The mechanical and economic advantages given by downsizing, together with the improvement of the efficiency of internal combustion engines, has led turbocharging to become widespread in the automotive industry. However, its application and implementation with the engine system need to be investigated. In the last decades, Computational fluid-dynamic have assumed a leading role in the design of turbocharging and in the turbo-matching processes thanks to the possibility of examining different layouts and thermo-fluid dynamic conditions without the prototyping cost of experimental analysis. Nevertheless, CFD modelling have always been a trade-off between high computational cost, to obtain accurate results, and low computational time with the consequent detriment of low accuracy. The current thesis work, that has led to the development of the 3Dcell method for the simulation of turbocharging, seems to be a perfect compromise between these two extremes. 3Dcell is a quasi-3D pseudo-staggered leapfrog method that allows to obtain results in few minutes as for 1D CFD models without losing the three-dimensional flow features. It has been developed by the Internal Combustion Engine (ICE) Group of Politecnico di Milano with the aim of performing acoustic analysis. Now, thanks to this work, it has been adapted and customized for simulating turbochargers. Moreover, the possibility of drawing compressor characteristic maps, crucial for turbocharging analysis, gives potentially a major advantage as these documents are often incomplete or unavailable.
I vantaggi strutturali ed economici dati dal Downsizing, insieme al miglioramento del rendimento dei motori a combustione interna, hanno portato all’ampia diffusione dei turbocompressori nel settore automobilistico. Tuttavia, la loro applicazione e implementazione necessita di accurati studi. Negli ultimi anni, la CFD (fluidodinamica computazionale) ha assunto un ruolo fondamentale nella progettazione e sperimentazione dei turbocompressori grazie alla possibilità che offre nell’analizzare diversi assetti e diverse condizioni termo- fluidodinamiche senza l’onere dei costi sperimentali. Ciononostante, le analisi CFD pongono l’analista a prediligere tra un’alta accuratezza dei risultati, con conseguente allungamento dei tempi di calcolo, e un’elevata velocità di esecuzione a scapito dell’esattezza dell’analisi. Un ottimo compromesso tra queste due scelte è il metodo 3Dcell per la simulazione di turbocompressori, frutto del lavoro di questa tesi. 3Dcell è un metodo staggered leapfrog quasi-3D che permette di effettuare analisi di geometrie tridimensionali con lo stesso tempo di calcolo dei metodi monodimensionali. Progettato dal team di motori a combustione interna del Politecnico di Milano con lo scopo di effettuare analisi acustiche, il codice è stato adattato e esteso per le analisi di turbocompressori. Tra le sue potenzialità, la più importante è scuramente la possibilità che offre nel rappresentare la mappa del compressore. Tale documento è infatti fondamentale, ma spesso incompleto o irreperibile.
Development and application of a quasi-3D model for the simulation of turbochargers for internal combustion engines
BORSELLINO, LIBORIO
2017/2018
Abstract
The mechanical and economic advantages given by downsizing, together with the improvement of the efficiency of internal combustion engines, has led turbocharging to become widespread in the automotive industry. However, its application and implementation with the engine system need to be investigated. In the last decades, Computational fluid-dynamic have assumed a leading role in the design of turbocharging and in the turbo-matching processes thanks to the possibility of examining different layouts and thermo-fluid dynamic conditions without the prototyping cost of experimental analysis. Nevertheless, CFD modelling have always been a trade-off between high computational cost, to obtain accurate results, and low computational time with the consequent detriment of low accuracy. The current thesis work, that has led to the development of the 3Dcell method for the simulation of turbocharging, seems to be a perfect compromise between these two extremes. 3Dcell is a quasi-3D pseudo-staggered leapfrog method that allows to obtain results in few minutes as for 1D CFD models without losing the three-dimensional flow features. It has been developed by the Internal Combustion Engine (ICE) Group of Politecnico di Milano with the aim of performing acoustic analysis. Now, thanks to this work, it has been adapted and customized for simulating turbochargers. Moreover, the possibility of drawing compressor characteristic maps, crucial for turbocharging analysis, gives potentially a major advantage as these documents are often incomplete or unavailable.File | Dimensione | Formato | |
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2017_18_BORSELLINO_LIBORIO.pdf
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Descrizione: Development and application of a quasi-3D model for the simulation of turbochargers for internal combustion engines
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https://hdl.handle.net/10589/141523