Chapter 4
Results of analysis
A MathCAD program created to carry out the new rotor analysis consisted of an input parameters section and an equations/results section. In the equations/results section, the program performed the analysis according to the following steps: a) Air and diffuser b) Compressor c) Burner d) Turbine e) Overall APU properties The turbine portion evaluates only the subsonic flow if the supersonic region does not occur. Before continuing with the rotor analysis, it was important to validate the burner and turbine equations by comparing them with simple flow problems. The purpose was to provide confidence in the usage of the burner and turbine equations.
4.1
Simple one-dimensional flow A simple flow involves no curvature (β does not change) and rotation along with constant
specific heats. For convenience, the equations in this section will use relative frame variables (absolute and relative frames are the same for simple flows). Simple cases for the burner are: a) Flow in a constant area duct with drag and heat addition. b) Flow in a constant area duct with only heat addition. For both cases above, mf is extremely small compared to m3. As for the turbine, the chosen simple case is the variable area duct flow.
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