A Rapid Method for Modeling a Variable Cycle Engine

Summary

Here, we present a protocol to build a component-level mathematical model for a variable cycle engine.

Abstract

The variable cycle engines (VCE) that combine the advantages of turbofan and turbojet engines, are widely considered to be the next generation aircraft engines. However, developing VCE requires high costs. Thus, it is essential to build a mathematical model when developing an aircraft engine, which may avoid a large number of real tests and reduce the cost dramatically. Modeling is also crucial in control law development. In this article, based on a graphical simulation environment, a rapid method for modeling a double bypass variable cycle engine using object-oriented modeling technology and modular hierarchical architecture is described. Firstly, the mathematical model of each component is built based on the thermodynamic calculation. Then, a hierarchical engine model is built via the combination of each component mathematical model and the N-R solver module. Finally, the static and dynamic simulations are carried out in the model and the simulation results prove the effectiveness of the modeling method. The VCE model built through this method has the advantages of clear structure and real-time observation.

Introduction

Modern aircraft demands bring great challenges to the propulsion system, which need more intelligent, more efficient or even more versatile aircraft engines¹. Future military propulsion systems also require both higher thrust at high speed and lower specific fuel consumption at low speed^1,2,3,4. In order to meet the technical requirements of future flight missions, General Electric (GE) put forward the variable cycle engine (VCE) concept in 1955⁵. A VCE is an aircraft engine that can perform di....

Protocol

1. Preparation before modeling

1. Obtain design point performance.
   1. Open Gasturb 13. Select Variable Cycle Engine.
   2. Click on Basic Thermodynamics. Select Cycle Design. Open DemoVarCyc.CVC.
   3. Obtain the engine design point performance. These are shown on the right side of the window.
2. Obtain component maps.
   1. Open Gasturb 13. Select Variable Cycle Engine.
   2. Click on Off Design. Select Standard Maps. Open DemoVarCyc.CVC.

Results

In order to prove the validity of the simulation model, several typical performance parameters selected in static and dynamic simulations are compared with the data in Gasturb.

In a static simulation, we compare several key performance parameters of the model with these parameters in Gasturb to verify the accuracy of the static model. Table 2 shows the result of the comparison at the design point with H=0 m, M_a=0, W_f=0.79334 kg/s under a double bypass ope.......

Discussion

Based on a graphical simulation environment, a VCE component-level model can be built rapidly through modular hierarchical architecture and object-oriented modeling technology. It offers a friendly interface to users and it is convenient to analyze and design the model¹⁹.

The main limitation of this method is the execution efficiency of the model. Because the model is written in scripting language, the model needs to be recompiled every time it runs. Thus, the execution.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Gasturb	GasTurb GmbH	Gasturb 13
MATLAB	MathWorks	R2017b
TMATS	NASA	1.2.0