CFD analysis of liquid sloshing in fuel tank for a tanker truck manufacturer in USA

Business Needs.

• Optimize tanker truck structural design to withstand the motion.
• Determine proper placement of baffles to reduce sloshing effect in tank.
• Compare results of container with and without baffles to optimize design.
• Reduce cost of physical destructive testing and design iterations.

Challenges.

• Flammable fluid adds to the risk of explosion due to hydrodynamic pressure and load exerted by the free surface of the fluid in partially filled closed rectangular tank.
• During the transportation, sloshing of fuel and accelerated motion of automobile threatens the structural integrity of the container.
• Simulate high frequency flows to capture high frequency waves understanding interaction of fuel and air inside the container to optimize the design.
• Time dependent variations in oscillating velocity of tank made it difficult to simulate and capture actual scenario.

HitechDigital’s Solution.

CFD experts at HitechDigital predicted liquid sloshing in tanker truck by conducting CFD analysis using VOF (Volume of Fluid) model along with realizable k-epsilon turbulence model. Dynamic mesh was utilizedto capture oscillatory motion of the tank partially filled with water. Simulation was carried out for multiple tank rolling cases to capture water sloshing inside the enclosed rectangular tank. Results of the CFD simulation improved tank design by adding baffles and reduce the sloshing effect & ensured stability of the truck while in motion.

Approach.

• 3D CAD model of the rectangular tank was prepared using SolidWorks and mesh model in ANSYS.
• HitechDigital CFD experts developed a fluid domain and applied dynamic mesh.
• Boundary conditions for fuel [kerosene] and gas [air] were applied for VOF [Volume of Fluid] model.
• To capture turbulence effects, realizable k-epsilon model was selected.
• Constant linear acceleration of 5m/s2 was assumed to capture the flow physics and sloshing effect inside the enclosed tank assuming the initial rest state of fluid and automobile for both the cases of with and without baffles.
• Mesh sensitivity analysis was also performed to ensure accuracy in the results.

Benefit.

• Effects of sloshing during the motion at regular time intervals after the automobile is set to motion [both acceleration and deceleration – during the application of brakes] helped the client set deisgns.
• The results showed possibility of weight shifts that can lead to instability and affect the safety.
• It further enabled the client to determine proper placement of baffles at appropriate locations in the tank to reduce the sloshing effect.

Client Speaks.

We were involved in the CFD/FEA analysis from other service provider for many years but finally we benefited from HitechDigital – they have so much to offer.

Result.

• Reduction in physical test trials which saved significant costs and development time.
• Optimized tank design with baffles could be made for safety.
• Ease in transit of carrier fluid without the risk of hazardous situations.