EHD Pump - spacegrant.colorado.edu · Mission Overview • Mission Overview • Organizational...

EHD Pump Critical Design Review

University of Nebraska–Lincoln

NASA Goddard Space Flight Center

December 7, 2012

Mission Overview

Mission Overview

• Mission Overview

• Organizational Chart

• Theory and Concepts

• Concept of Operations

• Expected Results

Mission Overview

• Goal statement: The total mission goal is to implement known

and experimental EHD technology in thin-film evaporation

techniques for the purposes of two-phase flow in microgravity.

To verify success of the experiment, we will require data on

fluid flow and temperature from multiple sources.

• We expect high values of thermal transfer coefficients derived

from total heat fluxes on the payload target.

• Results will be used in designs of a similar long-term

experiment that will be held on the ISS. Future applications

include EHD pumps for onboard circuits and microprocessor

integration.

Mission Overview

• Multidiscipline Engineering Collaboration

– GSFC: Experiment Design and Fabrication

– University of Nebraska–Lincoln Aerospace Club:

Experiment Operations/Structure/Subsystems:

• Data Acquisition

• Power Distribution

• Flight Operations

• Structure

• Program Objectives

– EHD Thin Film Evaporation micro-gravity data in

support of ISS Microgravity Experiment Science Review

Micro-Scale EHD • Science Goals: ISS Experiment Preliminary

– Effects of gravity of interaction of flow

fields and electrical fields with and without

phase change

– Effects of gravity of electrical charge

generation in meso- and micro-scale

– Effects of gravity on electrically driven film

boiling

• Applications:

– EHD pumps for on-board processors

– EHD pumps for micro- and nano-scales

– High heat flux thermal control

– Multi-functional Plates

Micro-Scale EHD

• The effects of gravity on the

interaction of electric fields and

flow fields in the presence of

phase change in small and large

scales.

• The effects of gravity on the net

electrically generated two-phase

flow rate in small and large

scales.

• The effects of gravity on

electrically driven film boiling

(includes extreme heat fluxes).

• Convective boiling heat transfer

coefficient in low mass flux

levels in the absence of gravity.

Theories of Operation

• Electrophoretic: charge generation by electro-chemical reaction

• Liquid Pumping

• Function of electric field, temperature & fluid quality

• Di-electrophoretic: take advantage of permittivity gradients (e.g,

two phase flow)

• Phase & Fluid Management

• Thin Film Evaporation

• Electro-striction: Compressible Flow

EHD Force Components

EHD Electrophoretic Force Generation

Asymmetric Geometry leads to higher pressure head: configuration is

impractical for spacecraft applications

EHD Electrophoretic Force

• Coulomb (electrophoretic) force generated by:

• Apply discrete electric field to dielectric fluid using

asymmetric electrode geometry

• Electrolytes in fluid subject to dissociation-recombination

reaction that favors dissociation in presence of electric field

• Attraction of hetero-charges to electrode generates flow

• Electrodes in wall; less asymmetry - lower pressure head

generated

FLOW

L1

L3 L2 L4

Concept of Operations

t ≈ 15 min

Splash Down

t ≈ 1.6 min

Altitude: 91 km

Power on EHD Pump

-G switch triggered

-All systems on

-Begin data collection

t = 0 min

Apogee

t ≈ 2.8 min

Altitude: ≈115 km

End of Orion Burn

t ≈ 0.6 min

Altitude: 52 km

Power to resistors

t ≈ 5 min

End Experiment

Altitude

t ≈ 5.5 min

Chute Deploys

Concept of Operations

Event Action

Launch G switch triggered → Arduino powers on

End of Orion Burn • Send power to platinum resistors

• Data logger and sensors active, collecting data

Time ≈ 1.6 min Power to EHD Pump experiment

End Experiment

• EHD Pump and resistors powered off

• Data logging stopped and sensors inactive

• Arduino in idle state

High-Range Accelerometer Data

High-Range Radial and Tangential Acceleration

Expected Results

• For each of the RTDs in the experiment, the

voltage will be stored and used to calculate the

heat transfer coefficient of the experiment.

