A Thermal Hydraulic Model for Expendable Launch Vehicles

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Created byMichael Berglund

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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 DataRocketdyneThermal analysisDT-1 RCN

Point 2 - Design Tool, Test Transient ConditionsPoint 3 - Common Modeling System

RocketdyneControls group

Point 4 - Good Customer SupportNew Parts Specified

Modeling Hydraulic Systems Using EASY5Summary 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 = 76°F Hand Calculations: Oil

temp rise across orifice (same conditions) results:

T = 75.9°F

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Fluid Temperature Rise In Flight

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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

Stroke & Velocity vs. Time

-20.0

-15.0

-10.0

-5.0

0.0

5.0

10.0

15.0

20.0

0.0 0.5 1.0 1.5 2.0 2.5

Time (sec)

Stro

ke-in

, Vel

ocity

-in/s

ec

Velocity Transducer

LVDT-in.

Calculated LVDT

DT-1 RCN EASY5

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Force Data

-3000

-2000

-1000

0

1000

2000

3000

0.0 0.5 1.0 1.5 2.0 2.5Time (sec)

Forc

e (lb

)

Force

DT-1 RCN EASY5

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DT-1 RCN & Model Correlation

Stroke vs. Time

-10.00

-5.00

0.00

5.00

10.00

0.0 0.5 1.0 1.5 2.0 2.5

Time (sec)

Stro

ke-in

, V

elo

city-in

/sec

LVDT-in.

Spring Characteristicsof Air Spring

-3000

-2000

-1000

0

1000

2000

3000

-6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0

Stroke (in)

Fo

rce (lb

s)

Force Data

-3000

-2000

-1000

0

1000

2000

3000

0.0 0.5 1.0 1.5 2.0 2.5Time (sec)

Fo

rc

e (lb

)

Force

DT-1 RCN EASY5

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Common Modeling System

Rocketdyne Received and integrated

Rocketdyne’s EASY5 model into CBC EASY5 model

Controls Group

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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

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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 ProcessBuilding 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

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Actuators Approximated byMetering Valves

Similar to Breadboard Development Testset-up

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Model of TVC Actuator

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A Thermal Hydraulic Model for Expendable Launch Vehicles

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