The aim of the thesis is to develop a method for analyzing an air-to-air missile in supersonic conditions, focusing on the differences between the configuration where only the effect due to the geometry is evaluated (engine-off) and the one where engine effect is added to the rear (engine-on). Analyses were conducted on the NASA Tandem Control Missile (NTCM) model performing both three and two-dimensional simulations for small angles of attack. The engine effect is modeled through an appropriate mass flow. To estimate the mass flow coming from the engine, an iterative method based on the conservation of momentum was developed. Finally, to carry out a more accurate analysis, solution-based method algorithms were implemented to perform grid adaptations in the bidimensional case. In the three-dimensional configuration, given the high computational cost, a shortcut was developed using the cylindrical symmetry. Comparing the results in both the two and three-dimensional cases, we obtained that the polar curves are similar in the engine-on and engine-off configurations. These results are due to the fact that the missile has a streamlined geometry, and in supersonic conditions. The flow separetion generated at the rear does not significantly affect the aerodynamic forces on the whole geometry.
L’obbiettivo di questa tesi è quello di sviluppare un metodo numerico per studiare i missili aria-aria in condizioni supersoniche, focalizzandoci sulle differenze presenti tra due configurazioni. La prima nella quale è considerata solo la geometria (engine-off) e la seconda nella quale sono investigati anche gli effetti dovuti al flusso di massa provenienti del motore (engine-on). Le analisi sono state condotte sul modello NTCM (NASA Tandem Control Missile) sviluppato dalla NASA [4], svolgendo studi sia bidimensionali che tridimensionali per piccoli angoli di attacco. Per simulare l’effetto dovuto al motore è stato utilizzato un metodo iterativo basato sulla conservazione della quantità di moto. Infine, per svolgere analisi più accurate nel caso 2D, sono stati sviluppati due algoritmi di adattazione di griglia basati su “solution-based method”. Per il caso tridimensionale, dato l’elevato costo computazionale, è stato necessario utilizzare un metodo alternativo sfruttando le simmetria cilindrica presente nel problema. Comparando le curve polari ottenute nel caso bidimensionale e tridimensionale è stato riscontrata una sovrapposizione dei risultati tra la configurazione con motore acceso e spento. Questo comportamento è spiegato dal fatto che le simulazioni sono state condotte in condizioni supersoniche e su una geometria di missile affusolata.
Numerical investigation of the effect of the engine mass flow on the NTCM missile using mesh adaptation techniques
Fossati, Lorenzo
2021/2022
Abstract
The aim of the thesis is to develop a method for analyzing an air-to-air missile in supersonic conditions, focusing on the differences between the configuration where only the effect due to the geometry is evaluated (engine-off) and the one where engine effect is added to the rear (engine-on). Analyses were conducted on the NASA Tandem Control Missile (NTCM) model performing both three and two-dimensional simulations for small angles of attack. The engine effect is modeled through an appropriate mass flow. To estimate the mass flow coming from the engine, an iterative method based on the conservation of momentum was developed. Finally, to carry out a more accurate analysis, solution-based method algorithms were implemented to perform grid adaptations in the bidimensional case. In the three-dimensional configuration, given the high computational cost, a shortcut was developed using the cylindrical symmetry. Comparing the results in both the two and three-dimensional cases, we obtained that the polar curves are similar in the engine-on and engine-off configurations. These results are due to the fact that the missile has a streamlined geometry, and in supersonic conditions. The flow separetion generated at the rear does not significantly affect the aerodynamic forces on the whole geometry.File | Dimensione | Formato | |
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https://hdl.handle.net/10589/209412