For engineers working in the field of aerospace, FLOW-3D provides valuable insight into fuel stability/ acquisition, cryogenic temperature regulation, PMDs, cavitation, and electric charge distribution through use of accurate liquid/gas interface (free-surface) modeling, thermal solutions with phase and electrostatics physical models.
Knowledge of the motion of propellants in the fuel tanks of spacecraft is essential to understanding various aspects of their operation and performance. Propellant motion impacts propulsion functions such as expulsion of liquid, venting of gases, and pressurization. In some cases the forces produced by the propellant motion must also be known. This is particularly true when the liquid mass is a significant portion of the total spacecraft mass.
Visualizing Non-Inertial Reference Frame Motion
FLOW-3D is an excellent software for simulating fuel sloshing dynamics because of the accurate free surface tracking using TruVOF. Additionally, FLOW-3D’s Non-Inertial Reference Frame (NIRF) module allows easy and computationally efficient setup for visualization of the fuel and the moving container (fuel tank) from a stationary frame of reference.
To highlight FLOW-3D’s NIRF module capabilities, a sample simulation showing the fuel sloshing in the space shuttle is set up. The space shuttle accelerates upwards for initial 25 seconds and then de-accelerates by the same amount for the next 25 seconds. After that, using angular acceleration, the shuttle rotates by 90 degrees and then continues to accelerate linearly again.
It is interesting to see the complex free surface fluid motion during this complicated space shuttle maneuver. The RNG turbulence model is used to estimate the turbulent kinetic energy of the fluid. The left pane of the animation shows NIRF visualization, while the right viewport shows the non-NIRF visualization. NIRF visualization helps to understand the motion of the fluid and the tank from a stationary frame of reference, hence highlighting the overall dynamics of the system in a more relatable way.
Many power systems used in spacecraft operate on liquid fuel which is stored in onboard fuel tanks. In order to function properly, these systems must be provided with a reliable supply of vapor-free fuel. Designing fuel acquisition systems which operate in a microgravity environment is very challenging since surface tension tends to control the motion and location of the fuel, making it difficult to guarantee it will be at the tank outlet when needed. Propellent management devices (PMDs) can be designed to ensure that vapor-free fuel is delivered to the power systems consistently. FLOW-3D enables designers of spacecraft to simulate real-world orbit maneuvers and design PMDs with a high degree of confidence. FLOW-3D provides users with well-validated physical models of surface tension and wall adhesion, free-surface advection and non-inertial reference frames.
Electric Charge Distribution
Sloshing of aircraft fuel in-flight or during refueling, generates electric charge, causing the fuel-vapor mixture at the interface to become conductive. Analysis of transient electric potential and field distribution helps to identify optimum discharge locations on the fuel tank. This electric charge distribution simulation using FLOW-3D demonstrates the fuel behavior inside an aircraft fuel tank while it accelerates through a turn in a series of yaw, pitch, and roll motions.