Locked Vortex Afterbodies

Little, Bryan; Whipkey, R. R.

doi:10.2514/3.58522

Cited by 63 publications

(30 citation statements)

References 4 publications

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“…Similar observations were made from experiments by Gharib and Roshko [16] in their axisymmetric cavity. Formation of shear layer for cavity flows is also discussed in the works of Little Jr. and Whipkey [17] and Graham and Xin [6]. This transformation is caused due to the interactions between mainstream flow and cavity flow.…”

Section: Cavity Flow Structurementioning

confidence: 93%

Characteristics of Turbulent Flow Past Passive Rectangular Cavity at Large Reynolds Numbers

Kumar

Mishra

2016

J. Inst. Eng. India Ser. C

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In the present investigation, turbulent flow past passive rectangular cavity is investigated numerically for four mainstream Reynolds numbers namely Re ms = 20,000-50,000. Validation study reveals that the numerical models used in the present investigation predicts the data close to the existing experimental results. Further attempts are made to bring out the flow structure in terms of velocity profile, velocity gradients, shear layer growth rate, and turbulence characteristics. Numerical results are analyzed to bring out the variation in the velocity profile at different axial locations within the cavity. Also, the velocity gradient, turbulence level at the shear layer and the reverse flow velocity in the cavity are found to be sensitive to the mainstream Reynolds number. Finally, the cavity drag is estimated and its relation to the pressure drop across the cavity is brought out. These results reveal the nature of interaction between the passive cavity flow and mainstream flow. Keywords Passive cavity flow Á Trapped vortex Á Shear layer List of Symbols D c Cavity drag V i Velocity (m/s) V ms Mainstream velocity (m/s) V r;max Maximum reverse flow velocity (m/s) q Density (kg/m 3 ) k Turbulent kinetic energy (m 2 /s 2 )

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Section: Cavity Flow Structurementioning

confidence: 93%

Characteristics of Turbulent Flow Past Passive Rectangular Cavity at Large Reynolds Numbers

Kumar

Mishra

2016

J. Inst. Eng. India Ser. C

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“…In order to trap a stable vortex, Little and Whipkey [3] proposed an optimal cavity aspect ratio based on the minimum drag condition on the after-body. However, the effect of mass injection into the cavity was not considered by Little and Whipkey [3] in their experiments. Cavity injection is important for combustion applications as it would enhance the interactions between the cavity and the mainstream flows [4,5].…”

Section: Introductionmentioning

confidence: 99%

“…An optimally designed cavity traps a vortex which is spatially and temporally stable over a wide range of inflow conditions [2]. In order to trap a stable vortex, Little and Whipkey [3] proposed an optimal cavity aspect ratio based on the minimum drag condition on the after-body. However, the effect of mass injection into the cavity was not considered by Little and Whipkey [3] in their experiments.…”

Section: Introductionmentioning

confidence: 99%

Numerical study of flame/vortex interactions in 2-D Trapped Vortex Combustor

2014

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The interactions between flame and vortex in a 2-D trapped vortex combustor are investigated by simulating the Reynolds averaged Navier-Stokes equations, for the following five cases: (1) non-reacting (base) case, (2) post-vortex ignition without premixing, (3) post-vortex ignition with premixing, (4) pre-vortex ignition without premixing, and (5) pre-vortex ignition with premixing. For the post-vortex ignition without premixing case, the reactants are mixed well in the cavity resulting in a stable C shaped flame along the vortex edge. Further, there is insignificant change in the vorticity due to chemical reactions. In contrast, for the pre-vortex ignition case (no premixing); the flame gets stabilized at the interface of two counter rotating vortices resulting in reduced reaction rates. There is a noticeable change in the location and size of the primary vortex as compared to case (2). When the mainstream air is premixed with fuel, there is a further reduction in the reaction rates and thus structure of cavity flame gets altered significantly for case (5). Pilot flame established for cases (2) and (3) are well shielded from main flow and hence the flame structure and reaction rates do not change appreciably. Hence, it is expected that cases (2) and (3) can perform well over a wide range of operating conditions.

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“…While the former is helpful in improving the ballistic performance [2] the latter is beneficial in enhancing the missile stability and fin control effectiveness [1]. The control methods include both active and passive strategies such as bleeding [2][3][4], burning [5], boat-tailing [2,6], base cavities [7][8][9][10], ventilated cavities [1,9], locked vortex afterbodies [11], grooved cavities and rounded bases [12], porous wall [13], serrated trailing edges [14], etc. Out of these, boat-tailing [1,2,9] is the simplest method to reduce base drag in various bluff body models, aircraft fuselage structures, missile afterbodies.…”

Section: Introductionmentioning

confidence: 99%