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Study of Sloshing Impact on the Tanker Wall for Different Fluids with Varying Accelerations

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Study of Sloshing Impact on the Tanker Wall for

Different Fluids with Varying Accelerations

Ratna Kumar Gotru Dr. P. Ravindra Babu

PG Student Professor

Department of Mechanical Engineering Department of Mechanical Engineering

Gudlavalleru Engineering College, AP Gudlavalleru Engineering College, AP

Abstract

In this Thesis three types of fluids are used to study the effect of sloshing in a tanker. Sloshing is the phenomena that occur in a partially filled tanker. Sloshing is the periodical oscillations in a tanker due to the external disturbances. In some stable conditions sloshing generally leads to cyclic stress and fatigue in thin walled tank structures. If that effect is nearer to the natural frequency of the tanker then beating phenomenon takes place which leads to severe collapse. Earlier various studies were made experimentally and numerically to analyze the effect of sloshing on the fuel tank. In this work transient analysis is performed using ANSYS 14.5. A Sequence of numerical experiments has been carried out to estimate the pressure developed over the tanker wall and the free surface displacement of the fluids from its mean static level. Simulations are compared for the three different fluids to validate the effect of sloshing on the tanker. This is performed for variable accelerations and the results are compared. It was found from CFD transient simulation of fluids interface with tanker periphery.

Keywords: Sloshing, ANSYS, VOF, Elliptical fuel storage tanker

_______________________________________________________________________________________________________

I. INTRODUCTION

The tankers that are transporting undergo motion in the liquid due to its nature. When the tank is semi-filled or partially filled the fluid inside will slosh. Sloshing takes in different ways and there few mechanism that the liquid experience when it was subjected to external disturbances or excitations. This kind of slosh creates huge impact over the tanker body. Then the liquid will move to and fro. Such phenomenon is called as sloshing. If this sloshing frequency is equal to the natural frequency of the tanker body then beating phenomenon takes place. That leads to a blast or complete collapse of the tanker. Especially in aerospace applications these slosh loads will result the instability of the vehicle. These slosh loads will be experienced due to two main reasons, namely type of disturbance and due to the shape of the tanker. Due to sloshing hydro dynamic forces and moments will be posed on the tanker body that will cause cyclic loading on the tanker periphery.

II. MODELLING AND ANALYSIS

The tanker we consider for analysis follows Indian standard notation. The dimensions of the tanker are considered from IS 13187. Based on these dimensions we modeled the tanker in CREO PARAMETRIC 3.0 and analysis was carried in ANSYS Fluent 14.5. The dimensions are tabulated below in table-1

Table - 1 Specifications of the tanker

S. No Designation of tanker Dimensions in mm

1 Length (L) 4780

2 Width (W) 2236

3 Height (H) 1270

4 Thickness of the sheet metal (t)

3.3 (VOF< 25 liters) 5 Total Trailer Length (Lt) 4980

The model of the tanker is elliptical in shape which we can observe in fig 1.

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The above tank that is modeled using CREO PARAMETRIC 3.0 is exported to ANSYS for simulation. We use VOF (Volume of Fluid) method to execute the simulation because it allows arbitrary large deformations and enables free surfaces to evolve.

III. PROCEDURE

The physical model used for present study is shown in figure. Present model consists of a 3-dimensional liquid storage spherical tank which is partially filled with water (ρ=999.98kg/m3, μ=0.00103 kg/m-s). The tank dimensions are 2.236*1.27*4.78 m3. Water fill level in tank is 60% of total height of tank and the rest part is occupied with air. The tank is supposed to go under sloshing effect which creates pressure and forces on tank wall. During computation, pressure is monitored at a certain point on the right wall in order to record the sloshing loads. We investigated the effect of slosh impact pressures over the wall of the tanker by another types of fluids. The fluids like kerosene, water, and diesel are investigated to find the slosh impact over the wall. The properties that are considered are portrayed in table-2.

Table – 2

Standard Properties of fluids used for analysis

S. NO NAME OF FLUID

NAME

OF PROPERTY VALUE UNITS

1 DIESEL

DENSITY 730 Kg/m3

VISCOSITY 0.0024 Kg/(m-s) SPECIFIC HEAT 2090 j/(kg-.k)

THERMAL

CONDUCTIVITY 0.149 w/(m-k)

2 KEROSENE

DENSITY 780 Kg/m3

VISCOSITY 0.0024 Kg/(m-s) SPECIFIC HEAT 2090 j/(kg-.k)

THERMAL

CONDUCTIVITY 0.149 w/(m-k)

3 WATER

DENSITY 998.2 Kg/m3

VISCOSITY 0001003 Kg/(m-s) SPECIFIC HEAT 4182 j/(kg-.k)

THERMAL

CONDUCTIVITY 0.6 w/(m-k) Following procedure is followed in Fluent:

1) In setup, it is scaled to proper units if required and mesh quality is checked.

