IV EELV A Thermal Hydraulic Model for Expendable Launch Vehicles Michael Berglund Delta IV Launch Vehicle Development May 16-17, 2000

Created by Michael Berglund 1

IV EELV 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

Created by Michael Berglund 2

IV EELV 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%) Created by Michael Berglund 3

IV EELV 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%) Created by Michael Berglund 4

IV EELV Fluid Temp Rise Across Orifice TVC1, 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

Created by Michael Berglund 5

IV EELV Fluid Temperature Rise In Flight

Created by Michael Berglund 6

IV EELV 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) 7 Created by Michael Berglund

IV EELV EASY5 DT-1 RCN Model

Created by Michael Berglund 8

IV EELV RCN Velocity and Stroke Stroke & Velocity vs. Time

-5.0

-10.0

-15.0

-20.0

0.0

20.0

15.0

10.0

5.0

0.0

Velocity Transducer LVDT-in.

Calculated LVDT 0.5

1.0

Time (sec)

1.5

DT-1 RCN 2.0

2.5

Created by Michael Berglund EASY5 9

IV EELV Force Data

3000 2000 1000 0 -1000 -2000 -3000 0.0

0.5

1.0

Time (sec)

1.5

DT-1 RCN Force 2.0

2.5

Created by Michael Berglund EASY5 10

IV EELV DT-1 RCN & Model Correlation

10.00

5.00

0.00

-5.00

-10.00

0.0

Force Data

3000 2000 1000 0 -1000 -2000 -3000 0.0

Force 0.5

1.0

Time (se c)

1.5

2.0

2.5

Spring Characteristics of Air Spring

3000 2000 1000 0 -1000 -2000 -3000 -6.0

-5.0

-4.0

-3.0

-2.0

-1.0

0.0

Stroke (in)

1.0

2.0

3.0

4.0

5.0

Stroke vs. Time

0.5

1.0

Time (se c)

1.5

2.0

LVDT-in.

2.5

DT-1 RCN Created by Michael Berglund EASY5 11

IV EELV Common Modeling System



Rocketdyne



Received and integrated Rocketdyne’s EASY5 model into CBC EASY5 model



Controls Group

Created by Michael Berglund 12

IV EELV 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

13 Created by Michael Berglund

IV EELV New Accumulator

Created by Michael Berglund 14

IV EELV 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

Created by Michael Berglund 15

IV EELV Conclusions



EASY5



Test correlation



Design tool, test transient conditions



Common modeling system



New parts specified



Recommendation: Continue to use EASY5 to model hydraulic system

Created by Michael Berglund 16

IV EELV Modeling Hydraulic Systems Using EASY5



EASY5 Process



Building a Model

17 Created by Michael Berglund

IV EELV 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

Created by Michael Berglund 18

IV EELV 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

19 Created by Michael Berglund

IV EELV Actuators Approximated by Metering Valves

Similar to Breadboard Development Test set-up 20 Created by Michael Berglund

IV EELV Model of TVC Actuator

Created by Michael Berglund 21

IV EELV

Created by Michael Berglund 22

IV EELV

Created by Michael Berglund 23

IV EELV

Created by Michael Berglund 24