|Tipo di tesi||Tesi di laurea magistrale|
|Titolo||Simulazioni numeriche di film liquidi sottili con trasferimento di calore: applicazione per il raffreddamento dei motori elettrici|
|Titolo in inglese||Numerical simulation of thin liquid film flows with heat transfers: application to electric motors cooling|
|Struttura||Dipartimento di Ingegneria "Enzo Ferrari"|
|Corso di studi||Ingegneria Del Veicolo (D.M.270/04)|
|Data inizio appello||2019-12-02|
|Disponibilità||Embargo di 3 anni|
|Data di rilascio||2022-12-02|
Nell’ambito della gestione termica dei motori elettrici destinati al settore automotive, fra le diverse soluzioni possibili, trova spazio l’iniezione di getti d’olio di raffreddamento diretti sulle parti attive del motore. Tali getti portano alla formazione di film liquidi sottili sugli avvolgimenti dello statore, che vengono quindi raffreddati per convezione.
Among different strategies for the thermal management of automotive electric motors, the oil cooling by direct impingement on motor active parts is one of the most interesting. Oil jests lead to the formation of thin liquid film flowing over the stator’s end windings, which are then cooled down by convection. The present work represents a first approach to the numerical simulation of these thin films by using the volume of fluid (VOF) method for two-phase incompressible flows available in the commercial software CONVERGE. Based on an experimental setup available in literature, laminar flows (Re = 2.6 – 4.9 - 5.8) over a heated inclined plate have been simulated. Film thicknesses and velocity profiles have been calculated and analysed as well as thermal aspects, such as temperature profiles and heat transfer coefficients. Simulations results over hydrodynamics aspects have been validated based on experimental measurements and analytical results. The latter have been derived from Nusselt’s theory. In order to define the proper simulation setup, the influence of a series of numerical and physical parameters have been evaluated and discussed. At first, a mesh convergence study has been made to provide sufficient accuracy along with reasonable CPU-time. Time-steps and cells size aspect ratio impact have been then tested for steady and transient solutions. Furthermore, two different computational domain orientations have been compared, and not negligible differences, still not explained, are reported. The possibility to rely on the adaptive mesh refinement (AMR) has also been evaluated: despite relevant CPU-time saving, slight results differences were observed on both hydrodynamics and thermal aspects. In order to meet the solution accuracy requirements, an optimization on the AMR setup was retained to be necessary. Once a series of numerical parameters have been tested, the best identified compromise in terms of CPU-time and results accuracy was used to evaluate the Reynolds number’s effect on the film behaviour: results met the expectations on film velocity profiles and thicknesses, as well as temperatures and therefore heat transfer coefficients.