2) Pressure based transient solver is used with explicit formulation and gravitational field is enabled. 3) Multiphase model with volume of fluid (VOF) method is used, and turbulent model is considered. 4) Air and water are used as two different immiscible fluids and aluminum is used as solid material. 5) Air is considered as primary phase and water as secondary.

6) For sinusoidal motion of tank acceleration imposed in the form of momentum source input. 7) For simulation following operating conditions are chosen:

 Operating pressure:-101325 Pa  Gravitational acceleration: X= -9.81 m/s2

Y= 0 m/s2 Z= -9.81 m/s2

Operating density:-1.225 kg/m3

8) Baffle, baffle shadow and rectangular tank are considered as wall. 9) Following solution method is adapted:

Scheme- Fractional setup, Gradient-green-gauss node based, pressure-boy force weighted, momentum-first order upwind, volume fraction-geo-reconstruct

 Pressure-velocity coupling: Fractional step  Gradient: least square cell based

 Pressure: Body force weighted  Momentum: Power law

 Volume fraction: Geo-Reconstruct

 Transient formulation: Non-iterative time advancement 10) Non-iterative relaxation factor:-

 Pressure: 0.8  Momentum: 0.6

11) For filling of water in tank, region of cell is adapted and then adapted cell is patched by water.

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Time Stepping Method: Explicit formulation is used for simulation of sloshing. Hence for stability condition and avoid divergence, value of global Courant Number should not exceed 250. In variable time method:

 Global courant number-2,  Ending time-0.45,

 Min.time step factor-1e-05,  Max. Time step factor- 0.0025,  Min. step change factor- 0.5,  Max. Step changefactor-1.5.

This is the procedure for all the fluids with varying properties. At two gravitational accelerations 9.81 m/s2 and 15 m/s2 the results were plotted.

IV. RESULTS AND DISCUSSIONS

For acceleration=9.81m/s2

Fig. 2: Pressure Exerted on the Tanker Wall for Kerosene.

The minimum pressure on the wall is -4.3833e+12 [Pa] and the maximum exerted pressure on the walls of the tanker is 207.842 [Pa].

Fig. 3: Pressure Exerted on the Tanker Wall for Diesel.

The minimum pressure on the wall is -5.7363e+12 [Pa] and the maximum exerted pressure on the walls of the tanker is 201.654 [Pa].

For Water

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Fig. 4: Pressure Exerted on the Tanker Wall for Water.

Fig. 5: Comparison of Slosh pressures for different fluids.

As the density of the fluid increases the slosh impact pressure increases

.

For acceleration=15 m/s2

Fig. 6: Pressure Exerted on the Tanker Wall for Kerosene

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Fig. 7: Pressure Exerted on the Tanker Wall for Water

The minimum pressure on the wall is -1.55423e+10[Pa] and the maximum exerted pressure on the walls of the tanker is 257.692 [Pa].

Fig. 8: Pressure Exerted on the Tanker Wall for Water

The minimum pressure on the wall is -4.47032e+10[Pa] and the maximum exerted pressure on the walls of the tanker is 313.818 [Pa].

Fig. 9: Comparison of Slosh pressures for different fluids.

When the acceleration is applied at X= -15m/s2, Y= 0 m/s2, Z= -15 m/s2 the sloshing pressure that is experienced on the tanker

is gradually increasing. Here the properties of liquids are considered as the vital issue that influences the effect of slosh.

Diesel Kerosene Water

Pressures in

pascals

257.692 309.169 313.818

257.692

309.169

313.818

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Table - 3

Pressure Comparison when a=9.81 m/s2 and a=15 m/s2

S. No Name Of Fluid

Pressure at a= 9.81 m/s2

(Pascal)

Pressure at a= 15 m/s2

(Pascal)

1 Diesel 201.654 257.692

2 Kerosene 207.842 309.169

3 Water 259.016 313.818

Fig. 10: Slosh pressure plotting for three fluids at a= 9.81 and 15 m/s2

The liquid properties and tanker shape are responsible for the variation in the impact pressure that was created on the wall of the tanker.

