GLAST Thermal Model Overview - Stanford University · GLAST Thermal Model Overview Jeff Wang...

15
1 GLAST LAT Project LAT Systems Engineering Review, 11/19/02 GLAST Thermal Model Overview Jeff Wang Lockheed Martin Advanced Technology Center LAT Thermal Systems Engineer [email protected] Gamma Gamma - - ray Large ray Large Area Space Area Space Telescope Telescope

Transcript of GLAST Thermal Model Overview - Stanford University · GLAST Thermal Model Overview Jeff Wang...

Page 1: GLAST Thermal Model Overview - Stanford University · GLAST Thermal Model Overview Jeff Wang Lockheed Martin Advanced Technology Center ... – Radiator, X-LAT and solar array SINDA

1

GLAST LAT Project LAT Systems Engineering Review, 11/19/02

GLAST Thermal Model Overview

Jeff WangLockheed Martin Advanced Technology CenterLAT Thermal Systems Engineer

[email protected]

GammaGamma--ray Large ray Large Area Space Area Space TelescopeTelescope

Page 2: GLAST Thermal Model Overview - Stanford University · GLAST Thermal Model Overview Jeff Wang Lockheed Martin Advanced Technology Center ... – Radiator, X-LAT and solar array SINDA

2

GLAST LAT Project LAT Systems Engineering Review, 11/19/02

LAT Thermal Systems OverviewLAT Thermal Systems Overview

012860.25208

Survival

W602523LAT Process Power

On-Orbit Thermal Environment and LAT Process Power

W/m2

W/m2Units

12860.25208

Cold

1419Solar Flux0.40Earth Albedo265Earth IRHot MLI thermal shielding surrounding

ACD, Grid Box, Electronics

X-LAT Plates shunt Electronics process power to Radiators

LAT Thermal OverviewLAT Thermal Overview

Active VCHP control allows for variable Radiator area to maintain constant interface temp to LAT

Total Max Power = 602 + 48 = 650 W

Page 3: GLAST Thermal Model Overview - Stanford University · GLAST Thermal Model Overview Jeff Wang Lockheed Martin Advanced Technology Center ... – Radiator, X-LAT and solar array SINDA

3

GLAST LAT Project LAT Systems Engineering Review, 11/19/02

Thermal System Detailed DesignThermal System Detailed Design

• Radiators– Two panels, parallel to the LAT XZ-plane– Size per panel: 1.85 m x 1.46 m = 2.7 m2

– Construction• Aluminum honeycomb structure

• 6 variable-conductance heat pipes on each Radiator panel

– Provide active feedback control of grid temperature through VCHP’s

• Heat Pipes– Design

• Constant-conductance heat pipes on the Grid Box

• Ammonia working fluid• Extruded aluminum• Multiple axial groove casings

– Top Flange Heat Pipes (not shown)• Isothermalize grid structure

– X-LAT Heat Pipes• Remove waste heat from electronics• Connect radiators for load-sharing

– Downspout Heat Pipes• Transport waste heat from grid to radiator

VCHPs

Down Spout Heat Pipes

Radiator and Heat Pipe DetailsRadiator and Heat Pipe Details

X-LAT Heat Pipes

Variable-Conductance Heat Pipes

Page 4: GLAST Thermal Model Overview - Stanford University · GLAST Thermal Model Overview Jeff Wang Lockheed Martin Advanced Technology Center ... – Radiator, X-LAT and solar array SINDA

4

GLAST LAT Project LAT Systems Engineering Review, 11/19/02

Radiator Hot Design Case Heat LoadsRadiator Hot Design Case Heat Loads

0

100

200

300

400

500

600

700

800

9000

900

1800

2700

3600

4500

5400

6300

7200

8100

9000

9900

1080

011

700

1260

013

500

1440

015

300

1620

016

818

Rad1 TotalRad2 TotalRad total(2)

Page 5: GLAST Thermal Model Overview - Stanford University · GLAST Thermal Model Overview Jeff Wang Lockheed Martin Advanced Technology Center ... – Radiator, X-LAT and solar array SINDA

5

GLAST LAT Project LAT Systems Engineering Review, 11/19/02

Thermal Design Changes Since DPDRThermal Design Changes Since DPDR• Radiators

– Moved Radiators closer to Grid to accommodate spacecraft concerns– Increased radiator area from 2.7 sq meters to 2.73 sq meters but added area

in inefficient locations(far from VCHPs)– Provide individual control of each VCHP reservoir-lessons learned from on

orbit experience– Due to lack of definition of minimum solar array view factor, asked for greater

survival heater power budget-affects cost, schedule of TCS components

• Tracker– Add high emissivity black paint to aluminum EMI shield on tracker composite

walls• Increases heat transfer to ACD and increases tile detector assembly

temperatures• Increase heat transfer among tracker towers and reduces the maximum

tracker temperature• ACD

– Change outside layer of LAT MLI blanket from FOSR to germanium black kapton

• Increases tile detector assembly temperatures• Increases maximum tracker temperature

