Resistance Characteristics of Submerged Projectile with Bow Variation based on Hull Envelope Equation using Steady RANS Simulation
Published at : 29 Jul 2019
Volume : IJtech
Vol 10, No 4 (2019)
DOI : https://doi.org/10.14716/ijtech.v10i4.2156
Yanuar., Ibadurrahman., Putri, S.A.A. 2019. Resistance Characteristics of Submerged Projectile with Bow Variation based on Hull Envelope Equation using Steady RANS Simulation. International Journal of Technology. Volume 10(4), pp. 677-688
| Yanuar | Department of Mechanical Engineering, Faculty of Engineering, Universitas Indonesia, Kampus UI Depok, Depok 16424, Indonesia |
| Ibadurrahman | Department of Mechanical Engineering, Faculty of Engineering, Universitas Indonesia, Kampus UI Depok, Depok 16424, Indonesia |
| Syifa Alfiah Andini Putri | Department of Mechanical Engineering, Faculty of Engineering, Universitas Indonesia, Kampus UI Depok, Depok 16424, Indonesia |
This paper investigates the influence
of the forebody of a projectile-shaped model without appendages and propulsion system in a submerged condition. The
commercial steady RANS code, ANSYS Fluent, was used to conduct the simulations,
and the forebody was varied based on the Hull Envelope equation. From the
results, the model with nf = 2.75 was
the optimum design according to the bow efficiency coefficient. However, the model
with a blunt form (nf = 1) produced the lowest drag because it had the least wet surface area. For models with high nf, a high accelerating flow led to a
low-pressure condition after the impact of the fluid on the fore end. This
soaring pressure difference caused a flow separation, and therefore the fullness of the forebody affected the fluid flow around the body: the alteration of pressure, the flow speed, and friction as the primary
component of resistance.
Bow shape; Hull envelope coefficient; Resistance characteristic; Steady RANS; Submerged projectile
The resistance of a submerged
object has a significant influence on its speed and acoustic signature, and
hence its endurance. Viscous resistance is the only component of total drag on
a deeply submerged object and is divided into two elements: skin-friction
resistance and form (viscous pressure) resistance (Renilson, 2015). One way to reduce these resistances in the
initial design stage is to consider the hull form of the vehicle in terms of
its hydrodynamic aspect (Joubert, 2004).
Generally, the hull of a submerged object or submarine
consists of three sections: the forebody, middle body and aft body (Burcher & Rydill, 1994). The “Hull Envelope”
formula, the first developed equation for a true teardrsop shape, is essential
in the concept design stage (Jackson, 1992). Other designers have used different hull form
equations for submerged objects or submarines, but they have still been associated with the teardrop shape
(Kormilitsin & Khalizev, 2001). The forebody of a submerged object determines
the stagnation point (location and pressure) of the flow. Moreover, the bow
shape has a significant influence on the behavior of fluid flow around and
after it, thus affecting the effectiveness of sensitive
equipment in it, e.g. acoustic or navigation equipment.
Following previous studies, an experiment on a submerged spheroid was conducted by Farell et al. (1973) in order to examine the influence of body form on the resistance components. Besides, a wind-tunnel experiment on a high-speed underwater object reasonably demonstrated that an ellipsoidal nose profile could improve hydrodynamic performance (Suman et al., 2010). A wind-tunnel observation of a submersible vehicle also showed a typical flow separation in the symmetric bow of a submarine model with an angle-of-attack variation (Saeidinezhad et al., 2015).
The use of Computational Fluid Dynamics
(CFD) has gained increasing favor in recent decades, during which time
computing power and improvements in numerical algorithms have been improving
significantly; Using CFD could straightforwardly construct a virtual towing tank or wind tunnel (Yang & Löhner, 2003; Toxopeus, 2008; Fedor, 2009;
Gross et al., 2011). The commercial CFD code ANSYS had been
used to
investigate an autonomous underwater vehicle and has resulted in a propeller race deduction (Rattanasiri et al., 2015). Another CFD approach showed that the
elliptical submarine nose-shape was preferred for an initial design (Moonesun et al., 2016). Furthermore, Siswantara et al. (2016) have
proven that the CFD method could be used for various digester designs to find
that which is optimal in terms of slurry flow; they modelled in two dimensions
to reduce the complexity of the calculations.
Investigation of
a moving submerged object has focused mainly on achieving an optimum design by
identifying the body form. Work using 2D steady-state flow RANS (Reynold Averaged
Navier-Stokes) with variants of forebody shape and the speed range is well
underway; the commercial CFD software ANSYS Fluent had been utilized in this
study. The objective of this paper is to examine the characteristics of
resistance and flow influenced by the bow form. The result may help designers
at a concept design phase. The scope of the study focuses only on the forebody
form of a projectile-like object in deeply submerged conditions, with the only
drag components considered important being skin friction and viscous pressure
resistance.
The
design of a submerged object depends on hydrodynamic aspects; the forebody is
one of the critical concerns since flow of fluid toward the bow influences the
remaining body. In this paper, CFD simulations of 2D submerged projectile
models were conducted to examine this issue. The results provide a reasonable estimate
of the resistance and flow characteristics of the models.