V. CONCLUSION

Three fluids having disparate properties are supposed to periodical oscillations inside the tanker with gravitational accelerations

9.81 m/s2 and 15 m/s2 induced by the fluid to hit the tanker periphery. The acceleration is directly proportional to the slosh impact

pressure. Those cyclic high pressures will cause the failure of the tanker wall.

This present study based on the liquid properties and acceleration of the fluid through this computational study shows the effect of sloshing on the real life can definitely reduce the life of the material or may cause severe damage if it is a crude oil due to cyclic and sudden impacts.

REFERENCES

[1] Avin N. Mohan, (2014) “Finite Element Analysis on Trapezoidal Tank to Suppress Sloshing Effect,” Dissertation, presented to M. G University in partial

fulfillment of the requirements for the degree of M.Tech, [4, pp. 121-125].

[2] Puneet Kumar Nema, (2014) “Computational study of sloshing behavior in 3-D rectangular tank with and without baffle under Seismic Excitation”

Dissertation, presented to N. I. T Rourkela in partial fulfillment of the requirements for the degree of M.Tech, [5, pp. 23-27].

[3] P.K. Panigrahy, U.K. Saha, D. Maity 2009. “Experimental studies on sloshing behavior due to horizontal movement of liquids in baffled tanks.” Ocean

Engineering [36, pp. 213-222.]

[4] V. Singal , Jash Bajaj, Nimish Awalgaonkar, Sarthak Tibdewal (2014), “CFD Analysis of a Kerosene Fuel Tank to Reduce Liquid Sloshing”, Procedia

Engineering. [Vol 69: pp. 1365 – 1371].

[5] Krit Threepopnartkul, Chakrit Suvanjumrat, “The Effect of Baffles on Fluid Sloshing inside the Moving Rectangular Tank”, Journal of Research and

Applications in Mechanical Engineering. [Vol. 1 No.2].

[6] Dongming Liu, Pengzhi Lin 2009. Three-dimensional liquid sloshing in a tank with baffles. Ocean Engineering [36, 202-212].

[7] IS 13187 (1991) “Road tankers for light petroleum products” Chemical Engineering Plants and Related Equipment [15, pp. 1-2]

[8] T. Kandasamy, S. Rakheja, A.K.W. Ahmed, (2010), “An Analysis of Baffles Designs for Limiting Fluid Slosh in Partly Filled Tank Trucks”, The Open

Transportation Journal. [Vol. 4: 23-32].

[9] Derek Wilkinson, Brian Waldie, M.I. Mohamad Nor, Hsio Yen Lee (2000)“Baffle plate configurations to enhance separation in horizontal primary separators”

Department of Mechanical &Chemical Engineering, 6(4), 221-226

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[11] Rajamani Rajagounder, Guru Vignesh Mohanasundaram, and Prakasan Kalakkath “A Study of Liquid Sloshing in an Automotive Fuel Tank under Uniform Acceleration” ENGINEERING JOURNAL [Vol. 20 Issue 1: pp. 75].

[12] Armenio, V., Rocca, M.L., 1996. “On the analysis of sloshing of water in rectangular containers: numerical study and experimental validation.” Ocean

Engineering [23 (8), 705–739].

[13] Franklin T. Dodge, (2000) “TheDynamic Behavior of liquids in moving containers” Southwest Research Institute [202, pp. 5-19]

[14] Richard Klein, United States Patent 6,564,961 B1, 2003. [TRAPEZOIDAL FLUID STORAGE TANK].

[15] A.Vakilaad Sarabi & M. Miyajima “Project Zeus: Study of the Sloshing of Water Reservoirs and Tanks due to Long Period and Long Duration Seismic

Motions”Kanazawa University, Japan, Dept. of Earthquake Engineering Technical Report [15 WCEE, pp.6-8, 2012].

[16] Xue-lian Zheng, Xian-sheng Li, Yuan-yuan Ren, Yu-ning Wang, and JieMa. (2013). “Effects of Transverse Baffle Design on Reducing Liquid Sloshing in

Figure

Table - 1 Specifications of the tanker Designation of tanker Dimensions in mm
Table – 2 Standard Properties of fluids used for analysis
Fig. 2: Pressure Exerted on the Tanker Wall for Kerosene.
Fig. 6: Pressure Exerted on the Tanker Wall for Kerosene
+3

References

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