Comparison between Mach 2 rarefied airflow modification by an electrical discharge and numerical simulation of airflow modification by surface heating

Abstract

This study is devoted to numerical and experimental investigations about the influence of an electrical discharge over a flat plate immersed in a rarefied Mach 2 airflow. Regarding the experimental work, a negative dc discharge is created by applying a potential difference gap between two spanwise aluminum electrodes flush mounted on the plate. The electrode placed close to the leading edge is connected to the negative dc voltage, the second one is grounded. The influence due to the presence of the electric discharge is investigated with a glass Pitot tube by measuring the pressure proles above the flat plate. These experimental results are compared to the numerical work, where the effect of a surface temperature increase is simulated. Different effects can be attributed to the electrical discharge: the ionization of the gas above the plate with the creation of charged species, the acceleration of the positive charged species, the heat of the gas volume above the flat plate, and the heating of the surface of the flat plate. The Pitot probe measurements have shown a thickening of the boundary layer and the increasing of the angle of the shock wave, and the simulation of the surface temperature increase shows the same effect. These arguments let to think that the heating effect due to the temperature increase in the flat plate is the major one among the other effects mentioned above.

Effect of surface heating on shock wave modification by a plasma actuator in a rarefied supersonic flow over a flat plate

“…The flow had a uniform radial distribution through the test section with a core of 12 cm in diameter. 8 The nominal operating conditions, detailed in table 1, are: 63 Pa for the stagnation pressure and 8 Pa for the static pressure of the test section, corresponding to a geometric altitude of 67 km. 9 The Mach number M 1 of the gas flowing out of the nozzle was calculated with the classical isentropic relation.…”

“…In the case of the geometry studied here, one of the effects of a plasma actuator on the flow field is the heating of the surface. 8,12,36 The surface heating induces an increase in the flow viscosity close to the wall. 8 This modification is responsible for a displacement effect: 37 the laminar boundary layer thickens and, consequently, the shock wave is shifted outward of the flat plate surface (i.e., β increases).…”

“…8,12,36 The surface heating induces an increase in the flow viscosity close to the wall. 8 This modification is responsible for a displacement effect: 37 the laminar boundary layer thickens and, consequently, the shock wave is shifted outward of the flat plate surface (i.e., β increases). The numerical simulations of the surface heating show that β increases with the maximal value of the temperature surface T w,max (see figure 12).…”

Исследование Плазмодинамических Процессов Наносекундного Диапазона При Формировании Ударных Волн От Импульсных Разрядов

“…Особенностью таких разрядов является изменение состояния газа за короткое время протекания тока разряда и его быстрый нагрев в результате импульсного энерговклада. Часть электрической энергии, переходя-щая в тепловую энергию в микросекундном интервале времени после разряда, зависит от параметров разряда и свойств среды [1,2,4,5]. Газодинамические параметры течения зависят от мощности разряда и геометрии об-ласти энерговклада, взаимодействующей с потоком [5].…”

“…Часть электрической энергии, переходя-щая в тепловую энергию в микросекундном интервале времени после разряда, зависит от параметров разряда и свойств среды [1,2,4,5]. Газодинамические параметры течения зависят от мощности разряда и геометрии об-ласти энерговклада, взаимодействующей с потоком [5]. Инициирование горения с помощью плазмы основано на генерации активных частиц в плазменном объеме и быстром нагреве газа [6].…”