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rfenrich / F100-nozzle

Collection of MATLAB scripts and functions for simulating the behavior of the F100-PW-220 turbofan engine and an attached nozzle.
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3-spline nonideal nozzle case solved incorrectly by ode45 #2

Closed rfenrich closed 9 years ago

rfenrich commented 9 years ago

Using mission 3 for the standard 3-spline nozzle in driveNozzle.m gives an incorrect solution for the non-ideal nozzle, where flow remains subsonic throughout the nozzle instead of passing Mach 1 and becoming supersonic in the aft portion of the nozzle. The issue can be fixed by entering the nozzleNonIdeal.m function and changing the initial condition for the 4th order Runge-Kutta integration of the aft portion of the nozzle from 1.005 to 1.01. This effectively starts the integration on the "right footing." However a more accurate and robust solution is desired.

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rfenrich commented 9 years ago

Potentially fixed with new implementation of integrating through transonic region at throat (slope of Mach (dM/dx) is fixed at throat with a scaling constant based on analytical equation from physics). This should enable more consistent integration between cases. However, now it appears there is a problem with the spline geometry calculations for the ideal nozzle that has arisen because of this.

rfenrich commented 9 years ago

Issue is deemed fixed with new method of integration through the throat region.