• We are measuring the two phase heat transfer

coefficients for thin film liquid boiling using

EHD conduction technique. We expect to see

heat transfer coefficients above 150 W/cm2 · K

Design Description

Changes Since PDR

• Battery Container

– PDR: Batteries lay on their sides, arrayed around the

center

– CDR: Batteries stand up, arrayed circularly

Changes Since PDR

• Dampening

– PDR: Piston-Cylinder

with internal secondary

dampening

– CDR: Piston-Cylinder

with external vibration

dampening, alternative

material

Changes Since PDR

• Double Containment for

Fluids

– To counter the possibility of the

dielectric fluid leaking, the hose

connecting the experiment and

fluid reservoir will have a

secondary containment

implemented.

Changes Since PDR

• Si Wafer Support

– PDR: 0.5 inch Sorbothane

pad for vibrational

dampening

– CDR: Rapid prototyped

plate with access for RTDs

De-Scopes and Off-Ramps

• Scope has not changed since PDR

• No off-ramps

– No “high risk” components–thorough testing with

GSFC to verify

Mechanical Design Overview

Physical Models

Battery Array

Electronics and Fluids System

Experiment System

Battery Array

• 24 NiMH batteries

• Two 9-volt batteries

• Custom-made battery housing

– Rapid prototyped

• Connects NiMH batteries in

series

Electronics and Fluids Systems

Fluid Reservoir

Power Supply

Arduino, Sensors, OpenLog

Z-axis accelerometer

Experiment Sensors Power

Supply

G-Switch

Experiment System

• Two stages of dampening

– Piston-Cylinder System

– Internal Vibration System

• Experiment housing

Stage 1 Dampening

• Experiment system is

constrained on both sides

by the Piston-Cylinder

system

• The pistons remains static,

allowing the experiment

system to move axially

• Dampening materials

absorb most of the

impulses in all directions

Stage 2 Dampening

• Primary purpose is to absorb

vibrations

– Absorbs most of the

vibrations

• Constrains the experiment

housing in all directions

with dampening material

• Side tabs keep experiment

aligned axially

Experiment Housing

• Contains the EHD pump and

sensors

• Two electronic ports

– 25-pin connector for thermal

resistors located underneath

the EHD

– Power connector for EHD

• Two fluid ports for inflow

and outflow

• Vacuum-sealed

Electrical Design Elements

• Control subsystem

– Power

– Controls

– Canister sensors

• Experiment subsystem

– Power

– Heater

– EHD pump

– Sensors

Changes Since PDR

• Finalized canister sensor models

• Changed activation method to 1SYS.1

• Addition of external ADC

• Replace multiplexor with protoshield

Controls

• Power: rechargeable batteries

– Tenergy 9V NiMH 250mAh

• x2, in parallel

• Three PCB assemblies

– Arduino, sensors, data

– Z-axis accelerometer

– G-Switch

Controls Block Diagram

Arduino Assembly

• Arduino Mega 2560 R3

– Manages power distribution to experiment

– Interface to all sensors

– Logs data to storage

– Powered on before flight: 1SYS.1

• Protoshield

– “Breadboard” stacked on top of Arduino

– Canister sensors, OpenLog are soldered on

Protoshield

• OpenLog

– Connected to Arduino

• Serial connection @ 57.6 Kbps

– Flash storage: 1GB microSD

– Logs any data received from serial

• G-switch

– Signals launch

– Determines when timed events begin

Protoshield

• XY-axis accelerometers

– Analog Devices Inc.

– High-range model: AD22284-A-R2

• ± 37g

– Low-range model: ADXL203CE

• ± 1.7g

– Both sensors on one PCB

– Six lines

• High/low X analog outputs

• High/low Y analog outputs

• VCC (+5V), GND

Protoshield

• Pressure sensor

– Honeywell Sensing and Control

– ASDX015A24R

– 0 to 15 psi range

– Three lines

• Analog output

• VCC (+5V), GND

Protoshield

• Temperature sensor

– National Semiconductor

– LM50CIM3/NOPB

– Range of -40° to 120°C

– Three lines

• Analog output

• VCC (+5V), GND

Z-Accelerometer Assembly

• Analog Devices Inc.

