Thermal Modeling and Correlation of the Space Environments Complex - - PowerPoint PPT Presentation

Presented By

Erik J. Stalcup

Thermal Modeling and Correlation

• f the Space Environments

Complex Vacuum Chamber and Cryoshroud

Erik J. Stalcup NASA Glenn Research Center

Thermal & Fluids Analysis Workshop TFAWS 2018 August 20-24, 2018 NASA Johnson Space Center Houston, TX

TFAWS Interdisciplinary Paper Session

Outline

• Background on the SEC Vacuum Chamber and

Cryoshroud

• Model Description
• Model Correlation

– Integrated System Tests – Bake-out Test

• Summary

TFAWS 2018 – August 20-24, 2018

2

Space Environments Complex

• Formerly known as the

Space Power Facility (SPF)

• Located at Plum Brook

Station in Sandusky, OH

• Houses large-scale test

facilities including the Space Simulation Vacuum Chamber

– Largest vacuum chamber in the world – 100 ft diameter, 122 ft tall – Cryoshroud operates between -250 °F and +140 °F – To be used for Orion EM-1 thermal vacuum test

TFAWS 2018 – August 20-24, 2018

3

Thermal Model Overview

• Thermal Desktop model of vacuum chamber,

cryoshroud, mechanical ground support equipment (MGSE) including fluid model of GN2

• Primary uses:

– Predict MGSE temperatures – Predict heat load on GN2 system

• Includes 96 TD Temperature Measures that represent

test thermocouples

• Steady state correlation with 3 tests

– 2 hot – 1 cold

TFAWS 2018 – August 20-24, 2018

4

Model Description

TFAWS 2018 – August 20-24, 2018

5

Cryofloor Transfer Cart (CTC)

Model Description

TFAWS 2018 – August 20-24, 2018

6

Cryofloor

Model Description

TFAWS 2018 – August 20-24, 2018

7

Flat Beam Interface (FBI) and Cryofloor Interface Adapter (CIA)

Model Description

TFAWS 2018 – August 20-24, 2018

8

Thermal vacuum configuration

Model Description

TFAWS 2018 – August 20-24, 2018

9

Cryowalls, cryoceiling, supply/return pipes

Model Description

TFAWS 2018 – August 20-24, 2018

10

Insulation

Model Description

TFAWS 2018 – August 20-24, 2018

11

Masts

Model Description

TFAWS 2018 – August 20-24, 2018

12

Vacuum chamber

Integrated System Tests

• Two ISTs performed with no MGSE inside the

cryoshroud

– Insulated test: operated at 170 °F for 37 hours – Uninsulated test: operated at 170 °F for 14 days

• Only cryoshroud thermocouples were installed

TFAWS 2018 – August 20-24, 2018

13

IST Correlation: SE Cryowall

TFAWS 2018 – August 20-24, 2018

14

Insulated

>174.88 174.88 173.01 171.16 169.30 167.43 165.58 163.71 161.85 160.00 158.13 156.27 <156.27

Uninsulated

Temperature [F]

IST Correlation: Cryofloor

TFAWS 2018 – August 20-24, 2018

15

Uninsulated Insulated

>174.87 174.87 172.33 169.77 167.23 164.68 162.14 159.58 157.05 154.49 151.95 149.40 <149.40

Temperature [F]

IST Correlation: SE Cryoceiling

TFAWS 2018 – August 20-24, 2018

16

Uninsulated Insulated

>174.67 174.67 173.26 171.86 170.44 169.03 167.63 166.23 164.82 163.42 162.00 160.59 <160.59

Temperature [F]

IST Correlation

• Generally good agreement

between model and test data except cryoceiling intermediate header

• Model predicted large regions of

zero flow

• Adding 5x multiplier to heat

transfer coefficient resulted in much better agreement

TFAWS 2018 – August 20-24, 2018

17

Insulated IST Uninsulated IST Average Error (°F) 0.3 0.6 RMS Error (°F) 1.1 3.7

Bake-out Test

• Bake-out was performed to collect data on chamber

cleanliness, pressure environments, and operations

• Consisted of several hot and cold plateaus
• Correlating from data at -263 °F for 3 days
• Only FBI and CIA inside cryoshroud
• Correlation approach:

1. Reevaluate cryoshroud predictions 2. Adjust contact conductances for MGSE inside and in contact with cryoshroud (FBI, CIA, CTC) 3. Adjust insulation and contact conductances for MGSE outside cryoshroud (masts)

TFAWS 2018 – August 20-24, 2018

18

Bake-out Correlation

• Reevaluating cryoshroud predictions:

– 81 thermocouples on cryoshroud – RMS error = 1.6 °F

• Still acceptable, no changes needed

TFAWS 2018 – August 20-24, 2018

19

Bake-out Correlation

• Adjusting contact conductances

between:

– FBI and CTC – CIA and CTC – Cryofloor and CTC (via isolators) – CTC and chamber floor (via dollies and wheels)

• Utilized SINDA/FLUINT
• ptimization algorithms

– Seeking values of the 4 contact conductances that minimize the RMS error for the 12 thermocouples

• n these structures

– Converged in 43 iterations – RMS error = 5.3 °F

TFAWS 2018 – August 20-24, 2018

20

Bake-out Correlation

• Uncorrelated model predicted warmer temperature outside the shroud

– Increasing insulation emissivity had little effect – As-installed photos showed considerable contact between insulation and cryoshroud

• Utilized SINDA/FLUINT optimization algorithms

– Adjustable parameters of contact conductance between

• Insulation and cryoshroud
• Masts and chamber floor

– Minimizing RMS error for 3 thermocouples (2 on mast, 1 “floating”) – RMS error = 5.0 °F

TFAWS 2018 – August 20-24, 2018

21

Bake-out Correlation

• Overall, model is well correlated
• Potential source of error is the assumption that contact

between large surfaces is uniform, e.g. insulation and cryoshroud, cryofloor and CTC

TFAWS 2018 – August 20-24, 2018

22

Cryoshroud (81 TCs) Interior (12 TCs) Exterior (3 TCs) Total (96 TCs) Average Error (°F)

• 0.9

0.1 4.7

• 0.3

RMS Error (°F) 1.6 5.3 5.0 2.6

Summary

• Model is well correlated, RMS error = 2.6 °F
• Using SINDA/FLUINT optimization algorithms is an

effective way to do model correlation

• Future work

– Transient correlation with bake-out data – Integration with vehicle model and facility FLUINT model

TFAWS 2018 – August 20-24, 2018

23

Acknowledgements

Thanks to the thermal team at NASA GRC and Plum Brook: Jim Yuko, Barbara Sakowski, Jarred Wilhite, Henry Speier, and Erin Reed. Thanks to Justin Elchert and Katie Oriti who developed earlier versions of this model.

Questions?

TFAWS 2018 – August 20-24, 2018

24