WS1-1 ADM703, Workshop 1, August 2005 Copyright 2005 MSC.Software Corporation WORKSHOP 1 JET ENGINE...

WS1-1ADM703, Workshop 1, August 2005Copyright 2005 MSC.Software Corporation

WORKSHOP 1

JET ENGINE TURBINE


WORKSHOP 1 – JET ENGINE TURBINE

Problem Statement Use the DEACTIVATE command to model the breaking of one of

the turbine blades off the turbine shaft during engine operation. Examine how the shaft-bearing loads increase after the break point. Compare the difference in results between models with flexible and rigid shafts using the BEAM elements.

Model Description The model contains a rigid shaft part connected to several blade

parts (using fixed joints). The shaft is borne by two bearings (bushings at each end) and driven by a motion.


WORKSHOP 1 – JET ENGINE TURBINE (CONT.)

Simulating the baseline balanced case

1. Start ADAMS/View and import the file, ../adv_modeling/turbine/turbine_shaft.cmd from the training files provided.

2. In the Main toolbox, run a 4-second, 2000-step simulation.

3. Open ADAMS/PostProcessor and plot the shaft cm_angular_velocity (z component) versus time.

It should step from 0 to 30,000 deg/sec.

(Shown on next page)



Simulating the baseline balanced case (Cont.)4. Plot the force magnitudes in the fore and aft bearings versus time.


Simulating the baseline balanced case (Cont.)

5. What are the load magnitudes of the radial and thrust bearings at steady state?_______________________________________________________

Creating the simulation script to break the turbine blade Here, you create and run a simulation script that does the following:

Finds static equilibrium.

Simulates for 3 seconds and 1500 steps.

Breaks off the part blade_1.

Simulates again for one second and 500 steps.



To create the simulation script

1. From the Simulate menu, point to Simulation Script, and then select New.

2. Set Script Type to ADAMS/Solver Commands.

3. From the Append ACF Command pull-down menu, select Static Calculation.

The Commands text box updates.

4. From the pull-down men, select Dynamic Simulation.

The Dynamic Simulation dialog box appears.

5. Set Number of Steps to 1500.

6. Set End Time to 3.

7. Select OK.

8. From the pull-down menu, select Deactivate.

The Deactivate dialog box appears.



To create the simulation script (Cont.)

9. Right-click Joint Name, and point to Joint, point to Guesses, and then select fix_b1.


This is the fixed joint that connects blade_1 to the shaft.

10. Select OK.

11. From the pull-down menu, select Dynamic Simulation.

12. Set Number of Steps to 500.

13. Set End Time to 4.

14. Select OK

15. Select OK again to create the simulation script.


To simulate the model:

1. From the Simulate menu, select Scripted Controls.

2. Select the simulation script you just created (this should be SIM_SCRIPT_2 unless you specified another name).

3. Select the Play button to start the simulation.

Saving and postprocessing Next, save and postprocess the results of your simulation.

To save and postprocess the results:

1. Save the simulated results as turbine_rigid.



To save and postprocess the results (Cont.):

2. As you did earlier, postprocess the results as follows:

Plot the angular velocity of the shaft versus time.

Plot the bearing load magnitudes versus time.

Create a split screen view and animate the model in one window and plot the bearing loads in the other.

Tip: To add the new simulation results to existing plots, select

File Replace Simulation:



To save and postprocess the results (Cont.):

3. What are the load magnitudes of the fore and aft bearings in steady state after the blade break?

____________________________________________________________

4. Why does the load increase and oscillate after the blade break?

____________________________________________________________

____________________________________________________________




Replacing the rigid shaft with a flexible representation First, you import the command file for the altered turbine model, then you

build the discrete flexible links.

To replace the rigid shaft with a flexible representation:

1. Import the file, turbine_shaft_addflex.cmd.

This contains the same model, except that three rigid unconnected parts now represent the turbine shaft: shaft_end_aft, shaft_end_fore, and shaft.

The goal is to build two discrete flexible links: one that connects shaft_end_fore to shaft, and another that connects shaft_end_aft to shaft.



To replace the rigid shaft with a flexible representation (Cont.):

1. (Cont.) To help you create the discrete flexible links, we’ve provided the following markers:

shaft_end_fore.beam_mar: Centered on the inside of the fore shaft-end part.

shaft_end_aft.beam_mar: Centered on the inside of the aft shaft-end part.

beam_mar_aft and beam_mar_fore: Centered on both ends of the middle shaft.

Tip: To see the markers, toggle icon visibility using v.

2. From the Build menu, point to Flexible Bodies, and then select Discrete Flexible Link.

3. Build a discrete flexible link between each of the end parts and the main shaft part (that is, the original one that is now one-inch long and centered in the middle of the rotation axis). Complete the dialog box as shown on the next page.




3. (Cont.)




4. From the Edit menu, select Rename. Rename the model turbine_shaft_flex.

5. From the File menu, select Export. Save this model as a separate command file called turbine_shaft_flex.cmd.

Simulating the enhanced model:

1. Run the same simulation script used in the previous simulation on page .

2. Save the results as turbine_flex.

3. Postprocess the results from the new model and compare the bearing loads with those from the previous simulation.

The plot should look as follows on the next page:



Simulating the enhanced model (Cont.):

3. (Cont.)



Simulating the enhanced model (Cont.):

4. What are the load magnitudes of the fore and aft bearings in steady state after the blade break in the model with the flexible shaft?

________________________________________________________________________________________________________________________

5. Why are the steady-state bearing loads after the blade break higher in the model with the flexible shaft?

________________________________________________________________________________________________________________________

6. Can you deactivate a bushing using an ADAMS/Solver command? Can you modify it?

________________________________________________________________________________________________________________________

WS1-1 ADM703, Workshop 1, August 2005 Copyright 2005 MSC.Software Corporation WORKSHOP 1 JET ENGINE...

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Transcript of WS1-1 ADM703, Workshop 1, August 2005 Copyright 2005 MSC.Software Corporation WORKSHOP 1 JET ENGINE...