• High-range model: AD22279-A-R2

– ± 35g

• Low-range model: ADXL103CE

– ± 1.7g

• Both sensors on one PCB

• Four lines

– High/low Z analog outputs

– VCC (+5V), GND

Experiment Subsystem

• Power

• Heater

• EHD Pump

• Sensors

• External ADC

Experiment Block Diagram


• Power

– Batteries

• Tenergy 1V NiMh 10C High Drain

• Rechargeable 2/3A 1600mAh

• x24, in series

– Experiment power supply

• Pico Electronics Series VV, part 48VV3

• Input: 15 to 48V

• Output: 450 to 3000V, max 2.667mA

– Wheatstone power supply: TBD

• Must provide highly stable, constant voltage


• Resistive heater

– Platinum resistors

– Heat silicon wafer

• EHD Pump

– Provided by GSFC

– 2000V at < 1mA

• Sensors

– Provided by GSFC – models TBA

– Pressure sensor

– Flow meter


• Sensors

– Temperature

• x20 RTD sensors

– Very accurate nominal resistance

• Individual Wheatstone bridge circuit per sensor


• External ADC

– Recent development: Arduino ADC is undesirable

• Questionable noise levels

– Simple on-chip ADC

– Additionally from multiplexor?

– Long signal wire travel

• Low resolution: 8-bit

– 1024 values

– 1V reference: ~ 1mV steps


• External ADC

– Proposed model: Texas Instruments ADS1258-EP

• 48-pin IC

• 24-bit resolution

– 1.68 million values

– 5V reference: 298 nV steps

• 16-channel

– Eliminates the need for external multiplexor

– 23.7 kSPS per channel

– All channels sampled in 700 μs – theoretical 1.4kHz sample rate

• Low-noise emphasis

• Digital communication with Arduino via SPI


• External ADC

– Implementation

• Noise minimization

– Converting on-PCB with Wheatstone bridges

– Physically relocate near experiment

» Only digital signals to Arduino travel significant distances

• May use multiple chips depending on sensor quantity

– Compact size: 7.2 mm square

– Still less space compared to mux

Software Design Elements

• Written in C for Arduino

– Augmented using open-source libraries

• TimeAlarm: event scheduling

• Serial communication

• Major tasks

– Time-based power distribution

• Output power-on and -off signals at certain flight times

• Controls experiment, heater

Software Design Elements

• Major tasks

– Read sensor data

• From experiment, canister

– Log data to storage

• Output to OpenLog over Serial

Software Flowchart

Time-Based Events

• Using TimeAlarm library

– Pseudo-realtime event scheduling

– One-second precision

• Events at certain times

– Power on resistive heater

– Power on experiment

– Power off experiment and resistive heater

Prototyping/Analysis

Battery Case FEA

• Solidworks Finite

Element Analysis

on Battery Case

• Material: ABS

(acrylonitrile

butadiene styrene)

Property Value Units

Young’s Modulus 2000 MPa

Poisson’s Ratio 0.394 N/A

Shear Modulus 318.9 MPa

Tensile Strength 30 MPa

Density 1020 kg/m3

Fluid/Electronics Base FEA

• Solidworks Finite

Element Analysis

on load carrying

support

• Material: High

Viscosity

Polycarbonate

Plastic


Young’s Modulus 2320 MPa


Shear Modulus 829.1 MPa

Tensile Strength 62.7 MPa

Density 1190 kg/m3

Piston FEA

• Solidworks FEA

on primary load

carrying element

in dampening

system

• Material:

