Energy

Sloshing in Large Scale Containers

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Sloshing is a problem that cannot be ignored in engineering design, such as the layout of fuel tank suction points, the structural safety of LNG boats in waves, and the analysis of dynamic loads in liquid metal cooled reactors under seismic conditions. In a partially filled liquid container under dynamic conditions, the dynamic pressure generated by the internal liquid sloshing affects the stability and integrity of the container itself. As a rapidly developing technology, CFD has been widely used for sloshing analysis in large-scale engineering design.

These complex geometries require days and weeks of simulation setup with traditional CFD tools for an experienced engineer. With shonDy a typical sloshing simulation with a complex geometry is setup in about half a day.

The bulk of LNG ship transport containers can reach 260,000 cubic meters. When such liquefied natural gas is affected by ocean conditions, the counteraction of rocking to the hull is an issue that engineering design must consider. In the nuclear field, liquid metal coolants such as LBE or lead, which have high densities, will interact with the pressure vessel under seismic conditions. The shaking liquid metal will generate a large dynamic load on the internal structures of the reactor. The magnitude of this dynamic load is related to the frequency and amplitude of the earthquake and the structural design within the reactor. LNG ships and LBE reactors are large-scale engineering vessels. The most important engineering problem under sloshing conditions is the dynamic pressure load inside the vessel.

Using our advanced simulation software shonDy, you only need to simply import the geometric model of the container and the initial area of ​​the fluid, and then input the displacement velocity and angular velocity of the container over time, and you can quickly start the calculation. No meshing and VOF models are needed. shonDy naturally calculates the free interface of the fluid.

In order to verify the accuracy of shonDy, the SPHERIC experiment conducted by A. Souto-Iglesias (2011) was used as a Benchmark study. In this experiment, a rectangular vessel was partially filled with dyed liquid. The vessel swayed left and right around the center point of the bottom. The angular velocity was sinusoidal, and the maximum rotation angle was 6 degrees. Pressure detectors were installed on the side walls and on the top of the test vessel to record changes in wall pressure over time.

Comparison of wave shapes: Experimental photographs(A. Souto-Iglesias (2011)) and simulation results by shonDy.
Comparison of dynamic pressure load: Experimental data and a simulation with shonDy.

The simulation results show that shonDy can accurately obtain the free water surface and dynamic load of the liquid under sloshing conditions.

The following is a demonstration of two engineering applications simulated with shonDy:

LNG tank sloshing.
LBE coolant sloshing in advanced reactor.
Pressure field in LBE reactor (more than 6 million particles).
Applications

Rotate it, gearbox!

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shonDy is an innovative industry ready simulation technology for fluid solid interaction in the case of gearbox lubrication. The flow of oil driven by gears in a gearbox rotating at a high speed is a problem of the interaction between a rigid body and a fluid. In the design of gearboxes, the movement of lubricating oil is one of the core issues.

Why do we simulate gearboxes?

The level of lubricant in the gearbox is a very sensitive parameter, that has to do with the working speed and spatial arrangement of the gear. If the gear level is too low, gear lubrication will be insufficient, causing the gear to overheat and shorten its life. If the oil level is too high, the viscous resistance of the system will be too great, affecting the efficiency of the gearbox. In addition, the distribution of lubricating oil in the box under working conditions will also affect the lubrication performance.

 

Advantages and limitations of shonDy for gearbox simulations

1. No additional modification of the geometry is needed. The production ready CAD model can be used as the input to shonDy. No mesh generation is involved.

2. Under normal circumstances, regardless of gas phase motion, lubricating oils are treated as single-phase fluids. It is impossible to simulate air friction here. Non-contact interactions are related to the particle radius and are rather a numerical error than a feature of the solver. Of course, our shonDy solver supports multi-phase flow calculations. If necessary, gas-liquid two-phase simulations can also be attempted.

3. We know that our costumers want to study the oil film on the teeth as well. If the oil film distribution and movement on a certain tooth is analyzed separately, such as the local flow of oil sprayed onto a single gear, this can be simulated and analyzed. However, for the overall simulation of the gearbox, the calculation scale of the single teeth and its oil film are too different from the whole system and we cannot get both at the same time. Usually, we do a separate simulation of single teeth to get the oil film if desired by the costumer.

 

 

Velocity field in the gearbox.
Free surface of the lubrication oil.
Automotive

Car hit by water wave

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In the scenario of a tsunami or flood, the vehicles may be hit by the water wave. shonDy can be applied to simulate the water wave which hits the car. The pressure field on the car surface can be obtained to estimate the potential damage on the car.

Energy

Core catcher | molten corium relocation

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During the severe accident in the nuclear power plant, the reactor core will melt due to the decay heat. In the late phase, the molten core material starts to relocate to the lower head of reactor pressure vessel (RPV). After the RPV wall is melted through, the molten corium can be diluted by a sacrificial material and then spreads to the cooling compartment. During the relocation of the molten material, the decay heat is transported with the corium material. One of the key phenomena is the process of phase change between solid as well as the liquid state of different involved materials.

Here is a simulation result of the hypothetical accident scenario achieved with shonDy:

The boundary conditions used for this case reveal the massive size.

Boundary conditions for melt spreading simulation.

 

Academic

Sloshing of fluid in container

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Sloshing refers to a common engineering problem. For example, in the design of a ship for the transportation of liquid natural gas, sloshing has to be taken into account. Another example is the containment water tank of modern GEN III nuclear reactors under seismic excitation. In this case, the impact force from the sloshing water to the containment building should be analyzed.

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