Magneto-hydrodynamically lubricated externally pressurised bearing with variable film thickness

Summary This paper studies theoretically the use of a conducting lubricant in an externally pressurised bearing with variable film-thickness in the presence of an axial magnetic field. The flow and other characteristics are determined and it is shown that the pressure and load capacity can be increased by increasing the strength of the applied magnetic field at a given flow rate. But at a given feeding pressure the load capacity and pressure do not depend upon the magnetic field. The load capacity of this bearing is greater than that of a bearing having a constant film-thickness. It is also pointed out that the frictional drag on the rotor can be minimised by supplying electrical energy to the system.Nomenclature angle which the rotor surface makes with the stator (see fig. 1) - angular velocity of the rotor - _t terminal voltage between the electrodes - _t.o.c. open circuit voltage - viscosity of the lubricant - conductivity of the lubricant - B ₀ strength of the applied magnetic field - E _r radial component of the electric field - h variable film-thickness - h ₀ minimum film-thickness - I total current - I _s.c. short circuit current - L depth of the recess - M Hartmann number - p pressure - p _e exit pressure - p _i inlet pressure - Q rate of volume flow - r radial coordinate - R ₀ radius of the recess - R outer radius of the stator - R _i internal resistance - T frictional drag - u radial velocity - v tangential velocity - W load capacity - normalised load capacity - z axial coordinate