Page 6: GLAST Thermal Model Overview - Stanford University · GLAST Thermal Model Overview Jeff Wang Lockheed Martin Advanced Technology Center ... – Radiator, X-LAT and solar array SINDA

6

GLAST LAT Project LAT Systems Engineering Review, 11/19/02

LAT Instrument and Radiator Assembly Thermal ModelLAT Instrument and Radiator Assembly Thermal Model

• Combined TSS/SINDA Model consists of– External TSS from ACD TSS Model

• (64 surfaces, 2440/2752 active nodes)– Internal TSS includes internals from ACD

and LAT Grid and TKR’s– TSS radiators, XLAT, solar arrays and

vehicle• SINDA Model

– Consists of 11,617 nodes– ACD model from GSFC with Grid and TKR’s

removed (516 nodes)– LAT SINDA model generated from SLAC

ANSYS model (7969 nodes)– Radiator, X-LAT and solar array SINDA

nodes and conductors generated by LMMS

LAT Thermal Model TSS External GeometryLAT Thermal Model TSS External Geometry

Page 7: GLAST Thermal Model Overview - Stanford University · GLAST Thermal Model Overview Jeff Wang Lockheed Martin Advanced Technology Center ... – Radiator, X-LAT and solar array SINDA

7

GLAST LAT Project LAT Systems Engineering Review, 11/19/02

Tracker Thermal ModelTracker Thermal Model

• Current tracker thermal model not adequate– Does not account for radiation heat transfer – Current Thermal Model doesn’t converge during steady state

calculations • Can lead to error in temperature predictions if not understood• Very high conductors indicate some nodes should be lumped together• Some zero conductors

• Developing new thermal model of tracker– Will include radiation heat transfer between tracker with high

emissivity coating(black paint) on tracker walls– Model expected 1/15/03

• Confirmed thermal conductivity of tracker composite walls 297 w/m-K in the Z-direction; 147 w/m-K in plane perpendicular to Z

Page 8: GLAST Thermal Model Overview - Stanford University · GLAST Thermal Model Overview Jeff Wang Lockheed Martin Advanced Technology Center ... – Radiator, X-LAT and solar array SINDA

8

GLAST LAT Project LAT Systems Engineering Review, 11/19/02

Calorimeter Thermal ModelCalorimeter Thermal Model

• Detailed Calorimeter model developed to replace current ~200 node model in LAT– Will be correlated to upcoming component level test– Reduced model (15 nodes) developed for LAT thermal model

• Will be correlated with detailed model• Model due 11/15-currently scheduled for 11/22• Will use to confirm TV cycle time

N6 N4

N2

N3

N5 N1

N7

N8 N9 N11

N10

N12

N13

N15 X+

Y+

N14

Page 9: GLAST Thermal Model Overview - Stanford University · GLAST Thermal Model Overview Jeff Wang Lockheed Martin Advanced Technology Center ... – Radiator, X-LAT and solar array SINDA

9

GLAST LAT Project LAT Systems Engineering Review, 11/19/02

CooldownCooldown of LAT in Thermal Vacuum Testof LAT in Thermal Vacuum Test

With VCHPs kept full open, it takes about 36 hours for the Tracker to reach its lower ATP limit. This also assumes the LAT is in flight configuration, i.e. MLI blankets, Radiators, etc. as designed for flight.

Page 10: GLAST Thermal Model Overview - Stanford University · GLAST Thermal Model Overview Jeff Wang Lockheed Martin Advanced Technology Center ... – Radiator, X-LAT and solar array SINDA

10

GLAST LAT Project LAT Systems Engineering Review, 11/19/02

Calorimeter Calorimeter CooldownCooldown--Current Model PredictsCurrent Model Predicts

Page 11: GLAST Thermal Model Overview - Stanford University · GLAST Thermal Model Overview Jeff Wang Lockheed Martin Advanced Technology Center ... – Radiator, X-LAT and solar array SINDA

