Electromagnetic Expulsion of a Cylindrical Body from an Outer Tube - PowerPoint PPT Presentation

Team 2020 Electromagnetic Expulsion of a Cylindrical Body from an Outer Tube NAVAL UNDERSEA WARFARE CENTER

Team ECE Members ME Members Abhishek Dutta, Advisor Jiong Tang, Advisor Alexander Podgorski Joshua Dupont Alexandra Paulakos Nickolai Serebriakov Joseph Slivinski Patrick Haggarty NUWC Contacts Mike Sheahan, Technical & Integration Lead, Michael.E.Sheahan@Navy.mil James Leblanc , James.M.LeBlank@Navy.mil

Background ▪ Main Goal: Expel a Cylindrical Body from a Tube into Water ▪ Main Principle: Induced Electromagnetic Force ▪ Basis: Take last year's proof-of-concept design & improve efficiency/performance ▪ Planned Improvements: more powerful multi-stage firing mechanism, high resolution data capture, & parametric simulation

Background – Schematic ▪ Current Design Schematic ▪ Using a metal pressure boundary outer tube to tank design opposed to last year's submersed plastic tube ▪ Mechanical team is working to optimize all materials & create water-tight hatches Figure 1: Initial Mechanical Layout

Solution ▪ Maximize utilization of space inside the metallic pressure boundary ▪ 2.25" payload within a 2.5" inner diameter tube ▪ Three stages of electromagnetic coils to overcome fluid resistance ▪ Control & data acquisition performed by a microcontroller ▪ Data acquisition on the individual capacitor voltages & coil currents to monitor and refine transients

Pulse Forming Network [PFN] ▪ Gate circuit triggered on command by Microcontroller ▪ Current simulations predict peak power no higher than 9kW ▪ Each bank consists of: ▪ Single capacitor (250V , 30mF) ▪ 1.8kJ stored energy ▪ MOSFET Power Module: ▪ Rated at 800V ▪ 57A continuous, 230A peak ▪ Capable of 14kW continuous and 57kW peak power at 250V operating conditions

PFN (cont'd) ▪ V alues & ESR of the coil is a direct function of wire gauge & number of turns ▪ Physical size of the coil found from the wire gauge & number of turns (for a fixed diameter) State Microcontroller Capacitor Gate Circuit OFF OFF Discharge Disabled ON ON Discharge Disabled CHARGE ON Charge Disabled ARM ON Hold the Enabled Figure 2: Approximated PFN Circuit Setup charge Table 1: Four States of Pulse Forming Network

Coil Design Equation 1: Number of ▪ Control resistance of the coil as a function of wire Turns gauge & length ▪ Control inductance using the found number of Equation 2: turns ESR Resistance Equation 3: Coil Inductance

Coil Design – MATLAB ▪ Restricts ESR to 3Ω ▪ Restricts number of turns based on the ESR ▪ As the number of turns increases: ▪ Wire length increases ▪ ESR increases ▪ As the wire gague increases: ▪ Wire diameter decreases ▪ Resistance increases ▪ Cross-sectional area of the wire decreases ▪ Number of turns increases Figure 3: Coil Inductance & ESR @ 2" coil width

Coil Design – MATLAB (cont'd) ▪ Restricts ESR to 3Ω ▪ Restricts number of turns based on the ESR ▪ As coil width increases: ▪ Number of turns increase ▪ ESR increases ▪ Coil inductance increases Figure 4: Coil Inductance & ESR @ 3" coil width

Charge Controller ▪ Boost Converter ▪ UCC28056Power Factor Controller IC ▪ Converter charges in less than 60 seconds, controller keeps it at a steady voltage ▪ Prototype was built/tested with a DC power supply & worked as intended ▪ Was planning on testing with an AC power supply when returning from Spring Break Figure 5: Charge Controller Circuit

Charge Controller (cont'd) ▪ 115Vac input power will be through a standard NEMA 15-5 wall plug to a C14 AC power inlet module like the back of a PC power supply ▪ Power switch, cartridge fuse, & breaker included as safety isolations ▪ 130VA transformer used as a 1:1 current limiting isolation with additional fuses on output

Microcontroller ▪ An 8-bit Arduino microcontroller would be used to manage control & logging ▪ Three GPIO outputs used for PFN trigger circuits ▪ One GPIO output to control the charge circuit isolation prior to launch ▪ Two GPIO inputs for user control ▪ Serial Communications port to read & record ADC values ▪ An 8 Channel, 24 bit, 256ksps Sigma Delta ADC monitors capacitor voltage & discharge current during launch events ▪ Each stage has a precision bidirectional current shunt in line with the coil to measure injected & flyback current

