1,721,164 research outputs found
Metodo per il Progetto Preliminare di Turbomacchine Assiali Basato sulla Teoria del Potenziale
No full textQuesta tesi presenta un metodo di progetto preliminare di turbomacchine assiali fondato su un metodo a potenziale.
Il lavoro si articola su due diversi aspetti del problema, dapprima la costruzione di un modello teorico capace di simulare il campo di moto fluido in una turbomacchina, quindi la determinazione di una serie di relazioni tra parametri analitici e grandezze fisiche che permettano di applicare il modello alla progettazione.
L’approccio è non viscoso, irrotazionale e bidimensionale, quindi studia separatamente le superficie meridiane ed interpalari, i cui campi di moto sono interconnessi esclusivamente da vincoli di tipo geometrico e di continuità. Il modello riesce quindi a prevedere l’influenza sul deflusso di tutti quegli elementi che la teoria monodimensionale non può contemplare, cioè ripercussioni su velocità e gradienti di pressione dovute alla geometria meridiana, ed effetti sul deflusso interpalare legati a spessore, calettamento, incidenza, curvatura e solidità dei profili palari. La parte successiva dello studio, più strettamente ingegneristica, consente di pervenire al disegno preliminare di una macchina di prestazioni desiderate a partire dalla sola conoscenza dei numeri caratteristici, attraverso la scelta da parte del progettista di opportuni vincoli sulle geometrie possibili. Il lavoro presenta anche alcune applicazioni progettuali a titolo di esempio
Analisi fluidodinamica di testate rotonde per l’estrusione di prodotti alimentari tipo pasta
No full textMeasurement of the effect on brake performance of the intake and exhaust system components in a motorbike high speed racing engine
No full textThe paper presents a series of brake performance measurements for a high speed Road Racing Supersport motorbike engine. A modular approach consisting in a progressive assembling of each component belonging to the intake and exhaust systems is used to investigate the influence of these components on volumetric efficiency through brake torque chassis dynamometer tests. In spite of the design effort that is usually made to keep the cylinder air intake independent of each other in this kind of engines, results showed a considerable acoustic coupling between the intake primary manifolds and the upstream components. Moreover, a good correspondence is found about intake and exhaust tuning regimes between experimental results and analytical relationships proposed in the literature. The presented results can also be interpreted as representative for the overall very high speed engines category (including MotoGP and F1 ones), being the air-breathing system layout mostly independent of engine technological level within this category
Experimental comparison of the brake performance of a spark ignition engine fuelled with gasoline and LPG.
No full textThe use of LPG as alternative fuel to gasoline is common practice in spark ignition internal combustion engines. In the past, the main reason for the use of LPG as fuel was merely due to the lower cost for the final user in comparison with gasoline. However, there are theoretical reasons to consider LPG as a very attractive fuel for internal combustion engines. Nowadays, there is a continuously increasing stock production of dual-fuel (gasoline-LPG) passenger car models. Despite of that, doubts about the real performance worsening in LPG operation still exist. The paper deals with the theoretical advantages of using LPG as fuel for spark ignition internal combustion engines. Brake performance derived from experimental analyses at the test bed of a passenger car engine fed either with gasoline and LPG are analysed and compared. The engine designed to operate with gasoline has been equipped with one of the more recent standard kit for the dual-fuel engine operation. The performance decrease in LPG operation are discussed both in steady state and transient condition
Ricerca sulla ripartizione della portata a valle della biforcazione in una condotta forzata
No full textRapporto per STE-Energy S.p.A., di Padova
Experimental analysis on a spark ignition petrol engine fuelled with LPG (Liquefied Petroleum Gas)
No full textThe use of LPG (liquefied petroleum gas) as alternative fuel to petrol is common practise in spark ignition engines. While the main driving force to the use of LPG still remains the low cost for the end user, its favourable pollutant emissions, in particular carbon dioxide, will in the middle term probably increase interest in LPG as an IC engine fuel. In addition, there are both theoretical and technical reasons to consider LPG as an attractive fuel also in terms of engine performance. Despite the continuously increasing stock production of dual-fuel (petroleLPG) passenger car models, doubts still exist about both real engine performance in LPG operation and the reliability of the dual-fuel feeding system. This paper deals with the theoretical advantages of using LPG as fuel for SI engines. Brake performance tests of a passenger car engine fed with petrol and LPG are analysed and compared. The stock engine has been equipped with a “third-generation” standard kit for dual-fuel operation. The performance reductions in LPG operation are discussed in both steady state and transient condition. The results of some modifications to the set-up of both the petrol and LPG metering devices, designed for a better justification of the measured performance, are also presented
Realizzazione di una nuova serie di giranti per ventilatori industriali a flusso assiale
No full textRapporto per F.lli Ferrari Ventilatori Industriali S.p.A
Measure of the volumetric efficiency and evaporator device performance for a LPG SI engine
No full textThe use of LPG as fuel for spark ignition engines originally designed to be petrol fuelled is common practice in many countries. Despite some theoretical and technical advantages related to LPG fuelling of internal combustion engines, the driving force for the ever-increasing adoption of LPG as fuel for passengers cars still remains its low price. However, money saving for the end-user is falling down year after year enforcing both technical developments and scientific research. Following some previous experimental studies about the real performance of dual-fuel engines during LPG operation, the present paper deals with the two main problems related to LPG port-fuel SI engines: the volumetric efficiency drop and the LPG evaporator device performance. A passengers car SI engine equipped with a “third generation” kit for the dual-fuel operation was tested at the dynamometer. Measures of engine performance, volumetric efficiency and change of LPG thermodynamic states in the evaporator were acquired both in steady state and transient operation of the engine. Experimental data are presented and discussed to evaluate the performance of the dual-fuel engine
CFD modelling to aid the design of steel sheet multistage pumps
No full textMultistage, steel-sheet, centrifugal pumps require shapes that differ from those commonly featured by cast or moulded units. The available literature on pumps design deals mainly with the latter and does not support satisfactorily the hydraulic design of the former. The availability of experimental data is scarce as well. On the other hand, validated CFD models proved to be an effective design tool. The paper deals with the numerical investigation of a vertical multistage pump. It aims at presenting a CFD modelling approach that is computationally low-cost and suited for the early and intermediate steps of hydraulic design of mass production pumps. A single passage of one intermediate stage was modelled by using the Multiple Reference Frame technique and the Arbitrary Matching Interface approach within the open source OpenFOAM ® environment. The influence of the multistage configuration on numerical predictions was accounted analytically. Standard k-epsilon model and wall function approach were used for turbulence closure. This modelling strategy was validated by comparison of the calculated hydraulic performance, efficiency and power consumption with experimental data
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