1,721,006 research outputs found
Car stability controlled by fuzzy algorithm
Full text linkThis paper introduces an improved Electronic Stability Program for cars that can deal with the sudden burst of a tyre. The Improved Electronic Stability Program (IESP) is based on a fuzzy logic algorithm. The IESP collects data from the same sensors of a standard ESP and acts on brakes/throttle with the same actuators. The IESP reads the driver steering angle and the dynamic condition of the car and selectively acts on throttle and brakes in order to put the car on the required direction even during a tyre burst
Aircraft diesel engine turbocompound optimized
No full textIn order to optimize the design of the thermodynamic cycle of a turbine (Brayton cycle) for using modern common rail as an "active" combustion chamber it was intended to write the present paper. About the present case, the "active" combustion chamber produces a large amount of the mechanical energy that drives the fan. The incoming air is compressed by the compressor, then it is refrigerated and inputted in the diesel engine. A high pressure common rail system optimizes the combustion in the diesel combustion chamber and the expansion begins inside the diesel engine. At the exhaust of the combustion chamber a turbine completes the expansion of the hot gases. A nozzle accelerates the exhaust from the turbine to increase the overall thrust. The mechanical energy from the diesel and from the turbine powers the compressor and the fan. The system can be seen as a turbocharged diesel engine with the turbocharger that outputs energy to the turbofan, increasing the output power and or the efficiency. A diesel-turbine compound can be realized in this way. The coupling of the two systems may be obtained in several different ways. The simplest is to put on the same shaft the compressor, the diesel crankshaft and the turbine. In front of the compressor a speed reducer drives the fan. A second example is to connect the turbine and the diesel on to electric generators. Electric engines are connected to the compressor and to the fan. The traditional turbodiesel has the compressor coupled to the turbine, and the diesel engine that moves the fan. In this latter case, however, the turbine does not energize the fan. Many other hybrid and nonhybrid solutions are possible. The problem is to optimize temperatures, pressures and rpm to the different machines that form the compound. The availability of many experimental data for diesel and turbines makes it possible to obtain a design of a "true" feasible optimum Diesel-Brayton cycle. This efficiency figure justifies the huge manufacturing and development costs of these turbocompound engines [1-4]
Apparato per la propulsione di aeromobili elettrici o termo-elettrici comprendente un sistema di sicurezza e di aggancio, di un pacco batterie, di un motore elettrico e di un dispositivo di spinta raggruppati in un pod.
No full textL’ apparato riguarda la realizzazione di un sistema di propulsione per aeromobili realizzato all’interno di un baccello o pod. In particolare, il sistema di propulsione per aeromobili è composto preferibilmente, ma non limitatamente da un motore elettrico, dotato preferibilmente, ma non esclusivamente da un azionamento. Inoltre il detto apparato propulsivo include un powerpack (pacco batterie), posizionato preferibilmente, ma non esclusivamente, nella parte posteriore. Il powerpack comprende il sistema di gestione delle batterie e di adeguamento della tensione. L’azionamento consente di gestire la potenza in uscita in termini di numero di giri e coppia e di interfacciarsi con il sistema di comando. Il sistema comprende inoltre un sistema di distribuzione e di ricezione dell’energia elettrica con la cellula. Inoltre l’apparato comprende un sistema di contenimento e protezione da esplosioni e incendi dotato di carenature di protezione, paratie e fori di uscita dei fumi . L’appartato è dotato di un sistema di aggancio al velivolo, in cui passano anche gli eventuali cavi per il controllo ed il monitoraggio dell’apparato. Esso inoltre è dotato di un dispositivo di spinta (elica o fan). L’azionamento viene controllato dal pilota o dall’autopilota e fornisce la potenza elettrica al motore elettrico che la trasforma in energia meccanica all’albero dell’elica. L’energia viene prelevata dalle batterie power-pack tramite le schede di controllo del power-pack stesso. Un dispositivo consente la sostituzione rapida del pacco batterie come unico gruppo anche a bordo pista. La ricarica del pacco batterie può anche essere endogena (da parte di dispositivi all’interno del velivolo) o esogena (da parte di dispositivi all’esterno del velivolo)
Apparato per l’installazione ridondante di una cinghia per la trasmissione del moto dell’elica su di un motore aeronautico.
