Structural Design And Propellant Performance Of A Horizontal Micro-thruster

Compared with traditional vertical micro-thruster,the horizontal micro-thruster has potential advantages in engineering application,such as adjustable chamber volume and Lawal nozzle.The paper revolves around integral design of the horizontal micro-thruster merging chamber and nozzle,mainly includes structure design and propellant performance.The optimal design scheme of structure and propellant were carried out in this paper.The specific studies are as follows:The horizontal micro-thruster was consisted of three layers similar to sandwich,included encapsulation layer,chamber layer(combustion chamber and nozzle),ignition circuit layer.Semiconductor bridge(SCB)was used as ignition bridge.Propellant was successfully ignited when external stimulus energy was loaded on SCB,such as constant voltage and current.Combustion product spewed out at high speed through nozzle,resulting in an opposite direction thrust.The SUEX Epoxy Thick Film Sheets were used for fabricating a large aspect ratio structure which consisted of cube chamber and Lawal nozzle.Based on the CFX module of ANSYS Workbench software platform,a three-dimensional simulation model of the horizontal micro-thruster was established.Working state of micro-thruster was simulated,and flow field distribution in the chamber-nozzle was analyzed.Propulsion performance of micro-thruster with different Lawal nozzles was studied by 16 groups of orthogonal experiments.The optimal design scheme of structure was obtained,which length and width of chamber were 1500 ?m,convergence half angle of Lawal nozzles was 40°,diffusion half angle 30 °,width of throat was 250?m,curvature radius of throat was 375?m,width of exit was 1250 ?m.Nano-Al/CuO particles were encapsulated into nanoparticles by electrospray process(ES)as propellant of the horizontal micro-thruster,into which nanoparticles were uniformly dispersed.In order to increase propulsion performance of micro-thruster,the energetic binder such as nitrocellulose(NC),RDX,HMX,ammonium perchlorate(AP)and CL-20 were introduced into the nanothermite composites to adjust propulsion performance and combustion characteristics of nanothermite.The composites were systematically characterized by scanning electron microscopy(SEM),differential scanning calorimetry(DSC),pressure cell and micro impulse testing stand.The optimized Al/CuO-based nanothermite composites with AP showed enhancing properties compared to composites with RDX,HMX,CL-20,which output capacity was increased without weakening ignition delay time.In summary,the optimal design scheme of ropellant was Al/CuO/NC-2.5%/AP-7.5%.