燃气轮机计算.pps

燃气轮机计算.ppsME 423Chapter 8PREDICTION OF PERFORMANCE OF SIMPLE GAS TURBINES
Prof. Dr. O. Cahit ERALP
From cycle calculations it is possible to determine the PRESSURE RATIO ( Rc ) which will give the best overall efficiency for a given Tmax.
 
MASS FLOW RATE to give the most suitable desired power output.
  
After such preliminary calculations, the most suitable design data for a particular application can be chosen.
Then, it is possible to design ponents to give the required operation at the design point.
That is running at the design speed N*, mass flow rate m* and pressure ratio R*.
Prediction of Performance of Simple Gas Turbine
Me 423 Spring 2006
Prof. Dr. O. Cahit ERALP
Then the off-design performance has to be determined which is the divergence from the design point over plete operating range of speed and power output.
The performance ¢ of the ponents may be estimated on the basis of the previous experience or actual experiments. When they bined in an engine their operating range is considerably reduced.
The problem is to find the Operating point (OP) on ponent ¢ when the engine is running at a steady speed (EQUILIBRIUM). 
The plot of these OP's form the EQUILIBRIUM RUNNING LINE (ERL).
Prediction of Terformance of Simple Gas Turbine
Me 423 Spring 2006
Prof. Dr. O. Cahit ERALP
For the whole range of operating speeds, it will generate the EQUILIBRIUM RUNNING DIAGRAM.
Determining the OP; the power output, thrust and the SFC can be obtained.
The Equilibrium Running Diagram indicates the margin of operation from the surge line (SL) .
This margin indicates a Margin of stability; indicates if there is enough margin to operate with pressor efficiency.
If the surge line is crossed some action has to be taken to recover, not to give rise to a failure.
Ideally the engine should be operated within the region of maximum possible efficiencies.
Prediction of Performance of Simple Gas Turbine
Me 423 Spring 2006
Prof. Dr. O. Cahit ERALP
Variation of SFC with reducti