ME Design – Testing Tank The test tank consists of a • watertight acrylic tank The launch tube is sealed at • both ends by manual watertight hatches • The launch tube is 2.5" ID 316 Stainless Steel pipe with 0.200" wall thickness A flood/drain valve is on the • bottom for loading/launching Figure 6: ME Rig Constructed An equalizing valve & tube are • on top to minimize energy losses to fluid flow Figure 7: ME Rig Model

Coil Carrier Design (ECE team) Final Arrangement: One 3" wide coil, Two 2" wide coils Coil Carriers are 3D Printed From ABS • Plastic Each carrier used 3 subpieces glued • together for printing ease • Three carriers total are wound, then slipped over launch tube Each carrier has wire guides & retention • paths Figure 8: Exploded & Each carrier included interlocking teeth • Transparent view of to maintain orientation during assembly a single carrier & use Figure 9: Final Assembly

Preliminary Material Testing ▪ Tube Materials Tested: (using a carbon steel slug) ▪ Aluminum ▪ 316 Stainless Steel ▪ Titanium ▪ Jump Test: V ertical Launch in Air ▪ V elocity Test: Horizontal Launch in Air ▪ Water Test: Horizontal Launch in Water ▪ Results: ▪ Stainless Steel was found to be the best material ▪ Launching in water reduced payload energy by 1/10th Figure 10: Water Test Setup

ANSYS Simulations ▪ ANSYS allows linking of different simulation systems. ANSYS Maxwell 2D: ▪ ▪ Provides computationally simple itineration's on geometry. ▪ Data on cross sectional field strength, force, acceleration, & flux distribution. ▪ Provides physical simulation of flux linking between coils ANSYS Nexim: ▪ ▪ Provides SPICE analysis of components ▪ Integrates circuit design with magneto dynamic simulation of Maxwell

NEXIM Model Multiple simulation cases ran until useful magnetic performance ▪ determined ▪ Simulation can be validated & refined with test data Stage Turn Gauge Count 1st 300 16Ga 2nd 200 14Ga 3rd 200 14Ga Figure 11: Final NEXIM model, 1st stage Table 2: Final Stage Configuration

Maxwell Convergence Study A convergence study was performed ▪ on both time step & mesh size to determine efficient use of computational resources. Mesh size of 0.010" was determined ▪ to be required for repeatable results, with 0.100" used for rapid design itineration Time step of 0.1ms was chosen ▪ for final results, with 0.5ms used for bulk itineration Figure 12: Time step and mesh size convergence comparisons

Maxwell 2D 2D Transient resulted in a ▪ max payload velocity of 21 ft/s and a peak force of 270 ft-lbs The minimum target payload ▪ speed of 10 ft/s is easily achieved. The buildup of eddy currents ▪ in the stainless steel tube causes a slow field rise & a notable "suckback" effect as the coils stop adding energy to the system Figure 13: Plot of resultant force, velocity, and position from simulation

2D Transient Animation ▪ This simulation shows the field strength & slug position over an 80ms time frame ▪ The coils are the white boxes ▪ The launch payload is pushed out of the tube by the steel slug ▪ At 0ms the first coil is energized ▪ At 32ms the final coil is no longer being supplied additional energy, the fields collapse through the flyback diode ▪ The damping effect of the fluid motion as well as the magnetic suckback of the slug is clearly visible Figure 14: Simulation Animation

Electrically Safe Device Enclosure The 120Vac/250Vdc system are designed to be enclosed in a clear polycarbonate enclosure ▪ for safety Nylon bolts, nuts, hinges, & latches were procured for ease of maintenece while preventing ▪ inadvertent exposure to HV arcs Capacitors, Bus Bar, Current Shunts, MOSFET, & Diodes, as well as control circuitry all ▪ contained within. Two sets of relays disconnect the charge circuitry & discharge the capacitors when the system ▪ is off

User Control Box A control box providing low voltage control circuitry ▪ Four Position Key Switch - ▪ ▪ OFF: All power removed, capacitors paralleled with resistors ▪ ON: Power provided to microcontroller circuitry, capacitors discharge ▪ CHARGE: Power provided to charge circuit ▪ ARM: Launch button enabled Launch Switch ▪ ▪ Initiates microcontroller launch sequence if the key switch is in ARM position