BINGHAM PLASTIC ANALYSIS OF ER VALVE FLOW

Yield shear stresses and shear rates st a valve wall are derived from experimental results on a series of concentric cylinder valves. The fl uid constitutive equation used for this purpose is that of a Bingham P lastic. Valve plates (which are such that the radial gap is small comp ared to its mean pitch) are taken to be parallel so far as the derivat ion of the how upsilon's pressure upsilon's geometry model is concerne d. A range of electrode separations from 0.5 to 1.0 mm are used with h ow velocities being limited to the region where the viscous pressure d rop component is below that caused by the electro stress. Results show that (away from the region of low shear rates and high voltages) the wall stresses for equivalent conditions are comparable for different v alves, for a range of applied field strengths and mean flow velocities . Thus, provided the hysteretic region is avoided the fluid can be tre ated as a Bingham continuum with some stated reservations. However, th is is only applied with precision for the truly corresponding situatio ns defined in the paper.