Joseph Zimmerman CU Aerospace LLC 9/5/2017 Capstone Senior Design Project Ideas Joseph Zimmerman CU Aerospace LLC 9/5/2017

Summary Brief Company Overview Thermoelectric Waste Heat Recovery (POETS) Pulse Driver Circuit for Plasma Flow Control (related to NASA contract)

CU Aerospace Synopsis CU Aerospace is a high tech aerospace company growing at ≈ 20% per year Founded in 1998 Location: Champaign, Illinois M2 Building (downtown Champaign) Total number of employees (FTE): 12 Partners 6 Founding Partners 4 Jr. Partners Core Technology Business Areas Modeling and Simulation, Plasma-based Technologies, Spacecraft Systems (Propulsion & Software), Laser Systems, Advanced Aerospace Composites, and Aircraft Safety Systems Products BLAZE 7 Multiphysics software, THERMOSYS™ MATLAB/Simulink toolbox, Propulsion Unit for CubeSats (PUC), VascTech sacrificial fibers Principal Customers NASA, Air Force, DOE, Navy, MDA, JTO, NSF, Aerospace Primes

Company Divisions R&D efforts in a number of advanced product areas with focus shift towards product hardware/software… Aerospace Materials (Self-Healing, Sacrificial, & TPS) Modeling & Simulation (3D Multiphysics, Thermal Systems, Optimization Strategies) Plasmadynamics & Laser Systems (Plasma Generation, High Energy, & Diode Lasers) Spacecraft Propulsion (Electric & Solar Sail) BLAZE-VI PUC VascTechTM BLAZETM THERMOSYSTM

Project Idea #1 “Thermoelectric Waste Heat Recovery in Mobile Systems” POETS-sponsored joint MechSE-ECE team POETS: Power Optimization of Electro-Thermal Systems Potential applications in various CUA products Proposed project objectives: Apply thermoelectric effect to convert waste heat from battery-powered supply to stored potential Demonstrate the ability of thermal energy harvesting to extend the operational life of the mobile power supply Consider impact on size, weight, and practicality of the mobile system

Turbulent Separation Control Today VGs on B737-700 Passive flow control remains method of choice for commercial aircraft VGs configured for takeoff, landing (~1-3% of flight time) Cruise penalty Most active actuation approaches suited for either low-speeds or high-complexity

Background Innovative Concept - Cyclotronic Plasma Actuator Result: Low-Complexity, On-Demand Vortex Generator Focused E Field Thermal-based actuation of boundary-layer flow Lorentz force coupling of arc filament and magnetic field to produce angular velocity Sweeping arc-filament plasma for vortex formation and enhanced mixing Turbulent boundary-layer separation control

Arc Breakdown Visualization High-speed video of arc breakdown (Ansell, UIUC) Acquired at 100,000 fps, playback 10 fps (1/10,000 real-time) Arc breakdown every 0.5 seconds in playback Correlates to 20 kHz driving frequency of AC circuit

Project Idea #2 “Tunable Pulse Circuit for Plasma Flow Control” CUA-sponsored ECE-team (2-3 people) Relates to joint CUA-UIUC NASA-funded program Seeking improved compact, higher power circuit for atmospheric arcs in plasma flow control actuators Proposed project objectives: Design controller & transformer modules as compact circuit for UAVs (< 250 cm3 for both modules) 100-150 W input, 24-36 VDC (battery) supply Demonstrate tuning (5-50 kHz, varied duty cycle) Analyze circuit efficiency Test / demonstrate circuit with CUA benchtop testbed actuator

Questions?