No full textApparato per un sistema di trasmissione a cinghia per velivoli composto preferibilmente, ma non limitatamente da una cinghia dentata, che trasmette il moto a una puleggia collegata all’elica o al fan (ventola). Un perno, sostiene, tramite accoppiamento rotoidale completo, la puleggia elica. Tale perno è fissato, tramite bulloni ad una piastra che funge da puntone. Tale piastra è fissata, sempre tramite bulloni, al basamento del motore. La piastra contrasta il tensionamento della cinghia. Almeno due tiranti (in questo particolare caso tre tiranti), consentono di rendere iperstatica la struttura. In questa particolare esecuzione, a titolo esemplificativo e non esclusivo, uno dei tiranti è fissato al perno puleggia elica, mentre gli altri due tiranti sono fissati direttamente alla piastra. Un tirante dei tre installati (3,4 e 5) consentirebbe il montaggio isostatico dell’assieme. Tuttavia, in questo particolare caso citato a titolo esemplificativo, per motivi resistenziali è necessario installarne almeno due. Il terzo viene montato per ridondanza. Due tiranti consentono il corretto funzionamento della trasmissione anche in presenza dei massimi squilibri ammissibili per i gruppi pulegge e per il dispositivo di spinta, in questo caso, a titolo esemplificativo, un’elica
Structural composites for aircraft design
Full text linkComposite structures such as CFRP offer significant weight reduction over the conventional aluminum alloys for
aircraft. Weight reduction improves fuel efficiency of the aircraft by approximately 20% which results in cost savings and
simultaneously reduces the operational environmental footprint. However, the new aluminum-lithium alloys offer
significant improvements and are viable alternatives to CFRP. Aluminum lithium alloy 2195 with Friction Stir Welding is
introduced as a successful alternative to CFRP primary structures. A "thick skin" monocoque design with integral stringers
as crack stoppers is discussed. An old Macchi 205 WWII fighter plane has been redesigned both in CFRP and 2195-FSW
for comparison. The final designs are comparable in weight, but 2195-FSW is more competitive based on mass production
costs, reparability, and environmental impact. Macchi 205 airplane is used due to in-depth experience with the original
aircraft geometry and loads. Knowledge gained here can be directly transferred to larger structures, from corporate jets to
large transport category airplane
High altitude operations with piston engines powerplant design optimization part IV: Radiators optimum design
No full textIn high altitude operations, the cooling system takes part to the vehicle design optimization process. An integrated design of the cooling ducts is strictly necessary. At high altitudes, the cooling air is taken from high-pressure areas into an alternate, extremely optimized, path. A diffuser reduces the airspeed and increases pressure of the cooling air. Then a group of high performance finned radiators rejects the heat from coolant, air charge and oil. The high altitude, after diffuser radiator performance is discussed in this paper. At first high performance Formula 1 radiators are introduced and discussed. Experimental data are also exposed and summarized. The pressure drop and heat rejection are expressed in function or Re and Pr numbers of cooling air. Then the radiator performance at high altitude is extrapolated from the ground test data. Finally a few suggestions on radiator and cooling ducts arrangement are introduced
FEM analysis for critical components in engines systems
Full text linkThis paper introduces a method to simplify a nonlinear problem in order to use linear finite element analysis. This approach improves calculation time by two orders of magnitude. It is then possible to optimize the geometry of the components even without supercomputers. In this paper the method is applied to a very critical component: the aluminium alloy piston of a modern common rail diesel engine. The method consists in the subdivision of the component, in this case the piston, in several volumes, that have approximately a constant temperature. These volumes are then assembled through congruence constraints. To each volume a proper material is then assigned. It is assumed that material behaviour depends on average temperature, load magnitude and load gradient. This assumption is valid since temperatures varies slowly when compared to pressure (load). In fact pressures propagate with the speed of sound. The method is validated by direct comparison with nonlinear simulation of the same component, the piston, taken as an example. In general, experimental tests have confirmed the cost-effectiveness of this approac
TBO evaluation of naval and aircraft diesel engines
