from the point of view of dynamic performance, convenience of installation and cost.