A Rapid Method for Modeling a Variable Cycle Engine

This method help researchers to quickly build a model of an aircraft engine with existing engine data. This main advantage of this method is that has no high requirements for the programming technology that have happened for traditional modeling. Before beginning the modeling, open GasTurb13 and click Basic Thermodynamics.

Select Cycle Design and open demo variable cycle. The engine design point performance parameters will be shown. To obtain the component maps, in the main window click Off Design, More, and standard maps.

Open demo variable cycle and select LPC, IPC, HPC, HPT and LPT. To model a single component of a variable cycle engine, open a data analysis program and click Simulink. Double click on blank model and click library to place a function to model.

Double click function. The thermodynamic equation of the compressor will be described according to the working principle of the compressor. Click the equation and paste to obtain the input and output of the compressor.

Rename the function compressor. In the compressor function window, right click on the function name and select subsystem and model reference and create subsystem from selection to mask the module. When all of the components have been modeled, combine the output of each component with the input of the next component.

Here the results of the comparison at the design point under a double bypass operating mode are shown indicating that the maximum error of the performance parameters between the model and the GasTurb is an engine pressure ratio below 2%Here, a result of the comparison at the off design point, under a single bypass operating mode are shown. Under these conditions, the maximum error is a rotational speed of low-pressure shaft just below 4%In this representative acceleration, deceleration simulation processed under a double bypass mode the input of the fuel flow is shown. These rotational speed, air flow, and temperature before the turbine data demonstrate that the model is able to perform an acceleration, deceleration simulation.

In this representative experiment, the variable cycle engine operating mode was switched from the single bypass mode to the double bypass mode at five seconds to prevent the engine from exceeding the limited speed during the switching process, a single variable closed loop control was applied to the rotational speed of the high pressure shaft. In this assay, the rotational speed of the high pressure shaft remained nearly unchanged during the switching. Similarly, the response of the fuel flow, rotational speed, air flow, and temperature before the turbine can be observed.

The acceleration, deceleration, and mode switching simulation results confirm that two dynamic simulation, the model can run correctly. Learning how to select a specific or common working equation's important, because common working equation help to set up the model correctly. Following this procedure, other types of aircraft engines or gas turbine engines models can be built.