Infrared absorption imaging of 2D supersonic jet expansions: Free expansion, cluster formation, and shock wave patterns

Abstract

N2O/He gas mixtures are expanded through a 10 × 0.5 mm(2) slit nozzle and imaged by direct absorption vibrational spectroscopy, employing a HgCdTe focal plane array detector after interferometric modulation. N2O cluster formation in the free supersonic expansion is visualized. The expansion structure behind the frontal shock is investigated as a function of background pressure. At high pressures, a sequence of stationary density peaks along a narrow directed flow channel is characterized. The potential of the technique for the elucidation of aggregation mechanisms is emphasized.

Nuclear Spin Symmetry Conservation in 1H216O Investigated by Direct Absorption FTIR Spectroscopy of Water Vapor Cooled Down in Supersonic Expansion

“…The theoretical ratio of integrated absorbances A f i /A f i was calculated using the relationship (19) into which the CF parameter was substituted either assuming it equals 1 in the case of Fast conversion or equation (23) in the case of Slow conversion. The values of J quantum number, the energy of the low lying level of a selected transition and the line intensities S N f i (296K) were taken from HITRAN database.…”

“…The values of J quantum number, the energy of the low lying level of a selected transition and the line intensities S N f i (296K) were taken from HITRAN database. 32 Note that the line strengths F f i that enter formula (19) were calculated from line intensities S N f i (296K) reported in Table 2.…”

The temperature and size distribution of large water clusters from a non-equilibrium model

“…[12][13][14] In some special cases, an elegant spectrometric approach to cluster temperatures is possible, based on the measurements of rotational temperatures. [15][16][17] Another approach makes use of Laval nozzles with a fixed geometry. In that case, the thermodynamic parameters are constant in the flow.…”

Причины Свечения Аномального Вторичного Потока В Сверхзвуковых Кластированных Струях, Возбужденных Высоковольтным Электронным Пучком

“…Экспериментальное моделирование процессов истечения газов из сопел в вакуум или сильно разреженное пространство является актуальной и сложной научно-прикладной задачей [1][2][3]. Особую сложность при моделировании на малогабаритных установках течения из/вблизи сопел реальных космических аппаратов представляет воспроизведение условий истечения газов.…”