UNCONVENTIONAL METHODS FOR INFLUENCING FLUID FLOW PartⅤ Fluid Pressure Transients in a Tapered Line

摘要

The analytical approach used is to divide a smoothly tapered section into a finite n Previous investigations have shown that a liquid-filled tapered tube can be used as a transformer for pulses of pressure or volume flux. This study includes both an experimental and theoretical analysis of the transient wave behavior through an inviscid liquid filled, rigid tapered line subjected to both step and pulse inputs. The primary objective of this study is to determine the applicability of a tapered line to attenuate the pressure surge associated with "water hammer." umber of uniform lines of different characteristic impedances to form an approximation of the distributed parameter model readily solved by digital-computer computation. Three taper functions are studied in detail (linear, linear area and exponential), with two different terminations (long uniform line and reservoir). A step line is also studied, for which the method is exact. To verify the analytical approach and results, experiments were performed using water in a four step line made of copper tubing varying in diameter from 1/2 in to 1 in. A special valve arrangement was designed to insure quick closure with minimum shock. Excellent experimental agreement was obtained. The results show that a tapered section can be used to reduce the pressure surge of "water hammer" when the line is terminated by a reservoir. The reduc¬tion increases with the amount and length of taper.