FLOW-3D offers simulation solutions to many of the challenges in the automotive industry, including transient flow dynamics, (both free-surface and confined), thermal energy transfer in fluids and solids, phase change, 6-degrees of freedom motion of solids and a coupled finite element solver for mechanically and thermally induced stresses.
Traditional areas of interest for the automotive industry include: fuel tank sloshing, underhood thermal management and spray control, early fuel shut-off during fill, degas bottles, fluid resistance of powertrain components, and casting of automotive parts.
Other analysis capabilities include:
- An electrostatic model that can capture a charge distribution with time
- Fuel level indication using the Moving Objects model with 6 degrees of freedom to capture float variations
- Fuel line pressurization
- Optimal location of vents
Fuel tanks in automotive vehicles are crucial for safely storing fuel. They also ensure constant and adequate supply for various operating loads of a vehicle in motion. The tanks can be complex in shape to ensure compact packaging with vehicle chassis design and body panels. When the vehicle accelerates through driving conditions, the fuel sloshes within the tank triggering a challenge to fuel level gauges, pressure and delivery systems. Fuel filling is critical at pumps where the vapor compressibility in the tank can cause undesired early shutoff of filling nozzle. In addition, static electricity can be conveyed into the fuel tanks resulting in rise of electric potential within fuel system. FLOW-3D helps simulate these complex multi-phase, multi-physical, transient scenarios to aid fuel system design and improvement.
In this video, FLOW-3D‘s non-inertial reference frame model is used to simulated sloshing in a partially filled fuel tank. The simulation allows designers to predict the forces and moments on the tank as well as predict how much fuel enters the filling tube. With this information, appropriate baffle systems can be placed inside the tank to minimize sloshing forces.
Early Fuel Shut-off
Fuel tank filling systems are typically designed with a wide filling tube where the nozzle is inserted and fuel is pumped into the tank. The filling tube may follow an irregular path between the nozzle and the tank to allow it to fit compactly into the vehicles suspension and structural members. This path can inhibit fuel flow, causing fuel to backup and trip the fuel overflow sensor at the nozzle. FLOW-3D‘s TruVOF interface tracking method accurately predicts where vapor bubble may become trapped in the filling tube so that designers are able to design the nozzle holder so that fuel flows as straight as possible down the tube. The animation at the right shows a 3D and 2D view of a filling scenario in which vapor bubbles become trapped in the filling tube and pressurize, forcing fuel to flow back up to the nozzle, tripping early shutoff.
Fluid resistance is an area of interest to designers of rotating systems in fluid. FLOW-3D has a fully coupled, 6-degree of freedom model that can simulate numerous objects all moving in conjunction. The model calculates and outputs resistive data in terms of total resistance, pressure resistance and viscous resistance. The Moving Objects model that enables this capability is fully parallelized for efficient simulation times. Also, the way FLOW-3D‘s numerics are applied means that object collisions and efficiency of motion are optimized. Finally, many types of constraints can be assigned including, axial and rotational constraints, applied forces and torques, collisions based on friction and a coefficient of restitution, and tethering with springs or ropes.
FLOW-3D‘s porous media model is well suited for simulating flow in filters. There are a number of drag formulations which can be applied to determine optimal designs, which will capture particulates well and minimize drag. Particles can be introduced with a range of sizes or mass to determine the trajectory of the particulates.
Data output that can be analyzed includes velocity profiles, residence time, distance traveled by fluid, strain rate, and stream lines. It is also easy to extend the capability to predict clogging and the resulting additional drag through customization. Flow Science offers a number of numerical routines available for modification.
Degas bottles are crucial components of automotive engine coolant systems, used to de-aerate the coolant fluid during its passage. These bottles consist of several chambers and have a complex geometry based on underhood compactness and vehicle design. It is important to study air entrainment, settling and sloshing behavior of coolant fluid during vehicle acceleration.
FLOW-3D is used to analyze the multiphase behavior of sloshing coolants within a running automotive coolant system. Coolant fluid within each chamber through time can be tracked and any interference with either the cap or vents can be analyzed. The simulation below shows transient velocity magnitude contours and air entrainment during an active filling and sloshing simulation.