Aluminum 6061

Alloy


Young’s Modulus 69 GPa


Shear Modulus 26 GPa

Tensile Strength 124.1 MPa

Density 2700 kg/m3

Manufacturing Plan

Mechanical Elements

• Battery Canister

– 3D printed here at the University of Nebraska

• Experiment

– GSFC has designed, and plans to manufacture the

actual experiment

– Dampening System and Canister

• Discussions are in progress for GSFC to manufacture the

experiment canister, as well as the dampening system

Mechanical Elements

• Experiment

– Fluid Reservoir

• GSFC plans to manufacture this

• Materials

– 3D printed parts will be printed out of industry

standard ABS plastic

– All custom manufactured metal components will

be made of industry standard 6061 aluminum

Mechanical Elements

• Materials

– Tubing Material has yet to be decided on

– Sorbothane will be used as a dampening material

in our system

• Construction

– All parts put together in final assembly in-house at

the University of Nebraska

Mechanical Manufacturing Plan

Date Event

1/23/2013 Purchase materials and components

1/23/2013 3D print necessary parts

1/27/2013 Begin component machining

1/30/2013 Begin experiment section construction

2/10/2013 Begin experiment subsystem testing

Electrical Elements

• Yet to be manufactured

– Sensor PCB

• Solder sensor boards to single PCB

• Fairly simple: one revision expected

– Wheatstone bridge, ADC circuit

• May require 2 or 3 revisions

• Yet to be procured

– Batteries for controls and experiment

– Experiment, Wheatstone power supply

Electrical Manufacturing Plan

Date Event

1/25/2013 Purchase remaining components

1/30/2013 Print finalized circuit boards

2/5/2013 Begin Tier 2 construction


Software Elements

• Simple proof-of-concept completed

– Log 20 thermistors to storage

• To be completed:

– Logging of additional sensors

– Time-based events

• No inter-block dependencies

Software Manufacturing Plan

Date Event

12/21/2012 Complete first code iteration

1/4/2013 Test functionality with all sensors

2/8/2013 Verify reliable event timing


2/17/2013 Finalize code

Testing Plan

Mechanical Testing

• Whole assembly will be manufactured and

assembled, including the canister

• Will be tested at GSFC when put together

• Impact testing to simulate rocket launch forces

and axial force on EHD experiment

• Vibration simulation testing will test energy

transfer to EHD experiment

Sorbothane Test Procedure

• Ran In House tests on Sorbothane’s ability to absorb force

• Track angled at 0.5 degrees from table surface

• Frictionless cart (mass: 0.251 kg) released 33.5 cm up

ramp

• Force sensor at bottom of ramp

• Control experiment done without sorbothane, then a

sorbothane pad was placed as a buffer in front of the force

sensor

Sorbothane Test Results

Run # Time (s) Max force (N) Mean Force (N) Impulse (N*s)

1 0.00515 46.21 24.21 0.13

2 0.00495 44.62 21.91 0.12

3 0.00510 42.60 24.10 0.13

4 0.00520 40.68 23.14 0.12

5 0.00530 40.25 22.91 0.12

Run # Time (s) Max force (N) Mean Force (N) Impulse (N*s)

1 0.01020 17.58 9.57 0.10

2 0.01020 16.82 9.47 0.10

3 0.01090 16.72 9.01 0.10

4 0.01069 17.21 9.18 0.10

5 0.01140 14.62 7.92 0.09

With Sorbothane

Without Sorbothane

• Test ran with 1 kg mass added to cart with Sorbothane

buffer in place

– Force: 35.35 N

Without Sorbothane

With Sorbothane

Electrical Testing

• Ensure no current without WFF

• Verify experiment PSU signaling

– Interaction with software

• Verify sufficient battery life for experiment

and controls

– Much higher than time of flight and pre-, post-

flight buffer

• Verify sensor operation and data validity

• Testing planned for winter break

Software Testing

• Ensure time-based events fire at correct time

– Especially Arduino-to-experiment PSU signaling

• Test G-switch polling

• Verify that minimum sampling rate is

maintained

– Prototype software: ~600 Hz

• Testing planned for winter break

Power Risk Matrix

• EHD pump does not operate if –

– Risk 1: EHD power supply fails

– Risk 2: EHD battery is discharged before launch

Risk 1, 2

Possibility

Conse

quen

ce

Controls Risk Matrix

– Risk 1: Experiment failure if Arduino does not signal EHD PSU at appropriate time

– Risk 2: Loss of data precision if the Arduino cannot sample sensors rapidly enough

– Risk 3: Unable to log all data if multiplexor introduces compatibility issues with

sensors

– Risk 4: Inaccurate data if vibrations cause loose connections

– Risk 5: Erroneous data if programming faults exist

Risk 1, 3

Risk 5

Risk 4

Risk 2

Possibility

Conse

quen

ce

Experiment Risk Matrix

– Risk 1: Entire experiment fails because silicon wafer fractures

– Risk 2: Working fluid leakage

– Risk 3: Loss of working fluid due to container integrity failure,

reservoir integrity failure, or seal failure.

