Download presentation

Presentation is loading. Please wait.

1
**Introduction to Off Design Simulations**

GasTurb 12 – Tutorial 3 Introduction to Off Design Simulations Copyright © Joachim Kurzke

2
**Off-Design Simulations**

Let us begin with a jet engine. Select the most simple engine architecture, a Turbojet. Select as Scope Performance and then click Off Design A click on Standard Maps begins the off-design calculation. Copyright © Joachim Kurzke

3
We Need Some Data… Copyright © Joachim Kurzke

4
**Off-Design Input Data Page**

After reading the file, the cycle design point is calculated. This happens in the background. The standard compressor and turbine maps are scaled in such a way that they fit to the cycle design point. Now we calculate the cycle design point as an off-design point Copyright © Joachim Kurzke

5
**Off-Design Point Summary**

Copyright © Joachim Kurzke The contents of this summary page is identical to that of the cycle design point

6
**Operating Point Details**

This is the Standard High Pressure Compressor Map file Copyright © Joachim Kurzke On this page those details of the operating point are presented that are not needed for a cycle design calculation. This is the Standard High Pressure Turbine Map file

7
**Compressor Map Copyright © Joachim Kurzke**

The circle marks the cycle design point, the yellow square marks the off-design operating point. In this special case – because we have calculated the cycle design point in off-design mode – the yellow square is inside the circle. Copyright © Joachim Kurzke

8
**Turbine Map Copyright © Joachim Kurzke**

The circle marks the cycle design point, the yellow square marks the off-design operating point. There are six different versions of a turbine map. The y-axis can be Pressure Ratio or Corrected Work. Here Turbine Pressure Ratio is shown over the product of Corrected Flow and Corrected Speed. Copyright © Joachim Kurzke

9
**Here Turbine Pressure Ratio is shown over Corrected Speed.**

Turbine Map Here Turbine Pressure Ratio is shown over Corrected Speed. The corrected flow is shown as contour lines in % of the maximum corrected flow in the map Copyright © Joachim Kurzke

10
**Turbine Map Copyright © Joachim Kurzke**

Here Turbine Pressure Ratio is shown with the same axes as a compressor map: Turbine Pressure Ratio over Corrected Mass Flow. The disadvantage of this format is that all the speed lines nearly collapse. Copyright © Joachim Kurzke

11
**Thermodynamic Stations**

Here you get all the details at the thermodynamic stations. The engine geometry - all the flow areas at all stations - is among the results of the cycle design point calculation. Copyright © Joachim Kurzke

12
**Off-Design Input Data Copyright © Joachim Kurzke**

Here you can choose whether Relative Spool Speed ZXN or Burner Exit Temperature ZT4 is given. Enter 2 to make Burner Exit Temperature an input and use 1200 for it Let us run a case with 1200 K Burner Exit Temperature. Copyright © Joachim Kurzke

13
**The solution is found by iteration**

Off-Design Result The solution is found by iteration Copyright © Joachim Kurzke

14
**Compressor operating point for T4=1200K**

Compressor Map Cycle design point Compressor operating point for T4=1200K Copyright © Joachim Kurzke

15
**Now let us calculate the complete sea level static operating line.**

Off-Design Iteration Iteration targets are flow continuity between components and power balances These are the estimated values of the iteration variables. If the iteration fails to converge, you can try with better estimates for the variables. These are the variables of the iteration. Betavalues are auxiliary coordinates in component maps. Now let us calculate the complete sea level static operating line. Copyright © Joachim Kurzke

16
**Off-Design Input Operating Line**

Reset to 1 and enter for the HPC Spool Speed ZXN also 1 Copyright © Joachim Kurzke

17
**Operating Line Input Copyright © Joachim Kurzke**

Increase the Number of Points to 20, then run the case by clicking the Operating Line button The operating line commences with the single point which was calculated before the operating line window was opened. A series of points with decreasing gas generator spool speed will be calculated. The default step size of relative spool speed is Answer No Copyright © Joachim Kurzke

18
**Compressor Operating Line**

We will employ a handling bleed to cure that problem. Here the compressor surges Copyright © Joachim Kurzke

19
**Off-Design Input Operating Line**

Re-run the operating line Click Controls to show the controls button group. Then click the Bleed button Enter numbers in all 3 boxes Copyright © Joachim Kurzke

20
**Repeat the Operating Line Calc**

Answer this time Yes Copyright © Joachim Kurzke

21
**Switch Automatic Bleed “On”**

Enter 1 for the second operating line, then click Run Copyright © Joachim Kurzke

22
**Compressor Operating Lines With and Without Bleed**

Let us have other views on the data Copyright © Joachim Kurzke With bleed the surge problem does not exist.

23
**The Default Plot Copyright © Joachim Kurzke**

With bleed the surge problem does not exist. However, with bleed the fuel consumption is higher… Copyright © Joachim Kurzke

24
New Picture Copyright © Joachim Kurzke

25
New Picture Copyright © Joachim Kurzke

26
**T4 = f(Corrected Spool Speed)**

With bleed the surge problem does not exist; however, the burner exit temperature is significantly higher Copyright © Joachim Kurzke This slide ends the Introduction to Off-Design Simulations Tutorial

Similar presentations

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google