No full textThis paper demonstrates that the experience from Formula 1 and watercraft racing can be applied directly to assess and improve the aircraft/maritime conversion of automotive commercial engines. A direct comparison of the main parameters that characterizes modern CRDID (Common Rail Direct Injection Diesel) and Formula 1 racing engine demonstrates that the similarities are hidden inside the design criteria. In fact, CRDIDs should output high torque at low rpm (1000-3000rpm) while racing engine should have top torque at 9000-11000 rpm. This fact introduces much shorter strokes in racing engines that reduce inertia loads. Since pressures are higher for CRDIDs the combustion loads are similar. The techniques used to improve the TBO of Formula 1 spark ignition engine and racing watercraft diesel can then be directly applied to naval and aircraft engines where the low-cost requirements are not so stringent as in mass-produced automotive CRDIDs (millions of items). The same technology that prolongs the Formula 1 TBO from a single race to the whole season can then be successfully used in aircraft/naval CRDIDs. A quantitative assessment of the TBO increase is included in this paper for the various systems that compose a CRDID
High altitude operations with piston engines powerplant design optimization
No full textDiesel and spark-ignition piston engines are an ideal choice for long endurance, high altitude operations (10, 000m/33, 000ft) and extremely high altitude operations (20,000m-65,000ft). These systems are more complex than traditional applications that are normally limited to 5, 000-7, 000m (16, 000-23, 000ft). In fact, the air propulsion system (propeller or fan), the air intake, the fuel system, the turbo charging, the exhaust and the cooling system take part to the design optimization process. An integrated design is strictly necessary. Since prop-fan is currently under development, the design should start from the choice between propeller and fan. This choice will influence optimum cruise speed, critical altitude and aircraft design as a whole. The air induction system is extremely important to improve efficiency, endurance and critical altitude. At low altitude, a filtered induction system is used for takeoff. At high altitudes, the intake air is taken from high-pressure areas into an alternate, extremely optimized, path. This induction system recovers as much pressure as possible, air kinetic energy at cruise speed. In propeller systems, the intake is usually positioned in the lower part of the aircraft. On fan systems, a little amount of "high pressure" air is taken from the high-pressure area of the fan. The exhaust system is also critical with the choice between pressure recovery and thrust. Exhaust-pressure-recovery reduces backpressure and temperature at exhaust. However, the improvement in critical altitude is marginal. In more common, thrust driven exhaust systems, the exhaust energy is converted into speed and thrust. At the relatively high speed of high altitude cruise, also the cooling system adds a small amount of thrust through the Meredith's effect. The piston engine power plant design is then extremely critical. Many different components should find the correct position for maximum performance. The power-plants of WWII water-cooled fighters and bombers are good examples, even if their design cruise altitude is below 10, 000m (33, 000ft). Modern turbofan and turbojet air intakes are also of help. However, the requirements of low weight, high reliability and long endurance HALE (High Altitude Long Endurance) UAVs (Unmanned Aerial Vehicle) requires further work on this specific subject
Project of inventive ideas through a TRIZ study applied to the analysis of an innovative urban transport means
No full textOpening from an examination of all the best features of accomplishment of the hoverboard, a modern vehicle for urban transport, we have created inventive ideas to design the transport means itself. Quality Function Deployment methodology has given us the requirements to start from, while the TRIZ methods have provided us the proposals and notions of an innovative landscape to which we tend. In practice, while the QFD methodology has a powerfully conceptual appeal, and it is the basis of our analysis, the TRIZ method gives a more innovative thrust and deals the aspects that are strongly constructive and concrete. The Matrix of Contradictions was used within the Hill Model, and through it, we have been able to rework the innovative problems, suggested by the QFD analysis, in terms of technical contradictions. At the end of the work, a number of suggestions were made to further innovate this urban and modern means of transport: the hoverboard
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