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High-Speed Supersonic and Hypersonic Engines
Published in Ahmed F. El-Sayed, Aircraft Propulsion and Gas Turbine Engines, 2017
Turboramjet engines are not as common as the pure ramjet engine. Two famous such engines may be identified. (Most of the others are either secret or only in experimental phases.)P&W J58-1, continuous-bleed afterburning turbo (145 kN), two of which powered the SR-71 strategic reconnaissance aircraft (1964–1998). This enabled it to take off under turbojet power and switch to ramjets at higher super-sonic speeds. Cruise speed was between M = 3 and M = 3.5.The ATREX turboramjet engine [13].The ATREX was developed in Japan. As shown in Figure 7.27, the airflow is pressurized inside the engine by an air fan, while the liquid hydrogen (fuel used) is pressurized by a turbopump. Highlights for both flows are given here.Air flow: The air intake that reduces the velocity of incoming air at a high flight Mach number. Next, this air is cooled down by the pre-cooler. The cooled air is pressurized by a fan and injected into the combustion chamber through the mixer together with the hydrogen discharged out of the tip turbine. The plug nozzle provides the effective nozzle expansion over the wide range of the flight environment.Hydrogen (H2) flow: The hydrogen supplied from the storage tank is pressurized by a turbopump and heated regeneratively in the pre-cooler.
Supersonic Gas Injector for Plasma Fueling in the National Spherical Torus Experiment
Published in Fusion Science and Technology, 2019
V. A. Soukhanovskii, W. R. Blanchard, J. K. Dong, R. Kaita, H. W. Kugel, J. E. Menard, T. J. Provost, R. Raman, A. L. Roquemore, P. Sichta
Four axisymmetric nozzle shapes are commonly used for making high-quality supersonic gas jets: a converging nozzle (free jet), a converging-diverging Laval nozzle, a converging-diverging conical nozzle, and an aerospike (plug) nozzle (e.g., Ref. 8). In comparison with a simple converging nozzle,25 a shaped Laval nozzle can produce a highly uniform flow with constant Mach number, temperature, and density—the conditions favorable for molecular condensation. A higher flow intensity can be obtained with a lower pressure ratio in a contoured (Laval) nozzle avoiding problems associated with normal Mach disk shocks. The Laval nozzle shape must be properly calculated to optimize the isentropic flow core and minimize the thickness of the boundary layer. This is usually done using the method of characteristics or computational fluid dynamics methodology based on numerical solution of the Navier-Stokes equations.23 The nozzle design is based on an established flow with steady-state parameters. For tokamak fueling applications, pulsed gas jet operation may be desirable; hence, the finite flow settle time may limit the minimum pulse length.