– Risk 4: Experiment loses power due to electrical connection

malfunctions.

Risk 1

Risk 4 Risk 2

Risk 3

Possibility

Conse

quen

ce

Structure Risk Matrix

– Risk 1: Experiment fails if structure platforms fail to support

components

– Risk 2: Excessive vibration along with dampening failure causes

experiment to lose structural integrity.

– Risk 3: Dampening material acts unpredictably, causing greater

impulses to translate through.

Risk 1

Risk 2, 3

Possibility

Conse

quen

ce

User Guide Compliance


• Mass

– Payload mass: 10.09 lbs

– Total mass: 17 lbs

• Center of Gravity

– X = -0.016 in

– Y = -0.027 in

– Z = 4.93 in


• Rechargeable NiHM batteries

– Tenergy 2/3 A, 1600 mAh (x24)

– Tenergy 9V, 250 mAh (x2)


• 1.SYS.1 activations

system by WFF

– Arduino powered on by

WFF at T-2 min

– WFF will have full control

over control power

– Once controls are powered

off, so will the entire

experiment

Project Management Plan

Schedule Date Event

1/18/2013 Final Down Select - Flights Awarded Legend

1/18/2013 Stage 2 Funding Proposal submitted to NASA NE Project Milestones

1/23/2013 Order Components and Construction Materials COSGC Expectations

1/25/2013 Begin Payload Subsystem Construction

1/25/2013 Online Progress Report 3 Due

2/15/2013 Individual Subsystems Testing Reports Due

2/25/2013 Start Subsystems Integration

3/12/2013 Online Progress Report 4 Due

3/29/2013 Payload Subsystem Integration and Testing Report Due

4/2/2013 Begin Full Payload Sctructural Test (Vibration, Vacuum, etc)

4/15/2013 RockSat Payload Canister sent to customers

4/26/2013 First Full Mission Simulation Test Report Due

6/3/2013 Launch Readiness Review Presentations

6/12/2013 Travel to Wallops Flight Facility, 1st Group

6/18/2013 Travel to Wallops Flight Facility, 2nd Group

6/14-18/2013 Integration/Vibration at Wallops

6/20/2013 Launch Day

Monetary Budget Section Part Material Material Subtotal (USD)

Manufacturing Subtotal

(USD)

Experiment 2x Dampening base plate Aluminum 33.26 150

2x Inner dampening plate Aluminum 52.26 275

Experiment housing shell Aluminum 45.68 350

2x Experiment housing plate Aluminum 66.52 240

Computer/resivior mounting plate Makrolon 27.89 65

2x Stage 1 Dampening pads Sorbothane 91.26 0

2x stage 2 dampening pads Sorbothane 68.17 0

Miscellaneoud Dampening pads Sorbothane 52.78 0

2x Pipe elbows Aluminium 35.46 0

Hardware

16x Nuts Steel 11.36 0

4x Threaded rod Steel 6.74 0

30x SHCS Steel 28.71 0

2x Copper O-Ring Copper 30.42 0

Printed Parts

2x Piston Wall ABS Plastic 56.92 210

Lower Battery Plate ABS Plastic 42.13 250

Upper Battery Plate ABS Plastic 38.75 250

Subtotal 688.31 1790

Total Cost 2478.31

Monetary Budget Section Part Quantity Unit Price (USD) Subtotal (USD)

