The aim of this investigation was to develop a computer-aided design procedure for fluid couplings and torque converters. Three different classes of fluid transmission devices are considered i) The coupling in which input and output torques are equal throughout the working range, with efficiency rising from zero to a maximum at the minimum available slip condition; ii) The torque converter which is designed to give an increased torque with maximum efficiency at a turbine rotar speed which is less than that of the pump impeller; iii) The converter coupling in which the torque ratio varies from a maximum with the turbine runner stalled to approximately unity at coupling speed. The analyses are carried out by assuming that the fluid circulating within the closed circuit has a distributed velocity profile which increases linearly from zero at the mean radius, the radius about which the fluid circulates. That is the circulating motion is a forced vortex. The analyses have been developed by applying the fundamental one-dimensional flow relationships for continuity, moment of momentum and energy to a single streamtube and integrating over the limits of the device considered. This basic procedure is applied to all different types of hydrodynamic devices considered- Each device, e.g. baffled coupling, partially filled coupling, torque converter, etc., have their own specified problems which are considered and described separately. In all cases the losses occurring in the flow path have been considered to be composed of three components (i) incidence or shock loss, (ii) skin-friction loss and (iii) secondary flow circulation or bend loss. Empirical procedures are developed to describe these losses and their relative magnitudes compared. The theoretically predicted performance of each hydrodynamic device is compared with simpler theoretical procedures, available in the literature, and with experimental results available from industry. In general good agreement between theory and experiment is obtained. It is shown that the theoretical approaches developed here are an improvement on earlier ones where these were available, while in certain other cases, particularly those of the baffled and partially filled couplings, the approach may be claimed to be novel.
|Date of Award||1977|