The
model with nf = 1 produced the lowest total drag since
its wet surface area was smaller than that of the other models. However, the
ellipse models attained better flow properties, and that
with nf = 2.75 was designated as the
optimum design according to the bow efficiency coefficient. The pressure point
on the front end became extensive for higher nf models, thus making the pressure difference rise dramatically. On the ellipse models, the
flow velocity increased from a point one-fifth along
the bow length after the high pressure on the front end when the bow-head
displaced the fluid. Subsequently, the rising velocity of the flow reduced the
fluid pressure, thus creating a slight separation
The
study has shown that a simplified CFD method using a commercial code could be a functional assessment of designing a
submerged object at the initial stage. The optimum design based on the results
of this study is suitable for projectile-shaped objects in deeply submerged conditions, such as submarines and
torpedoes. Any
consideration omitted from this paper may slightly revise the results.
Furthermore, involving additional analysis, such as the relation of the fluid around the bow to propulsion efficiency, would be considered worthy of examination, since the form of a hull affects the wake formation behind the self-propulsion object, as well as its resistance (Suastika et al., 2017).
This work is sponsored by the Ministry of Research, Technology, and
Education of Republic Indonesia (NKB-1791/UN2.R3.1/HKP.05.00/2019).
ANSYS, 2009. ANSYS FLUENT 12.0: Theory Guide, ANSYS,
Inc.
Burcher, R., Rydill, L.J.,
1994. Concepts in Submarine Design.
Cambridge, UK: Cambridge University Press
Cao, L., Zhu, J., Zeng, G., 2016. Viscous-flow Calculations of Submarine Maneuvering Hydrodynamic
Coefficients and Flow Field based on Same Grid Topology. Journal of Applied Fluid Mechanics, Volume 9(2), pp. 817–826
Chen, Y., Lu, C.-j., Cao, J-y., Chen,
X., 2012.
Application of Quadratic and Cubic Turbulence Models on Cavitating Flows around
Submerged Objects. Theoretical &
Applied Mechanics, Volume 24(6),
pp. 823–833
Farell, C., Guven, O., 1973.
On The Experimental Determination of the Resistance Components of Submerged Spheroid.
Journal of Ship Research, Volume
17(2), pp. 72–79
Fedor, R., 2009. Simulation of a Launch and Recovery of a UUV
to a Submarine. Adelaide, Australia: Royal Institute of
Technology KTH
Marina System
Gross, A., Kremheller, A.,
Fasel, H., 2011. Simulation of Flow over Suboff Bare Hull Model. In: 49th AIAA Aerospace
Sciences Meeting including the New Horizons Forum and Aerospace Exposition, American Institute of Aeronautics and
Astronautics
Jackson, H., 1992. Fundamental
of Submarine Concept Design. SNAME,
Volume 100, pp. 419–448
Joubert, P.N., 2004. Some Aspects of Submarine Design. Part 1,
Hydrodynamics. Fishermans Bend, Vic: DSTO Platforms Sciences Laboratory
Kim, D.-H., Park, W.-G., Jung,
C.-M., 2012. Numerical Simulation of Cavitating Flow Past Axisymmetric Body. International Journal of Naval Architecture
and Ocean Engineering, Volume 4(3), pp. 256–266
Kormilitsin, Y.N., Khalizev,
O.A., 2001. Theory of Submarine Design.
Riviera Maritime Media
Moonesun,
M., Korol, Y.M., Nikrasov, V.A., Ursalov, A., Brajhko, A., 2016. CFD Analysis of
the Bow Shapes of Submarines. Journal of
Scientific and Engineering Research, Volume 3(1), pp. 1–16
Rattanasiri,
P., Wilson, P.A., Phillips, A.B., 2015. Numerical Investigation of a Pair of Self-propelled
AUVs Operating in Tandem. Ocean
Engineering, Volume 100, pp. 126–137
Renilson,
M., 2015. Submarine Hydrodynamics. Lanceston,
Australia: Springer
Saeidinezhad,
A., Dehghan, A.A., Dehghan Manshadi, M., 2015. Experimental Investigation of Hydrodynamic
Characteristics of a Submersible Vehicle Model with a Non-axisymmetric Nose in Pitch
Maneuver. Ocean Engineering, Volume
100, pp. 26–34
Siswantara,
A.I., Daryus, A., Darmawan, S., Gunadi, G.G.R., Camalia, R., 2016. CFD Analysis
of Slurry Flow in an Anaerobic Digester. International
Journal of Technology, Volume 7(2), pp. 197–203
Suastika, K., Nugraha, F., Utama, I.K.A.P., 2017. Parallel-middle-body
and Stern-form Relative Significance in the Wake Formation of Single-screw
Large Ships. International Journal of
Technology, Volume 8(1), pp. 94–103
Suman, K., Rao, D.N., Das, H.N., Kiran, G.B., 2010. Hydrodynamic Performance
Evaluation of an Ellipsoidal Nose for a High-speed Underwater Vehicle. Jordan Journal of Mechanical and Industrial
Engineering, Volume 4(5), pp. 641–652
Toxopeus,
S., 2008. Viscous Flow Calculation for Barehull DARPA SUBOFF submarine at
Incidence. International Shipbuilding
Progress, Volume 55(3), pp. 227–251
Yang,
C., Löhner, R., 2003. Prediction of Flows Over an Axisymmetric Body with Appendages.
In: International Conference on
Numerical Ship Hydrodynamics, Busan, Korea
Yanuar, Ibadurrahman, Waskito, K.T., Karim, S., Ichsan, M., 2017. Interference Resistance of Pentamaran Ship Model with
Asymmetric Outrigger Configurations. Journal of Marine Science and Application, Volume 16(1). pp. 42–47