1. Conventional and Model Based Test analysis
GasTurb 13
Conventional and Model Based Test analysis
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2. For this tutorial we will use a
GasTurb 13 Main Window
For this tutorial we will use a
2 Spool Turboshaft.
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3. Select the engine model
We Need Some Data
Select the engine model
Open the engine model
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4. Test Analysis Input Data Page
Switch Test Analysis on and have a look at the Stations Window if you are not sure about where the measurements are taken.
Then calculate the Design Point.
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5. Test Analysis Result Copyright © GasTurb GmbH
These are the measured data given on the test analysis page…
These are the iteration variables adjusted to meet the measured data…

6. Design Point Input Data Page
What if W2Rstd is not measured and thus not known?
Iterate W2Rstd in such a way that the calculated T5 is equal to the measured T5, for example.
Some input quantities, such as compressor and turbine efficiency, pressure ratio and burner exit temperature, are not visible because these data are results in test analysis mode.
Note that the data on the Test Analysis Input Page are not the only ones affecting the test analysis. All the other cycle input data, including the secondary air system, must be known for a precise result.
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You can find W2Rstd if you have measured data for T45 or T5. If these values are not known then you may know the HP turbine flow capacity W41Rstd.

7. Two Test Analysis Methods
Conventional Test Analysis
Calculates the Cycle Employing the Measured Data
Some Knowledge About the Engine is Required
Secondary Air System
The Test Analysis Runs in Cycle Design Mode
The Test Analysis Result is Difficult to Judge:
Is Compressor Efficiency Poor Because the Compressor is Damaged or Because it Runs at Aerodynamic Overspeed?
Model Based Test Analysis
Compares the Measurements with a Model of the Engine
A Full Thermodynamic Model is the Basis
The Test Analysis Runs in Off-Design Mode
Factors to the Component Performance are Found Which Make the Model Agree With the Measured Data
The Test Analysis Result is the Deviation Between the Model and the Engine
The Result for Compressor Efficiency is Independent of the Operating Point: Better or Worse than Expected
What we have done up to now was a Conventional Test Analysis. Now we go for the Model Based Analysis, also called Analysis by Synthesis (AnSyn)
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8. The file opening menu will appear automatically, read the file
GasTurb 13 Main Window
The file opening menu will appear automatically, read the file
Demo_mgtf.cgm
After reading the data, the cycle design point will be calculated in the background and then the Off-Design Input Window opens.
Now we will use a
Geared Mixed Turbofan
In calculation mode
Off Design
With Standard Maps
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9. Off Design Input Window
Select Test Analysis and switch to the Test Analysis View
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10. Test Data Input Copyright © GasTurb GmbH
Click here to run the test analysis
Example test data are stored in the file.
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11. Click here to see the whole cycle
AnSyn Result
Click here to see the whole cycle
A value of 1 (or 0K respectively) for the AnSyn Factors in this column means perfect line-up of the measurement with the model.
The HPC Efficiency Factor is around 0.982, that means the HPC performs worse than expected.
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12. AnSyn Result Copyright © GasTurb GmbH
Remember:
the overall compression pressure ratio P3/P2 is
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These are the measured data given on the test data page.

13. Correction to Nominal Conditions
Change Delta T from ISA to 0
Click here to run the ISA Correction
Now run the model
- with the AnSyn Factors applied -
at the same corrected spool speed as tested. This yields pressure ratios that are very close to those during the test.
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14. Data Corrected to Nominal Conditions
Now the overall compression pressure ratio P3/P2 is 35,67347
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15. Sensitivity to Measurement Errors
Sensitivity to Measurement Errors can be calculated automatically
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16. Sensitivity to Measurement Errors
Need Explanations?
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17. Flexibility of AnSyn Copyright © GasTurb GmbH
What if no measured mass flow W2 is available?
Here you can choose the
Core Flow Analysis Method.
Define an Iteration
Core Flow Analysis Methods
Iterate Bypass Ratio (Core Flow) in such a way that one of the following conditions is fulfilled:
W41Rstd = given W41Rstd (HP Turbine Capacity)
W45Rstd = given W45Rstd (LP Turbine Capacity)
T45 = Measured T45
T5 = Measured T5
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18. Defining an Iteration Copyright © GasTurb GmbH
Assume that the fan model is correct, for example. That means the Fan Flow Factor is equal to 1
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19. This is now the start value for the iteration.
Calculate…
This is now the start value for the iteration.
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20. Mass Flow W2 Found by Iteration
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21. Conventional and Model Based Test Analysis Tutorial
Flexibility of AnSyn
What if there are additional measured data to be considered ?
… and use optionally an iteration to bring the measurement in line with the Composed Values.
Employ these placeholders for input of the data…
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This slide ends the
Conventional and Model Based Test Analysis Tutorial