Research On Pressure-shock Absorbing Characteristics Of A Bladder Type Of Pipeline Vibration Absorber

Pressure-shock is an important phenomenon in the working process of the hydraulic servo system of ship steering gear.It will directly affect the steering accuracy,the system stability and the safety of the whole hydraulic servo system.Suppressing pressure-shock is an important approach on improving the performance of ship steering gear control system.Helmholtz resonators and accumulators are generally used for eliminating pipeline vibration.However,Helmholtz resonator which uses the resonance of oil in the expansion chamber to dissipate shock energy,has the limitation of low attenuation ability to absorb pressure-shock and strict frequency restrain.Accumulator can effectively suppress pressure pulsation,but its performance on absorbing pressure-shock is weak.Therefore,it is of great significance to design a new type of pipeline vibration absorber to absorb and suppress the pressure-shock of ship steering gear system.First,combining the structural and functional characteristics of the accumulator and Helmholtz resonator,a new type of pipeline vibration absorber which comprises of a Helmholtz resonator and an embed bladder is designed.This new type of pipeline vibration absorber makes full use of the compressibility of gas to absorb pressure-shock.Its compact structure is very suitable for ship steering gear systems with narrow space.Then,the working principle of the vibration absorber is theoretically analyzed,and its mathematical model is established according to the dynamics theory.The influences of the volume of expansion volume,the number of damping orifices and the prechargepressure of the bladder on its performance of absorbing pressure-shock are analyzed.The frequency characteristics of the damping-load system after installing the vibration absorber are also studied by establishing the dynamic equation of the pipeline system.Next,a simulation model for absorbing pressure-shock is established according to the mathematical model of the vibration absorber.And the influences of the volume of the expansion volume,the number of damping orifices and the precharge-pressure of the bladder on the absorption performance and frequency characteristics of the vibration absorber are respectively studied by using the control variable method,and the relevant parameters are also optimized.Finally,a prototype of the vibration absorber is developed and a test platform is built.The influence of the damping orifice number and the precharge-pressure of the bladder on the performance of vibration absorber is verified by experiments,and the experimental results well agree with the simulation results.After optimization design,the maximum insertion loss of the vibration absorber can reach to 8.18 dB.The optimization design method of the bladder type of pipeline vibration absorber proposed in this paper can effectively improve the performance of the vibration absorber on absorbing pressure-shock,thus improving the performance of the hydraulic servo system of the ship steering gear,and has certain theoretical research and engineering application value.