Rankine Vortex Suppression in Tanks with Conical Base: A Numerical Investigation

Prabhu, Mahadev; Sreenath, Koushil; Kumar, R. Ajith; Jayakumar, J. S.; Joshy, P. J.

doi:10.2514/1.a34794

Cited by 17 publications

(5 citation statements)

References 21 publications

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Section: Introductionsupporting

confidence: 94%

“…The reduced acceleration field (low acceleration due to gravity) increases the critical height and concluded that critical height in spherical bottom tank is higher than that in flat bottom tanks by 80% at a swirl velocity of 10 rad/s. These results are complying with the results of Prabhu et al 5,24 It is established by previous investigators that based on strength and weight considerations, spherical monolithic tank design is more efficient. This is the reason for the use of spherical bottom tanks in liquid rocket systems.…”

Section: Introductionsupporting

confidence: 92%

“…Prabhu et al 4 reported new parameter to characterize Rankine vortex formation in a liquid draining tank and found that critical height enhances with increase in port diameter. Prabhu et al 5 studied vortex suppression in tanks with conical base and mentioned that an increase in Froude number will increase the critical height till it reaches a maximum value, and further increase in Froude number reduces critical height.…”

Section: Introductionmentioning

confidence: 99%

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Analytical models for critical heights of vortexing in flat and spherical bottom tanks with siphon and bottom drains

Nageswaran,

Prabhu,

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part G:

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Critical height or critical submergence is liquid level at which air-core vortex extends from the free surface into drain hole when a liquid is drained from a container/tank. Extensive analytical and experimental studies have been reported on critical height of bath tub vortex, for liquid draining downward from flat bottom propellant tanks. Rockets making use of liquid propellants mostly employ spherical bottom propellant tanks as well as siphon or upward drain flow. Keeping in view of such practical applications, analytical models are developed for critical height, considering the effects of siphon drain and the shape of tank bottom. Additional design parameters influencing the behavior for each case are identified. Appropriate governing equations and a solution methodology are developed pertinent to the system considered, to predict the critical height for siphon drain and spherical bottom tank independently as well as for both combined. The results indicate that the critical height for spherical bottom tank is higher than for flat bottom tank, due to higher local flow velocity. Siphon geometry can be designed for critical height much less than normal drain from flat bottom tank. These observations are in accordance with the results published in the literature. This paper reports the analytical models and solution methodology to predict the critical height for vortexing for normal draining from spherical tank bottom, siphon draining from both flat and spherical bottom tanks.

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Section: Introductionsupporting

confidence: 94%

Section: Introductionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Analytical models for critical heights of vortexing in flat and spherical bottom tanks with siphon and bottom drains

Nageswaran,

Prabhu,

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…It can now be inferred that, reduced pressure at the vicinity of the drain port is the major cause for ingesting air from the ambient to form air core vortex and this complies with the observation of previous investigators. 10,21,22 ∂r ∂t + 1 r…”

Section: Resultsmentioning

confidence: 99%

Air core vortexing in liquid draining tanks: Influence of surface roughness

Prabhu

Nair²,

Kumar

2022

Proceedings of the Institution of Mechanical Engineers, Part C:

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This paper study the influence of roughness of the tank base in the formation of air core vortex when liquid inside the cylindrical tank is rotated and subsequently drained. The vortex air core formation in drain tanks can lead to the blockage of drain port and can result in reduced discharge of draining liquid as an immediate consequence. The formation of such a vortex in propellant tanks of spacecraft and rockets will lead to underutilization of propellants and can adversely affect the performance of rocket engines. Ingestion of air core vortex in metal casting process can affect the mechanical properties of casted metal. Hence, suppression of air core vortex is inevitable in the fields of aerospace, metal casting and other hydraulic engineering systems. Current study makes use of roughness of the tank base to suppress vortexing which is the first of its kind and therefore, novel. Experimental investigations have been carried out at several values of roughness height and initial fluid rotation to study the characteristics of air core vortex. It is found that at the highest value of initial rotation provided to the liquid, air core vortexing can be subdued up to 25% by making use of base roughness. Current study also recommends drain tank manufacturers not to smoothen the tank base surface spending time at extra cost. In addition, applying roughness on the tank base will further weaken the formation of air core vortex, in the light of this study.

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“…The study of induced or shedding vortices by the bluff body is also useful in a variety of other aerospace applications, such as noise reduction in exhaust nozzles 32 and liquid drain in fuel tanks [33][34][35] . The induced vortices over the different bluff body shapes have also been investigated by some of the researchers computationally and experimentally to understand the unburnt species mixing 36,37 as well as the stability of the flame 38 .…”

Section: Introductionmentioning

confidence: 99%

Unsteady dynamics in a subsonic duct flow with a bluff body

George,

Karthick,

Srikrishnan

et al. 2022

Preprint

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A series of reduced-order numerical simulations on a specific bluff body type (v-gutters) in a subsonic duct flow is done to assess the unsteady wake dynamics. Two of the v-gutter's geometrical parameters are varied: the v-gutter's base angle (θ ) and the size of a slit (ξ ) at the leading-edge of the v-gutter. Turbulent flow kinematics and pressure field are analyzed to evaluate the unsteadiness at a freestream Mach number of M ∞ = 0.25 and a freestream Reynolds number based on bluff body's transverse length (L) of Re L = 0.1 × 10 6 . Five v-gutter angles are considered (θ , • = π/6, π/4, π/3, 5π/12, π/2) and three slit sizes (ξ , mm =0,0.25,0.5) are considered only for a particular θ = [π/6]. In general, high fluctuations in velocity and pressure are seen for the bluffest body in consideration (θ = π/2) with higher drag (c d ) and total pressure loss (∆p 0 ). However, bluffer bodies produce periodic shedding structures that promote flow mixing. On the other hand, the presence of a slit on a streamlined body (θ = π/6) tends to efficiently stabilize the wake and thus, producing almost a periodic shedding structure with lower c d and ∆p 0 . For θ = [π/6], broadened spectra in vortex shedding is seen with a peak at [ f L/u ∞ ] ∼ 0.08. For θ ≥ [π/4], a dominant discrete shedding frequency is seen with a gradual spectral decay. Similarly, the effects of ξ on the θ = [π/6] case produce a discrete shedding frequency instead of a broadened one, as told before. The shedding frequency increases to a maximum of [ f L/u ∞ ] ∼ 0.26 for the maximum slit size of ξ = 0.5. From the analysis of the x − t diagram and the modal analysis of vorticity and velocity magnitude in the wake, the peaks are indeed found to agree with the spectral analysis. More insights on the shedding vortices, momentum deficit in the wake, varying energy contents in the flow field, and the dominant spatiotemporal structures are also provided.

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Rankine Vortex Suppression in Tanks with Conical Base: A Numerical Investigation

Cited by 17 publications

References 21 publications

Analytical models for critical heights of vortexing in flat and spherical bottom tanks with siphon and bottom drains

Analytical models for critical heights of vortexing in flat and spherical bottom tanks with siphon and bottom drains

Air core vortexing in liquid draining tanks: Influence of surface roughness

Unsteady dynamics in a subsonic duct flow with a bluff body

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