ON THE APPLICATION OF OLEO-PNEUMATIC ACCUMULATORS FOR THE PROTECTION OF HYDRAULIC TRANSMISSION LINES AGAINST WATER HAMMER - A THEORETICAL STUDY

Abstract

The remarkable advance in hydraulic and electro hydraulic power systems resulted in producing high response control valves of very short settling time. The actuation of these valves rapidly opens or closes the hydraulic transmission lines, which may produce a severe pressure surge. This paper is dedicated to evaluate the applicability of oleo-pneumatic accumulators for the protection against this phenomenon. A lumped parameter model was developed for the transmission line, assuming different number of lumps, considering the effect of line resistance, inertia and capacitance. The validity of lumped parameter models is evaluated by comparing theoretical results with published experimental results. The paper presents the derivation of a closed expression for the size of the hydraulic accumulator needed to protect the transmission line against the destructive effect of the pressure surge. The study showed that the implementation of an accumulator of convenient size reduced the duration and amplitude of the transient pressure oscillations.