Study On Output Characteristics Of Direct Heat Paraffin Actuator

The main means of space separation and release device include non-pyrotechnics and pyrotechnics.Paraffin drive,as one of the non-pyrotechnics,has the advantages of high safety,convenience and efficiency.In order to study the output characteristics of direct-heat paraffin actuator,this paper established the output theoretical model of directheat paraffin actuator based on the thermodynamic characteristics of paraffin and classical friction theory by making a prototype.The 3D model of the actuator was drawn and a special test bed was built.The heating mode,sealing reliability,system friction,force output and displacement output were studied and analyzed.The main research contents are as follows:(1)The heating mode,driving position,sealing part and overall size of direct-heat paraffin drive are improved.By comparing the heating methods used in aerospace and considering the actual situation,the resistance direct heating type is selected to improve the heating rate,improve the sealing reliability,reduce the input temperature requirement and facilitate the use,which provides a reference for the selection of paraffin drive in the future.(2)By analyzing and comparing the properties of paraffin wax,the driving phase change material more suitable for the test was determined,and the main factors affecting the friction force of direct-heat paraffin drive system were analyzed.A set of system friction test platform was designed and established.Through the system friction test,the friction force of the system was determined to be 51.3N.(3)Based on paraffin thermodynamics,classical friction theory,working principle and material properties of paraffin actuator,a theoretical model of displacement output of direct-heat paraffin actuator based on paraffin heat transfer mechanism was proposed.(4)The influence of different external load,heating temperature and amount of paraffin on displacement output of direct-heat paraffin actuator is studied.With the increase of heating temperature and length of internal paraffin column,the displacement output of direct-heat paraffin actuator increases linearly,but decreases linearly with the increase of external force.Finally,the theoretical model is tested with the experimental data,and the output error of the theoretical model is less than 10%.(5)Before the force output test,FLUENT was used to simulate the heat transfer process of paraffin wax,and it was determined that proper heating time should be guaranteed during the heating process of paraffin wax.The force output test mainly studies the influence of the length of paraffin column and the displacement output on the force output.Under the action of external load,the force output reaches the maximum value when the paraffin in the driving device is all melted without displacement output.The larger the displacement output is,the smaller the force output is.The longer the paraffin column,the greater the force output.The numerical simulation of the experimental data of the force output was carried out by Python,and the scatter diagram of the experimental data was obtained.The experimental error diagram was obtained by comparing with the theoretical plane formed by the force output.It was found that the experimental error was within a reasonable range,and the error could be reduced by increasing the length of the paraffin column later.