Ellipse Law
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![Stodola's cone for a turbine not choked.](/Images/godic/202501/11/Stodola's_cone_not_choked.svg3658.png")
![Stodola's cone for a turbine with the last stage choked.](/Images/godic/202501/11/Stodola's_cone_choked.svg3658.png")
The Law of the Ellipse, or Stodola's cone law, provides a method for calculating the highly nonlinear dependence of extraction pressures with a flow for multistage turbine with high backpressure, when the turbine nozzles are not choked. It is important in turbine off-design calculations.