Post on 25-Feb-2016
description
Thermal Investigation for Accurate Temperature Measurement
Team TCTJTruc Le
Cedric ToguemJonathan Newman
Overview•Mission Goal•Objectives•Science Background•Technical Background •Payload Design
• Electrical• Software
• Mechanical•Payload Development
Mission GoalThe goal is to determine why previous LaACES payloads failed to correctly measure temperature in comparison to NOAA.
ObjectivesMeasure the temperature inside and outside the boundary layerMeasure the temperature with different color coated temperature sensors.Measure the temperature on the inside and on the outside surfaces of the payload.Have the payload returns intact.
Temperature change in the Atmosphere
• Troposphere (0 to 12km) : lowermost atmosphere where temperature decreases from 30 to -80°C• Stratosphere (12 to 48km): second lowermost part of the atmosphere where temperature increases from -80 to 0°C
http://apollo.lsc.vsc.edu/classes/met130/notes/chapter1/vert_temp_all.html
Boundary LayerThin layer of fluid in contact with a solid
body that flows more slowly than the rest of the fluid
As the payload gains altitude in fluid air, the boundary layer around it will be affected by heat transfer processes
http://apollo.lsc.vsc.edu/classes/met130/notes/chapter1/vert_temp_all.html
Heat Transfer ModesHeat can be transferred in three
different ways:- Conduction- Convection- Radiation
http://blogs.saschina.org/morena01pd2016/files/2009/10/ccr.jpg
ConductionTransfer of thermal energy between
molecules due to temperature gradient
The energy flows from a region of higher temperature to a region of lower temperature
Convection
Movement of molecules within fluid
A shallow layer of air in contact with a hotter surface warms by conduction, acquires buoyancy and then rises
RadiationElectromagnetic radiation emitted from the
surface of an object in the form of heat due to the objects temperature
If an object is warmer than its surrounding environment, it will emit more radiation in the form of heat into the surrounding environment than it will absorb in order to attain thermal equilibrium
http://www.tsc.com/irgen/Image7.gif
Test 1: Radiation Test 1Radiation test:
Sun →Electromagnetic radiation → Space →Sensors
The test will consist of different color shielding to reflect the electromagnetic radiation from the sun
http://image.tutorvista.com/content/dispersion
Test 2: Radiation Test 2Radiation Test:The payload circuitry will emit radiation
to the sensor.Distance from the radiation source will
determine the amount of heat dissipated
http://images.google.com/imgres?imgurl=http://www.uos.harvard.edu/images/ehs/radiation
Test 3: Boundary Layer Test
Sensors are placed at different distance from the exterior surface of the payload
Determine how much effect the boundary layer has on the measured temperature
http://www.google.com/imgres?imgurl=http://www.engineering.leeds
Thermal Boundary Layer
Payload DesignPower Source
TemperatureSensorsOp AmpBalloonSat
CPU
Electrical Design
Power Supply
Sensors BallonSat
Electrical Design (lowest level)
Sensors
Sensor Interfacing
Power Supply
Sensors BalloonSat(ADC)Op-Amp0~800mV 2.5~3Vtemperature
5V DC
Sensor Interfacing
Flight Power Supply
12V battery
5V battery
Sensors Op - Amp BalloonSat
Flight power supply
Power BudgetComponent
Current (mA)
Duration (hrs.)
Capacity (mA-h)
BalloonSat 51 (measured)
4 275
RTDs (x7) 1 each (estimated)
4 28
Total 58 4 303
Flight SoftwarePre-Flight and During Flight
Sensor Data
Read
ADC
BalloonSat
Real Time Clock
Write
Read
Memory
Flight SoftwarePost-Flight:
Memory BalloonSat
Read Basic Stamp Editor
Excel
Flight SoftwareOnboard Flight Program:
LoopPause
Read
WriteEnd If/Then
Flight SoftwarePost Flight Program:
AnalyzeRead Transfer to Excel
Exterior Mechanical Design
Interior Mechanical Design
Weight BudgetComponent Weight (g)BalloonSat 66 (measured)Styrofoam Structure 150 (estimated)BalloonSat Styrofoam Attachments
25 (estimated)
Wiring 7.5 (estimated)Booms (if balsa) 3 (estimated)Booms (if plastic) 10 (estimated)Boom attachments 25 (estimated)Sensors 10(estimated)Total 289.5-296.5 +/- 25%
Payload Development PlanMechanical
◦Boom prototyping◦Attachment prototyping◦Impact test to find best design to
store components◦Maintain payload within regulation
Payload Development PlanElectrical
◦Determine best temperature sensor to use
◦Determine best batteries to use and its configuration
◦Design the circuitry of the system◦Determine how well the components
will function in flight climate◦Determine methods of calibration of
the sensors
Payload Development PlanSoftware
◦Determine best way to consume less power
◦Determine if extra memory will be needed and how to access it
◦Determine the timing sequence ◦Determine methods of calibration
Reference1. Clavius: Environment - heat transfer.
http://www.xmission.com/~jwindley/heatxfer.html. November 24, 2009
2. Anne E. Egger "Earth's Atmosphere: Composition and Structure," Visionlearning Vol. EAS 2003. http://www.visionlearning.com/library/module_viewer.php?mid=107
3. Sad Dr Rodrigue – Introduction to physical Geaography. http://www.csulb.edu/~rodrigue/geog140/lectures/thermalstructure.html
4. BASIC Stamp 2p 24-Pin Module. http://www.parallax.com/Store/Microcontrollers/BASICStampModules/tabid/134/ProductID/7/List/1/Default.aspx?SortField=UnitCost,ProductName. November 25, 2009
Questions?