A Thermal Hydraulic Model for Expendable Launch Vehicles

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A Thermal Hydraulic Modelfor Expendable Launch
Vehicles

• Michael Berglund
• Delta IV Launch Vehicle Development
• May 16-17, 2000

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Outline

• Point 1 - Correlation with Test Data
• Rocketdyne
• Thermal analysis
• DT-1 RCN
• Point 2 - Design Tool, Test Transient Conditions
• Point 3 - Common Modeling System
• Rocketdyne
• Controls group
• Point 4 - Good Customer Support
• New Parts Specified
• Modeling Hydraulic Systems Using EASY5
• Summary of EASY5 Process

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Easy5 Model of RS-68 Hydraulic System Heat
Transfer Analysis EJ Reott

• ACTUATOR
• VERIFICATION
• VM fluid output temp
• TF2VM
• FO fluid output temp
• (corrected)
• TF2
• Matches MHI Data
• (error /- 3.7)

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Easy5 Model of RS-68 Hydraulic System Heat
Transfer Analysis EJ Reott

• LINE SEGMENT
• VERIFICATION
• Heat transfer from fluid to wall (BTUH)
• QFPI
• Heat transfer from fluid to wall (corrected)
• QFPI11
• Wall temp
• TWPI
• Wall temp (corrected)
• TWPI11
• Matches Calculation
• (error /- 0.4)

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Fluid Temp Rise Across OrificeTVC1, TVC2, RCN

• EASY5 model oil temp rise across orifice
  results
• ?T 76F
• Hand Calculations Oil temp rise across orifice
  (same conditions) results
• ?T 75.9F

6
Fluid Temperature Rise In Flight
7
Development Test Models (major assumptions)

• Development Test Models
• DT_RCN (boundary conditions, spring force)
• DT_TVC (boundary conditions, spring constant
  force)
• DT_Breadboard (valves simulating flow demand for
  all actuators, single valve representing all 4
  engine valves)
• DT_System (TVC, RCN actuators included, single
  valve representing all 4 engine valves)
• Hydraulic_System (same as DT_System but with
  engine valves from Rocketdyne)

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EASY5 DT-1 RCN Model
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RCN Velocity and Stroke
EASY5
DT-1 RCN
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DT-1 RCN
EASY5
11
DT-1 RCN Model Correlation
DT-1 RCN
EASY5
12
Common Modeling System

• Rocketdyne
• Received and integrated Rocketdynes EASY5 model
  into CBC EASY5 model
• Controls Group

13
New Components

• Found in New EASY5 Library
• AD (accumulator with an inlet and outlet), Qin,
  Qout for both fluid and gas, EFX heat flux
• PI - Pipe with heat flux
• VO - Volumes with heat flux

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New Accumulator
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EASY5 New Components

• New Parameters EFX and QIN
• EFX defines additional energy flux into the
  volume wall. EFX units are BTUH/in2.
• QIN defines additional heat generated internally
  within the fluid. QIN units are BTUH

16
Conclusions

• EASY5
• Test correlation
• Design tool, test transient conditions
• Common modeling system
• New parts specified
• Recommendation Continue to use EASY5 to model
  hydraulic system

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Modeling Hydraulic Systems Using EASY5

• EASY5 Process
• Building a Model

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EASY5 Process

• Define system and the EASY5 model objective
• Build Model by Placing and Linking the Components
  in the Correct Sequence (use only default or port
  connection method)
• Create an Executable File
• Find an Initial Operating Point (All Time
  Derivatives Zero)
• If the Model Equations Converge, Run a Simulation
• Plot Any Output As a Function of Time

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Building the Model

• Start with simple foundation model, ie, valves
  for actuators, volumes instead of accumulators,
  no tabular functions, average values
• Run to see if results make sense, check with
  other team members (in the ball park values)
• Build on model, make more complex if preliminary
  model checks out
• Make thermodynamic model as simple as reasonably
  possible because of potentially large simulation
  times

20
Actuators Approximated byMetering Valves
Similar to Breadboard Development Test set-up
21
Model of TVC Actuator
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