Investigation of base flow for an axisymmetric suddenly expanded nozzle with micro JET

Abstract

This investigation presents the outcome of the tests conducted to control the pressure in the re-circulation zone. Also, the efficiency of the flow controllers to govern the pressure at the base in a rapidly expanded pipe has been investigated. Tiny jets our in number of 1 mm diameter are positioned at the interval of 90 degrees at 6.5 mm from the central axis of the main jet. The Mach numbers of the abruptly expanded flows studied for base pressure range from 1.1 to 3 and the obtained wall pressure distribution is depicted for Mach number 1.6 and 1.8 respectively. Axi-symmetric round brass tubes were used to join jets; and cross-sectional area of those tubes are 2.56. L/D ratio of the broadened pipe was differed from 1 to 10 and NPR was shifted from 3 to 11. Notwithstanding, the outcomes displayed were for Low L/D values of 4, 3, 2 and 1 individually. Also, when the stream was released to the pipes of the given area ratios, it stayed connected with the channel divider for all the inertial levels and the NPRs tried in the present case. Further it is understood that level of expansion assumes a noteworthy part to choose the pressure at the base and its control adequacy. At whatever point, the stream is over expanded, it leads to the formation of an oblique shock at the nozzle lip, prompting improvement of the pressure in the base locale. Shock waves formation, reflection and recombination proceeded till the pressure winds up noticeably environmental and seen that the stream stays intact for low L/D ratio of 4. Very small scale (micro) jets proved to fit in as controllers for the base pressure.

A Critical Review of Supersonic Flow Control for High-Speed Applications

“…For the Mach numbers ranging from 1 to 3, the effect of the microjet control in the CD nozzle with a sudden expansion duct was experimentally tested at supersonic Mach numbers. The research varied nozzle parameters, such as an area ratio of 2.56; NPR ranged from 3 to 11; and L/D ranged from 10 to 1 [94]. They extended their work for Mach 2.5 and 3.0, and cross-sectional areas of 2.56, 3.24, 4.84, and 6.25; the L/D ratio of the duct was 10 to 1, and the NPR used were from 3 and 11 [95].…”

Effect of Micro Jet Control on the Flow Filed of the Duct at Mach 1.5

“…Chaudhary et al [10], [11] studied the consequence of the tests pertinent to the flow control at the base in the recirculation zone. Micro jets of one-millimeter orifice diameter placed at ninety-degree separation at a PCD of 1.3 times at the periphery of the CD nozzle having exit diameter of 10 mm in the base region were employed as the dynamic control mechanism.…”

“…Experimentally investigated the microjets control duct for an area ratio of 7.56 [13], 2.56 [14], 3.24 [15], [16], 4.84 [17]. Also, the results were numerically simulated and validated with the experimental results [10] and also, simulated the base pressure reattachment lengths for different flow condition (i.e., Mach number, area ratio, and the level of expansion) [18].…”