Control of the Formation of a Transonic Region in an Axisymmetric Supersonic Flow with the Use of a Jet and a Near-Wall Energy Supply
28 Feb 2020-Journal of Engineering Physics (Springer US)-Vol. 93, Iss: 1, pp 136-144
TL;DR: In this paper, the authors investigated the control of a throttling air jet produced by a gas generator and of the energy sources positioned at the walls of an axisymmetric channel, which models the combustion-chamber unit of a ramjet in which a gas flow is decelerated, on the shock-wave structure of a supersonic gas flow in the channel for the purpose of formation of a lengthy transonic region.
Abstract: The control action of a throttling air jet produced by a gas generator and of the energy sources positioned at the walls of an axisymmetric channel, which models the combustion-chamber unit of a ramjet in which a gas flow is decelerated, on the shock-wave structure of a supersonic gas flow in the channel was investigated for the purpose of formation of a lengthy transonic region in it. A heat energy was supplied to the gas flow in the indicated channel in the pulse-periodic regime, and the pressure in the gas generator was also changed periodically. The range of energies corresponding to a stable transonic flow regime in the channel was determined on the basis of solution of the nonstationary Euler equations in dimensionless variables. For comparison, the combustion of a gaseous fuel inflowing to the channel through a slot in the channel wall upstream of the control air jet was considered. A nonstationary gas flow in the channel was calculated on the basis of the Reynolds-averaged Navier–Stokes equations with the use of the k–ω SST model of turbulence. It is shown that a controllable energy release in the channel, providing the obtaining of a transonic flow regime in it analogous to that obtained on the basis of solution of the Euler equations, can be realized with the use of a control transverse air jet.
TL;DR: In this article, a single shot of pulsed nanosecond dielectric-barrier discharge plasma actuator with varying pulse voltages in quiescent air was studied by experiments and numerical simulations.
Abstract: The shock wave behavior generated from a single shot of pulsed nanosecond dielectric-barrier-discharge plasma actuator with varying pulse voltages in quiescent air was studied by experiments and numerical simulations. The experiments included using the schlieren technique, a fast response pressure transducer, and a two-velocity-component particle image velocimetry system to measure the propagation of the shock wave, the shock overpressure, and the shock induced flow, respectively. For the numerical simulation, a simple “phenomenological approach” was employed by modeling the plasma region over the encapsulated electrode as a jump-heated and pressurized gas layer. The present investigation revealed that the behaviors of the shock wave generated by the nanosecond pulsed plasma were fundamentally a microblast wave, and their speed and strength were found to increase with higher input voltages. The blast wave occured about 1 to 3 μs after the discharge of the nanosecond pulse, which was dependent on the inpu...
TL;DR: The technique studied in this work has weighty potential for high-speed combustion applications, including cold start/restart of scramjet engines and support of transition regime in dual-mode scramjet and at off-design operation.
Abstract: The results of experimental study of plasma-based mixing, ignition and flameholding in a supersonic model combustor are presented in the paper. The model combustor has a length of 600mm and cross s...
TL;DR: In this article, mixing enhancement in a M=2 crossflow using the transient high-pressure, high-temperature, and high-velocity pulse from a detonation was investigated experimentally.
Abstract: Mixing enhancement in a M=2 crossflow using the transient high-pressure, high-temperature, and high-velocity pulse from a detonation was investigated experimentally High-frame-rate shadowgraphy and planar laser-induced fluorescence of the nitric oxide molecule showed the structure and time-dependent interaction of the detonation plume with the supersonic flow The high-momentum flux from the detonation provided significant penetration, with blowdown times of 4–8 ms achieved Planar laser-induced fluorescence of nitric oxide captured the spanwise structure of the plume and the large counter-rotating vortex structure for enhanced mixing The upstream jet was shown to be drawn into the pulse detonator’s plume, providing distribution to the core supersonic flow Significant coupling between a continuous upstream jet and the pulse detonator plume was found and indicated that there was an optimal staging distance for enhanced mixing
TL;DR: In this paper, a new reformulated production limiter considering the efforts of strain rate tensor and rotation tensor is proposed for the Scale-Adaptive Simulation method (SAS), while two other limiters only considering strain or vorticity are also conducted for comparison.