EVALUATION OF A LINEARLY DAMPED MODEL TO PREDICT THE CLOSING MOTION OF A SPRINGLESS FLAPPER VALVE

摘要

A linearly damped model, based on the application of Newton's second law, was applied to predict the closing time for a springless flapper valve. Viscous damping forces were assumed to be a linear function of the flapper velocity. The model predictions, including a delay time to account for the pressure lag at the flapper valve, were in good agreement with experimental data for a pulse combustor flapper valve. Agreement was obtained by adjusting the dimensionless damping coefficient; however, data for two flappers, which differed only in mass, were found to require different values of the dimensionless damping coefficient. It was concluded that a universal dimensionless damping coefficient can not be determined; therefore, experimental investigations would be necessary to determine the coefficient for a given valve geometry. The potential danger of using a linearly damped model with an incorrect value of the damping coefficient is demonstrated by the range of closing times presented. The present study should be a useful contribution to future modeling of flapper valves and other springless valves.