TurboJet🔗
A jet engine is a type of reaction engine discharging a fast-moving jet that generates thrust by jet propulsion. It is well known, especially from the various types of aircraft. The definition is quite broad since it can include rockets, water jets, and hybrid propulsion. The term jet engine typically refers to an air-breathing jet engine such as a turbojet, turbofan, ramjet, or pulse jet. In general, jet engines are combustion engines.
Preparation🔗
The turbojet model requires to have Modelon Impact Pro version installed, which includes all Modelon libraries. Two libraries: Jet Propulsion and Electrification libraries will be used in this workshop.
Simple Model🔗
The model that will be built resembles the GE J85. The model will be steady-state, including one design point.
Different Conditions🔗
This chapter will show how to set up and run off-design models at different operating conditions.
Bleed flows🔗
We will now add bleed flows to the J85 model. These bleed flow are streams of compressed air extracted from a compressor. There are many reasons for extracting bleed flows. The most important ones include the need for cooling flows for the hottest sections of the turbine, the improvement of compressor surge margin, and the provision of compressed air for other purposes onboard the aircraft such as air conditioning or anti-icing. Here, we will consider turbine cooling flows and customer bleed flows.
Electrification🔗
The major part of the tutorial above focused on Steady State modeling, but in this section we will show how to transition into a dynamic model. We make use of the components from the Electrification Library.
Enhanced Turbojet Multi-point🔗
Classic cycle design relies on an on-design simulation at the design point. Afterward, the performance of the gas turbine can be computed on many other operating points using off-design simulation. However, the sequential process of defining the design parameters, computing performance on key operating points and going back to change the design parameters until all goals are met can be tedious. For complex cycles, it is also not always obvious how to change design parameters to satisfy potentially conflicting goals. Multi-point design, therefore allows a user to concurrently include an on-design model and several off-design models in a single experiment. The models are interconnected to use consistent sizing information, and design rules as well as control laws can be used to couple them.
Preparation🔗
We recommend structuring multi-point models in a specific way.
- The baseline model is stored with the name Baseline. It contains the physical component model instances such as the compressor and turbine without any controls.
- The controlled single-point model is saved with the name Controlled. It extends from the baseline model and adds controls and aggregation components.
- The single-point model prepared for use as a sub-model in the multi-point setup is called SubModel. It also extends from the baseline model and adds inputs and outputs to feed data from the multi-point level.
- Different multi-point setups are stored in sub-packages with meaningful names.
Sub-model🔗
Previously, you ran on- and off-design simulations with the controlled model. We will now create a single-point model variant that is controlled externally, and can thus be included in the multi-point setup later on.
Multi-point Model🔗
We will now create the multi-point model. This has two main steps. First, we automatically create a draft model with the sizing link between on-design and off-design points. This draft is then edited manually to complete the multi-point setup.
Simulation🔗
All models were set up now and we can start simulating the multi-point problem.