11

GLAST LAT Project LAT Systems Engineering Review, 11/19/02

Electronics ModelingElectronics Modeling

• Current definition, used for Delta-PDR

Cold Case Power Dissipation Hot Case Power Dissipation

Bay 12SIU-A

Bay 13Empty

Bay 14Empty

Bay 15EPU-A

Bay 12SIU-A

Bay 13Empty

Bay 14Empty

Bay 15EPU-A

27.97 0 0 13.61 33.78 0 0 16.44

Bay 8SIU-B

Bay 9GASU

Bay 10GASU

Bay 11EPU-A

Bay 8SIU-B

Bay 9GASU

Bay 10GASU

Bay 11EPU-A

0 7.08 7.08 13.61 0 8.64 8.64 16.44-X Side Bay 4

Pwr Dist-BBay 5GASU

Bay 6GASU

Bay 7EPU-A

+X SideSun Side

-X Side Bay 4Pwr Dist-B

Bay 5GASU

Bay 6GASU

Bay 7EPU-A

+X SideSun Side

0 7.08 7.08 13.61 0 8.64 8.64 16.44

Bay 0Pwr Dist-A

Bay 1Empty

Bay 2EPU-B

Bay 3EPU-A

Bay 0Pwr Dist-A

Bay 1Empty

Bay 2EPU-B

Bay 3EPU-A

24.00 0 0 13.61 36.00 0 0 16.44

Ptot: 134.75 Ptot: 170.08TEM/TPS: 9.23 TEM/TPS: 13.02

P(tot): 282.43 P(tot): 378.38

Legend: Notes:GASU Global trigger, ACD, and Switching Unit 1. All power is in wattsSIU Spacecraft Interface UnitPwr Dist Power Distribution BoxEPU LAT Event Processor-A A-side, powered box-B B-side, unpowered cold box

LAT Top View

-Y SideLAT Radiator

+Y SideLAT Radiator

+Y SideLAT Radiator

-Y SideLAT Radiator

LAT Top View

LAT +X

LAT +Y

LAT +X

LAT +Y

Page 12: GLAST Thermal Model Overview - Stanford University · GLAST Thermal Model Overview Jeff Wang Lockheed Martin Advanced Technology Center ... – Radiator, X-LAT and solar array SINDA

12

GLAST LAT Project LAT Systems Engineering Review, 11/19/02

Electronics ModelingElectronics Modeling

• No detailed definition– Only preliminary mechanical layouts– Only preliminary footprints of specific electronics on X-LAT plate– Mechanical lead recently hired to work interface details

• Current definition will define X-LAT heat pipes– Need detailed definition of electronics box design by 12/20

Heat Flow From X-Lat HP's to RadiatorsV0 Combined_LAT_ACD_hot_xtrasol, Third Orbit

-60

-50

-40

-30

-20

-10

0

11212 12212 13212 14212 15212 16212 17212

Time (Seconds)

Hea

t Rat

e (W

atts

)

X-Lat1, Rad1

X-Lat1, Rad2

X-Lat2, Rad1

X-Lat2, Rad2

X-Lat3, Rad1

X-Lat3, Rad2

X-Lat4, Rad1

X-Lat4, Rad2

X-Lat5, Rad1

X-Lat5, Rad2

X-Lat6, Rad1

X-Lat6, Rad2

Page 13: GLAST Thermal Model Overview - Stanford University · GLAST Thermal Model Overview Jeff Wang Lockheed Martin Advanced Technology Center ... – Radiator, X-LAT and solar array SINDA

13

GLAST LAT Project LAT Systems Engineering Review, 11/19/02

VCHP ModelingVCHP Modeling

• Lockheed Martin Software– Converted from heritage to Sinda format– Providing results consistent with Cullimore & Ring routine; will allow

use of commercial software for model delivery– Currently working VCHP control logic; expected by 12/20

• VCHP Modeling– Added reservoirs to TSS model; required for feedback control – Can evaluate hot design case; cold case evaluation difficult without

minimum solar array view factor

• VCHP Control– For normal operations, each heatpipe will be individually controlled

• Requires more heater zones and thermistors• Complicates control logic• necessary for control during all possible orientations(flight experience)

Page 14: GLAST Thermal Model Overview - Stanford University · GLAST Thermal Model Overview Jeff Wang Lockheed Martin Advanced Technology Center ... – Radiator, X-LAT and solar array SINDA

14

GLAST LAT Project LAT Systems Engineering Review, 11/19/02

Verification Test TemperaturesVerification Test Temperatures• Test temperatures set to exercise

subsystem design limits

Page 15: GLAST Thermal Model Overview - Stanford University · GLAST Thermal Model Overview Jeff Wang Lockheed Martin Advanced Technology Center ... – Radiator, X-LAT and solar array SINDA

15

GLAST LAT Project LAT Systems Engineering Review, 11/19/02

Environmental Temperature LimitsEnvironmental Temperature Limits

Component Low Temp Limits (degC) High Temp Limits (degC) Survival (degC)Qual AT Operating Operating AT Qual Low High

Desired -40 -35 -30 +50 +55 +60 -40 +60

Tracker -30 -20 -15 25 30 50 -30 50Calorimeter -30 -20 -15 25 30 50 -30 50TEM* -40 -35 -30 50 55 60 -40 60EPU* -40 -35 -30 50 55 60 -40 60SIU* -40 -35 -30 50 55 60 -40 60Pwr Dist* -40 -35 -30 50 55 60 -40 60GASU* -40 -35 -30 50 55 60 -40 60BEA -25 -20 -15 30 35 40 -40 45TDA -50 -45 -40 35 40 45 -60 45Grid -40 -35 -30 30 35 40 -40 40CCHP's -40 -35 -30 30 35 40 -40 40VCHP's -35 -30 -25 30 35 40 -67 40Radiator Panels -72 -67 -62 50 55 60 -72 60

• Shooting for “Desired” temperature limits• Any deviations from desired limits requires a technical note justifying the change