Tham khảo tài liệu 'bearing design in machinery episode 1 part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Here L is the width of the parallel plates in the direction normal to the flow in the z direction . Substituting the flow in Eq. 4-29 into Eq. 4-30 and integrating yields the expression for the pressure gradient as a function of flow rate Q dp - ì Q 4-31 This equation is useful for the hydrostatic bearing calculations in Chapter 10. The negative sign means that a negative pressure slope in the x direction is required for a flow in the same direction. FLUID FILM BETWEEN A CYLINDER AND A FLAT PLATE There are important applications of a full fluid film at the rolling contact of a cylinder and a flat plate and at the contact of two parallel cylinders. Examples are cylindrical rolling bearings cams and gears. A very thin fluid film that separates the surfaces is shown in Fig. 4-7. In this example the cylinder is stationary and the flat plate has a velocity U in the x direction. In Chapter 6 this problem is extended to include rolling motion of the cylinder over the plate. The problem of a cylinder and a flat plate is a special case of the general problem of contact between two parallel cylinders. By using the concept of equivalent radius see Chapter 12 the equations for a cylinder and a flat plate can be extended to that for two parallel cylinders. Fluid films at the contacts of rolling-element bearings and gear teeth are referred to as elastohydrodynamỉc EHD films. The complete analysis of a fluid film in actual rolling-element bearings and gear teeth is quite complex. Under load the high contact pressure results in a significant elastic deformation of the contact surfaces as well as a rise of viscosity with pressure see Chapter 12 . Fig. Fluid film between a cylinder and a flat-plate. Copyright 2003 by Marcel Dekker Inc. All Rights Reserved. However the following problem is for a light load where the solid surfaces are assumed to be rigid and the viscosity is constant. The following problem considers a plate and a cylinder with a minimum clearance hmin. In it