Electrical/Controls Arduino Mega2560 Rev3 1 50.69 50.69

Mux Shield 1 24.95 24.95

Payload Pressure Sensor 1 62.09 62.09

Payload Temperature Sensor 1 1.06 1.06

Payload Low Range Z-Axis Accelerometer 1 18.04 18.04

Payload High Range Z-Axis Accelerometer 1 12.83 12.83

Payload Low Range X&Y-Axis Accelerometer 1 21.71 21.71

Payload High Range X&Y-Axis Accelerometer 1 18.03 18.03

Nickel Tabs 30 0.1 3

Flow meter (donated) 1 0 0

Subtotal 161.71

Tier 2 Reservoir 1 donated 0

Tubes 2 20 40

PCBs 3 10 30

Subtotal 70.00

Power Systems 24x Tenergy 2/3A 1600mAh 24 1.68 40.32

2x Tenergy 9V 250mAh 2 4.19 8.38

Power Supply 1 136.24 136.24

Subtotal 184.94

Grand Total 2894.96

Mass Budget

System Item Mass (g) Quantity Total Item Mass

kg pounds Total Payload Mass

Battery pack 1.2V battery 23 24 0.55 1.22 kg pounds

9V battery 50 2 0.10 0.22 4.58 10.09

Base Plate 116.7 1 0.12 0.26

Top Plate 75.53 1 0.08 0.17

Nickel Tabs 0.22 47 0.01 0.02

Total 0.85 1.88 Center of Gravity

Required

Level 2 Base Plate 150 1 0.15 0.33 cm inches

Reservoir 600 1 0.60 1.32 X 0 ±0.5 0 ±0.5

Power Supply 50 1 0.05 0.11 Y 0 ±0.5 0 ±0.5

Wheatstone 20 1 0.02 0.04 Z 12.688 ±0.5 4.75 ±0.5

Arduino 36 1 0.04 0.08 Current

Mux Shield 36 1 0.04 0.08 X -0.04 -0.016

Accelerometer 20 2 0.04 0.09 Y -0.07 -0.027

Wiring 70 1 0.07 0.15 Z 12.53 4.93

Total 1.00 2.21

Mass Budget

Experiment Item Mass (g) Quantity Total (kg) Total (lbs)

Stage 1 Piston 109.89 2 0.22 0.48

Cylinder 53.07 2 0.11 0.23

Bolt 2.04 8 0.02 0.04

Nut 0.54 8 0.00 0.01

Sorbothane 291.64 2 0.58 1.29

Plate 43.04 2 0.09 0.19

Total 1.02 2.24

Stage 2 Plates 74.64 2 0.15 0.33

Sorbothane 134.71 2 0.27 0.59

Sorbothane Tabs 1.06 4 0.00 0.01

Bolt 10.13 4 0.04 0.09

Nut 2.07 8 0.02 0.04

Total 0.48 1.06

Mass Budget

Experiment Housing Cap 187.84 1 0.19 0.41

Brace 250.8 1 0.25 0.55

Base 231.38 1 0.23 0.51

EHD 120.24 1 0.12 0.27

Thermal sheet 180.73 1 0.18 0.40

Hex screw 0.67 8 0.01 0.01

elbow joint 1.52 2 0.00 0.01

power port 0.56 1 0.00 0.00

pin connector 47.76 1 0.05 0.11

Total 1.03 2.27

Misc Hose 4.57 2 0.01 0.02

nut 1.62 34 0.06 0.12

All-thread 31.73 4 0.13 0.28

middle AT 6.35 1 0.01 0.01

Total 0.20 0.44

Power Budget Device Voltage (V) Current Draw (mA) Time Running (min) mAh

Arduino 9 10 15 2.5

XYZ Accelerometer 5 10 15 2.5

Pressure Sensor 5 5 15 1.25

Temp sensor 5 5 15 1.25

OpenLog 5-3.3 10 15 2.5

MUX Shield 5-3.3 5 15 1.25

Subtotal 11.25

Total Available 500

Device Voltage (V) Current Draw (mA) Time Running (min) mAh

WheatStone Bridge Circuit 5 300 5 25.00

Power Supply 28 3 5 0.25

EHD Components 2000 3 5 0.25

Thermal heaters 28 500 7 58.33

Flow meter 5 10 5 0.83

Subtotal 84.67

Total Available 1600

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