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An adiabatic process (adiabatic from Ancient Greek ἀδιάβατος (adiábatos) ' impassable ') is a type of thermodynamic process that occurs without transferring heat between the thermodynamic system and its environment. Unlike an isothermal process, an adiabatic process transfers energy to the surroundings only as work and/or mass flow.
As the gas is compressed, the heat of compression is rapidly transferred to the thermal mass, so the gas temperature is stabilized. An external cooling circuit is then used to maintain the temperature of the thermal mass. The isothermal efficiency (Z) [13] is a measure of where the process lies between an adiabatic and isothermal process. If ...
A free-turbine turboshaft is a form of turboshaft or turboprop gas turbine engine where the power is extracted from the exhaust stream of a gas turbine by an independent turbine, downstream of the gas turbine. The power turbine is not mechanically connected to the turbines that drive the compressors, hence the term "free", referring to the ...
In such a case, the exhaust gas retains a pressure which is higher than that of the ambient air. This is the source of 'pressure thrust'. The rate of flow of fuel entering the engine is often very small compared with the rate of flow of air. [11] When the contribution of fuel to the nozzle gross thrust can be ignored, the net thrust is:
In gas dynamics we are interested in the local relations between pressure, density and temperature, rather than considering a fixed quantity of gas. By considering the density ρ = M / V {\displaystyle \rho =M/V} as the inverse of the volume for a unit mass, we can take ρ = 1 / V {\displaystyle \rho =1/V} in these relations.
Closed-cycle gas turbine schematic C compressor and T turbine assembly w high-temperature heat exchanger ʍ low-temperature heat exchanger ~ mechanical load, e.g. electric generator. A closed-cycle gas turbine is a turbine that uses a gas (e.g. air, nitrogen, helium, argon, [1] [2] etc.) for the working fluid as part of a closed thermodynamic ...
Under other conditions, free-energy change is not equal to work; for instance, for a reversible adiabatic expansion of an ideal gas, =. Importantly, for a heat engine, including the Carnot cycle , the free-energy change after a full cycle is zero, Δ cyc A = 0 {\displaystyle \Delta _{\text{cyc}}A=0} , while the engine produces nonzero work.
The difference between the exhaust and intake pressures and temperatures means that some increase in efficiency can be gained by use of a turbocharger, removing from the exhaust flow some part of the remaining energy and transferring that to the intake flow to increase the intake pressure. A gas turbine can extract useful work energy from the ...