Simulation of rotor flows is extremely expensive, as the rotor wake, and its effect of the following blades, needs to be captured accurately. Hence, the development of appropriate flow-solver and grid generation technology is vital.
A multiblock structured grid generation tool has been developed at Bristol, which is applicable to fixed-and rotary-wing cases.
Some example meshes are shown below for hover and forward flight cases.
Sample grid planes for four bladed hover case (4 million points)
Grid in rotor disk and block structure at hub for forward flight case (8 million points)
A multiblock upwind flow-solver has also been developed and applied to rotor flows. The code can be run as unsteady, using an efficient implicit scheme and, and includes mesh motion and deformation schemes for unsteady flows with moving surfaces. As these flows are very expensive to compute, the code has been made more efficient by adding multigrid acceleration and has also been parallelised using MPI (Message Passing Interface).
Some solutions are shown below.
Four bladed hover solution (32 million points) Left. Four bladed forward flight solution (32 million points) Right.