Unsteady transitions of separation patterns in single expansion ramp nozzle

Yu, Yang; Xu, Jianzhong; Yu, Kaikai; Mo, Jianwei

doi:10.1007/s00193-015-0595-y

Cited by 19 publications

(2 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Restricted shock separation with the separation bubble forming on the flap (RSS (flap)) will be present in SERN with a lengthy flap. In a previous study [15], the authors observed the transition from RSS (ramp) to RSS (flap) during the nozzle shutdown process, as illustrated in Figure 1. The transition was instantaneous, which resulted in a mutation in nozzle performance and hindered stable flight.…”

Section: Introductionmentioning

confidence: 83%

The Influence of External Flow Field on the Flow Separation of Overexpanded Single-Expansion Ramp Nozzle

Yu,

Mao,

et al. 2023

Aerospace

View full text Add to dashboard Cite

Flow separation and transitions of separation patterns are common phenomena of nozzles working with a wide Mach range. The maximum thrust method is applied to design the single-expansion ramp nozzle (SERN) for specific operating conditions. The nozzle is used to numerically simulate the transition processes of separation patterns under the linear change in the external flow Mach number and the actual trajectory take-off condition of a rocket-based combined cycle (RBCC), to investigate the mechanism through which the external flow field influences the separation pattern transition during acceleration. The computational fluid dynamics (CFD) method is briefly introduced, followed by experimental validation. Then, the design procedure of SERN is described in detail. The simulation results indicate that as the external Mach number increases, the flow field in the nozzle undergoes transitions from RSS (ramp) to FSS, and finally exhibits a no-flow separation pattern. The rate at which the external Mach number varies has little effect on the transition principle of the nozzle flow separation patterns, but it has a significant effect on the critical Mach number of the transition points. The external flow field of the nozzle has an airflow accumulation effect during acceleration, which can delay the transition of the flow separation pattern.

show abstract

Section: Introductionmentioning

confidence: 83%

The Influence of External Flow Field on the Flow Separation of Overexpanded Single-Expansion Ramp Nozzle

Yu,

Mao,

et al. 2023

Aerospace

View full text Add to dashboard Cite

show abstract

“…Both passive and active jet control methods have been researched and used in a variety of aerospace applications. Passive jet control methods used either geometrical modifications of the nozzle like use of cross wire, 1,2 notches, 3,4 tabs, [5][6][7] chevrons, [8][9][10] grooves, 11,12 expansion ramps, 13,14 or modifying the exit shape. [15][16][17][18][19] Active control methods employed some kind of actuator assisted device to interact with the jet to achieve jet control by changing the jet structure dynamically.…”

Section: Introductionmentioning

confidence: 99%

Effect of flat wall length on decay and shock structure of a supersonic square wall jet

Tammabathula

Ghanta

Bandla

2021

Proceedings of the Institution of Mechanical Engineers, Part G:

View full text Add to dashboard Cite

Experiments were conducted to find the effect of wall length on the decay behaviour and shock structure of a supersonic wall jet issuing from c-d nozzle of the square-shaped exit. A straight flat wall of width same as the side length of the square was attached to the lip of the nozzle such that the leading edge of the wall and the side of the square aligned properly which allowed the supersonic jet to graze past the flat wall. Experiments were conducted with five different wall lengths, that is, [Formula: see text] = 0.5, 1, 2, 4 and 8. Wall pressure measurements were made from leading edge to the trailing edge of the wall along its centreline. Schlieren flow visualization of the jet flow over the wall for the different wall lengths revealed the shock pattern and the effect of the wall length on the shock structure. The shock structure and jet deflection were significantly affected due to the presence of the wall. There was an upward jet deflection for [Formula: see text] up to [Formula: see text] whereas a downward jet deflection was observed for [Formula: see text]. Noticeable changes in the shock structure were observed for the wall lengths up to 2 D h. The wall length also significantly affected the jet decay characteristics and supersonic core length. Maximum enhancement in jet decay and maximum reduction in supersonic core length resulted when the wall length was [Formula: see text]. However, when the wall length was increased to [Formula: see text], there was a significant reduction in jet decay and a recovery of [Formula: see text]. Presence of wall always resulted a reduction in Lsc irrespective of wall length. The wall effect was to induce a more precipitous pressure drop closer to the nozzle exit, and a more gradual drop farther from it for [Formula: see text] > [Formula: see text].

show abstract