Projecte llegit
Títol: Bellmouth intake design for test rig airflow adaptation and air mass flow measurement of a micro turbojet
Director/a: MELLIBOVSKY ELSTEIN, FERNANDO PABLO
Departament: FIS
Títol: Bellmouth intake design for test rig airflow adaptation and air mass flow measurement of a micro turbojet
Data inici oferta: 27-07-2020 Data finalització oferta: 27-03-2021
Estudis d'assignació del projecte:
GR ENG SIST AEROESP
| Tipus: Individual | |
| Lloc de realització: EETAC | |
| Paraules clau: | |
| Micro Jet Engine, Air Intake, On-Ground Test Rig | |
| Descripció del contingut i pla d'activitats: | |
| The aim of this project is to review alternative solutions for adapting ther air flow and assessing the air massflow into a micro gas turbine engine in ground testing conditions, and to design a scalable air intake that provides optimal performance and accurate measurements. The work plan will be as follows:
1) literature review on air intakes for gas turbine ground testing 2) design of an optimal intake in terms of flow adaptation 3) simulate air intake performance with open source cfd tools 4) design a system of probe arrays for static and total pressure measurements for air flow evaluation 5) design a data acquisition system to exploit the raw readings from pressure probes 6) Prepare a budget for the construction and assembly of the probe-fitted air intake |
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| Overview (resum en anglès): | |
| A bellmouth intake to adapt the airflow into a micro turbojet (EvoJet170neo) during on ground rig testing has been designed and optimised through numerical simulation with OpenFOAM.
The design that has been chosen for the bellmouth is based on a parametrized elliptical shape that has been generated using CAD tools. Also, 2D axis-symmetrical simulations have been run by taking advantage of the geometry symmetries that are common in a real bellmouth around its axis. The airflow is considered to be incompressible, turbulent and at sea level conditions according to ISA. It has been simulated employing the k-omega SST turbulence model, which implies a careful mesh design. Hence, the mesh has been designed so that in the boundary layers near the walls and inside the intake a structured mesh with quadrilateral cells is maintained, while an unstructured mesh with triangular cells is used in the quiescent atmosphere. Also, a mesh refinement study has been carried out and it has shown that 39 quad cells in wall-normal direction and a thickness below of 0.0265717 m for the first layer of cells away from the walls are needed in order to guarantee that y+ is lower than 2 as required by the turbulence model. The resulting design has guaranteed a good conditioning of the airflow fed into the engine so that the boundary layers remain attached on all walls and that the airflow is homogeneous with deviations way less than 1.8% of the airflow¿s mean velocity. Finally, a rigorous study has been performed to choose the ideal locations for placing total and static pressure probes that give a good estimation of the delivered air mass flow to the engine with numerical background and also an analysis of the correlation with the air mass flow over the full operational range of the engine and how positioning errors of the probes would affect the measurements when installed. In general, it has been demonstrated that we have a good correlation with the air mass flow at these probe positions and that the positioning errors are not really significant. |
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