HIGH-SPEED SEAL FLOWS WITH TEMPERATURE SENSITIVE VISCOSITY

Couette flow with temperature-thinning fluids is treated, by an approximation where the fluidity is allowed to vary linearly from the magnitude at maximum temperature. The slope of this function is matched to the slope of the fluidity-temperature curve for the real fluid, evaluated at the maximum temperature. The projection of this slope to zero fluidity defines a temperature which can be used to clarify transitions in fluid behavior, and to normalize a dimensionless presentation of behavior for the real fluid. This intercept, or critical temperature, t*, occurs in the range of ordinary engineering applications. Use of the simplified model provides convenient expressions for film behavior that is difficult to visualize when numerical or precise viscosity laws are used. Calculations for a power law fluid show that the model produces realistic predictions. © 1990 Taylor & Francis Group, LLC.