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Mobility is evolving both technologically and socially. We are witnessing a rapid shift to electric mobility, mainly today, with battery. A lack of autonomy and charge time too long are often cited as the main obstacles to the development of electric vehicles. Fuel cell vehicles with hydrogen storage in compressed form at 350 or 700 bars can travel more than 500 km, in a single charge lasting 3 to 5 minutes, they appear more than ever as a credible alternative to current vehicles and complementary to batterie electric vehicules. This article discusses fuel cell technology applied to land transportation by analyzing technological and hydrogen refuelling.
Relative to the performances, the weakest part of a radial inflow turbine is the volute, since half of the total flow losses occur in it. A one-dimensional analysis is developed to define the main flow velocity components entering the rotor. On the same basis, the thermodynamic relations to estimate the performances of the rotor and the whole stage are given, more specifically applicable to turbochargers.
This article is dedicated to centripetal turbines operating with compressible fluids. It details their geometries and the technological adaptations implemented for their operation in applications related to supercharging. After some general information on turbomachines and the history that led to the emergence of centripetal turbines, it describes the various fixed and moving components of centripetal turbines (scroll, variable-pitch blade, partial injection). In addition, all the thermodynamic relationships useful for evaluating their overall performance are presented, followed by the fluid mechanics laws governing the corresponding fluid flows.
This article describes the practical methods used to design piping systems according to the flow conditions of the fluid being transported. Theoretical developments can be found in the article Fluid Mechanics in the treatise Fundamental Sciences. We won't deal here with the flow of non-Newtonian fluids, which is covered in the article Non-Newtonian fluids in the treatise Fundamental Sciences. Further developments can be found in the bibliographical reference .
Aerospace propulsion is based upon models and physical laws which govern the movement and speed of flying systems. This article details the various formulae and laws to be mastered (Bréguet and Tsiolkovski formulae for instance) in order to design a propulsion system efficiently. It provides the way of using estimates, reference levels and simplified design laws for a cruise, an acceleration, a ballistic flight initially propelled. The understanding of these various data facilitates the acquisition of certain calculation "reflexes". In order to gain a sound knowledge of these elements, certain exercises of application (antitank missiles, launcher restitution) are also explained in this article.
Several systems of aerospace propulsion are available and the choice is made according to the desired usage. Engines are classified according to several criteria: technological, functional, or even according to the chemical process of the reaction. This article presents the main type of propulsion systems (turboprops, propellers, ramjets, turbojet and urbofan, pulsed detonation engines, turbo rockets, etc.) as well as certain of their characteristics (type of reaction, area of use, domain of Mach number, etc.). As an example, it more specifically focuses on the choice of propulsion for missiles (anti-missiles, anti-ships, etc.) according to the type of mission carried out.
Aerospace propulsion systems (for aircraft, space launchers, missiles, probes, satellites, etc.) are mostly of two types; reactors and propellers. This article presents several categories of propulsion systems and defines the main quantities used in the domain of the propulsion, such as specific impulse and constructive index. The main industrial trends are also presented.
Several types of space propulsion exist according to the way the propulsive mass is accelerated. Regardless of the chosen method, designing propulsion systems involves several mechanical principles and theories. The dimensioning and production of the propulsion system requires the knowledge and mastery of mathematical and physical tools. This article thus reviews the essential notions of the flight (regime, standard atmosphere, etc.), the aerodynamic and thermodynamic formulae which are used in propulsion in the planning stages, as well as the various level of air and combustion modeling.
This article follows the article Airbreathing engine combustors. Part 1: operation and main physical phenomena and focuses on the numerical simulation of aeronautical combustors. In a first part, several common physical models for reactive gaseous flow (kinetics, turbulence, combustion), the liquid phase (atomisation, evaporation) and radiative transfers will be presented. In each case, the assumptions required to establish these models will be discussed. The ability of these models and methods to deal with practical design problems will then be illustrated on two emblematic examples of decarbonization solutions for aeronautics : the combustion of hydrogen and sustainable aviation fuels.
After a reminder of the classification of piston engines, this article focuses on the essential decarbonization of thermal machines by 2030 and beyond. The technological issues that govern the innovations of progress in hydrocarbon-free combustion engines are reviewed. The reactivation of old concepts of alternative engines appropriate to this new context concludes the discussion.
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