Back-up Slides for Discussion

Testbed Design and Benchtop Experiments Goals: Improve actuation authority with increasing power, understand actuation properties with design Multiple electrode and permanent magnet configurations Power scaling of circuit AC driving frequency and amplitude GBS Minipuls 2.2 Max 20 kVp-p driving voltage Max 60 mA current output 5-20 kHz driving frequency 0-100% duty cycle control Burst frequencies 0-400 Hz Alternative benchtop approaches: Investigated so far: 60 Hz, RF Future work: pulsed DC GBS Minipuls 2.2

Testbed Configurations Various coaxial formats applied Excitation mechanisms: 5-20 kHz AC pulse, burst mode 60 Hz bipolar 13.56 MHz 13.56 MHz excitation Modified commercial spark-plugs Large cavity Reconfigurable coax Etched PCB w/ embedded magnet

Embedded Magnet Concepts Blown Arc Coax Top AC Side B-field Bottom Flow E-field Etch electrode patterns on copper-clad circuit board (chemical etch or CNC mill) Attach / embed ring, disc, or bar magnet below board Initial bench test with copper-clad FR4 Can be applied to alumina substrate (samples of curamik® obtained) Potential for integrated cooling / simplified circuitry

60 Hz Excitation vs. Voltage Cyclotronic plasma actuator using 60 Hz bipolar excitation. Plasma pulses at 120 Hz (Tplasma = 8.33 ms). Exposure time is 1/15 s (66.7 ms, ~8 plasma pulses). 0.125” diameter inner electrode 110 copper rod w/ rounded at the tip, the is a 0.25” I.D. zinc-plated brass outer electrode, and the insulator is nonporous alumina ceramic. Center electrode tip is positioned 0.125” below the outer electrode, recessed in the alumina tube such that the rounded tip is positioned approximately 1/32” above the alumina. At low primary voltages (just above breakdown), the plasma takes on a filamentary appearance. As voltage increases (and also the plasma current) the rotation rate increases and the appearance becomes more disc like.

V-I Results 13 kHz (GBS Minipuls) 60 Hz (12 kV transformer) Readings from Minipuls Board, ACDelco Tektronix P6015 HV Probe, IridiumIX Pearson 411 Current Monitor, IridiumIX Similar Vpk-pk across sparkplug at breakdown Voltage drops as plasma impedance changes with increased current

Minipuls V-I Results ACDelco, 4 mm gap Iridium IX, 2.5 mm gap 5.2 kHz

Comparison of Arc Rotation with Actuator Configurations Case 1 Case 2 Case 3 Case Spark Plug Magnet Dimensions Centerline B-Field (G) Arc Rotation Rate (RPM) 1 NGK Iridium IX #3521 (2.5 mm gap) 1.5” OD x 0.75” ID x 0.75” Th. 675 6,173 2 3.0” OD x 0.75” ID x 0.5” Th. 2250 9,804 3 3.0” OD x 0.78” ID x 1.0” Th. 2500 10,638 4 ACDelco #41-902 (4 mm gap) 3,788 5 4,505 6 4,762 Video acquired at 5,000 fps with playback 60 fps (1/83 real time) Arc forcing, rotation rate dependent on coax, magnet, and circuit configuration Configuration can be tailored to change actuation effect or in-situ variation in arc rotation (for electromagnet)

Flat Plate Velocity Profiles Similar profile upstream of actuation Local velocity defect from actuation Marginal effect on unactuated flow Flow recovery and increased BL momentum Boundary-layer profiles: Compare to effect of passive VGs (Velte et al., 2009)

Streamwise Flow Field Development Actuation induces development of shear layer Concentrated vorticity deflected away from wall Subsequent increase in unsteadiness in velocity (σV) Suggests enhanced mixing of flow field Strategic placement of actuators is important! Additional work planned to investigate control of separated BL Subsequent study will characterize three-dimensional structure, use on airfoil model Max unsteadiness Max vorticity

VG and Plasma Recovery Comparison VG Strip Single VG Single VG Single Cyclotron (Underpowered) Single Cyclotron (Underpowered) No Control DBD Effects of plasma actuator qualitatively similar to conventional VG Plasma actuator underpowered resulting in lower difference in ΔCp VG may be oversized for application (h > δ) Phase I electronics limited power input  significantly increase power/current to plasma in Phase II to obtain similar VG ΔCp performance while retaining on-demand actuation