Rotate it, gearbox!

Posted on

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.

Core catcher | molten corium relocation

Posted on

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.



Sloshing of fluid in container

Posted on

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.