Dynamics of dual-pulse laser energy deposition in a supersonic flow

Abstract

Dynamics of plasma generated by the dual-pulse laser in a supersonic flow was studied numerically. The mathematical model includes species, momentum, electronic, vibrational and translational energy equations for the multicomponent ionized air. The model examines temporal dynamics of the formed air plasma and how it affects the drag, pressure signature and vorticity generation in a supersonic flow around a wedge. We observed that nonequilibrium plasmas is more effective in the drag reduction compared with the simultaneous thermal energy addition. The maximum drag reduction of around 50% and the maximum drag coefficient reduction of 30% was attained through the dual-pulse laser energy deposition. Variation of the plasma spot orientation did not significantly influence the drag reduction. We suggested that the surface pressure changes were not controlled by the vorticity generation but occurred due to the density changes and the formation of the low-density plasma spot.

Mechanism of nonequilibrium plasma-enhanced ignition in the event of dual-pulse laser energy deposition

“…In the early stage of DPL ignition, the laser plasma is in a nonequilibrium state because a significant part of the laser energy at an electron temperature of approximately 1 eV is spent on the vibrational excitation of nitrogen molecules. Recent results also suggest that the dualpulse-based system can ignite a mixture in turbulent flow considering an extremely high initial degree of ionization [53], enhanced flow control, and drag reduction in supersonic flows [54,55], and can support a plasma-enhanced deflagration to detonation transition (DDT) [56]. Numerical studies of DPL ignition in a frame of one-and two-dimensional (2D) threetemperature plasma models have shown that the initial electron number density pattern created by the first laser pulse can tailor the ignition kernel dynamics.…”

Флуктуации Плотности И Температуры За Фронтом Ударной Волны При Воздействии Стратифицированного Источника Энергии

“…В [6] доказывается возможность плазменного воздействия на процесс обтекания тела при помощи короткоимпульсного газового разряда, который увеличивает температуру электронов, оставляя при этом неизменной температуру газа. В [7] на основе неравновесной модели двойного лазерного импульса установлено, что с увеличением степени ионизации происходит уменьшение силы сопротивления поверхности тела. Возможность воздействия на ударную волну однородной газоразрядной среды экспериментально исследована в [8].…”