Influence of aerodynamic lift and centre of pressure position on motorcycle stability.
Loading...
Date
2024
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad de Concepción
Abstract
Las últimas tres décadas han visto un rápido desarrollo tecnológico en las carreras de motocicletas. Actualmente la tendencia está en incluir alas invertidas que generan carga aerodinámica para mejorar la aceleración en la salida de las curvas, junto con otros dispositivos para redireccionar los flujos de aire. Varios autores han estudiado el flujo de aire en las motocicletas modernas, así como la influencia del arrastre aerodinámico en la estabilidad. Sin embargo, falta un análisis en la literatura sobre el efecto de los nuevos componentes aerodinámicos en la estabilidad de la motocicleta. Además, los análisis de estabilidad se han centrado principalmente en condiciones de línea recta, lo que ignora el comportamiento en curva.
En vista de lo anterior, el objetivo de esta investigación es estudiar la influencia del coeficiente de sustentación (Cl) y la posición del centro de presión (CoP) en la estabilidad de la motocicleta para condiciones en linea recta y curvas constantes. Para este fin, mejoramos un modelo en línea recta para considerar carga aerodinámica y desarrollamos un modelo de estabilidad para curvas constantes. Por lo tanto, formulamos las ecuaciones del movimiento guiados por varios diagramas y el modelo fue linealizado utilizando el método de series de Taylor. Posteriormente, estos modelos fueron verificados siguiendo una metodología estandarizada. Para el análisis, se consideran múltiples Cl y CoP posicionados delante, alineados y detrás del centro de masa (CoM) de la motocicleta. Con esto, los resultados muestran que incluir carga aerodinámica disminuye la estabilidad del modo weave, mientras aumenta la estabilidad de wobble en recta y en curva. De igual forma, se encontró un efecto estabilizador de la posición del CoP si este se posiciona delante del CoM. Por el contrario, el CoP detrás del CoM empeora la estabilidad de ambos modos de vibrar, principalmente del modo weave. Además, debido a la coherencia obtenida en la verificación y los resultados similares obtenidos para los casos estudiados, se asume que los dos modelos funcionan correctamente. Finalmente, los resultados sirven como un aporte al entendimiento de la aerodinámica y la estabilidad de la motocicleta.
The last three decades have seen a rapid technology development in motorcycle racing. Currently the trend is set in including inverted wings that generate downforce to enhance acceleration on corner exits, along with other airflow-directional devices. Several authors have studied the airflow on modern motorcycles, as well as aerodynamic drag influence on stability, however, there is a lack of evidence in the literature about the effect of downforce on motorcycle stability. Moreover, stability analyses have focused mainly on straight-running conditions, which ignore the behaviour of the system in cornering conditions. In view of this, the aim of this research is to study the influence of lift coefficient (Cl) and Centre of Pressure (CoP) position on motorcycle stability for straight-running and steady cornering conditions. To this end, we upgraded a straight-running model to consider downforce and developed a stability model for steady cornering conditions. To accomplish this, we formulate the equations of motion guided by several diagrams and then the model was linearised using Taylor’s series method. Later, these models were verified following a standard methodology. For the analysis, we consider several Cl and CoP ahead, aligned and behind the motorcycle Centre of Mass (CoM). Results show that including aerodynamic lift decreases weave stability while increasing wobble stability in straight-running and steady cornering. In the same way, we found a stabilising effect from the CoP position if it is located ahead of the CoM. On the contrary, the CoP behind the CoM worsens stability in both modes, mainly in the weave mode. In addition, due to the consistency obtained in the verification, we assume that the two models work properly. Finally, these results contribute to the understanding of motorcycle aerodynamics and stability.
The last three decades have seen a rapid technology development in motorcycle racing. Currently the trend is set in including inverted wings that generate downforce to enhance acceleration on corner exits, along with other airflow-directional devices. Several authors have studied the airflow on modern motorcycles, as well as aerodynamic drag influence on stability, however, there is a lack of evidence in the literature about the effect of downforce on motorcycle stability. Moreover, stability analyses have focused mainly on straight-running conditions, which ignore the behaviour of the system in cornering conditions. In view of this, the aim of this research is to study the influence of lift coefficient (Cl) and Centre of Pressure (CoP) position on motorcycle stability for straight-running and steady cornering conditions. To this end, we upgraded a straight-running model to consider downforce and developed a stability model for steady cornering conditions. To accomplish this, we formulate the equations of motion guided by several diagrams and then the model was linearised using Taylor’s series method. Later, these models were verified following a standard methodology. For the analysis, we consider several Cl and CoP ahead, aligned and behind the motorcycle Centre of Mass (CoM). Results show that including aerodynamic lift decreases weave stability while increasing wobble stability in straight-running and steady cornering. In the same way, we found a stabilising effect from the CoP position if it is located ahead of the CoM. On the contrary, the CoP behind the CoM worsens stability in both modes, mainly in the weave mode. In addition, due to the consistency obtained in the verification, we assume that the two models work properly. Finally, these results contribute to the understanding of motorcycle aerodynamics and stability.
Description
Tesis presentada para optar al grado de Magíster en Ingeniería Mecánica
Keywords
Estabilidad, Aerodinámica, Motocicletas