First CFD Tests
We learned so much from this, and the results seem promising.
The first test yielded poor results. This allowed me to make some pretty significant changes to the part geometry in order to produce a good flowing part. The main issue was the gap between the leading edge of the air horn and the outer wall of the plenum being too small. There wasn’t any air flowing through it. Below are the results of the test with updated geometry.
Test parameters:
1 bar pressure at the inlet
215 CFM flow at the outlet (Cyl 4)
The test returned with a maximum air speed of 227 ft/s. Airflow detachment was noticed at the end of the small radius bend as it approached the straight section near the volume outlet. Detachment was also noticed near the divider that separates the direct air from the air that curves along the outside perimeter. This is due to a discontinuous change in the radius leading up to the divider. Air is escaping from the inlet tube section into the horns adjacent to the one calling for air and wrapping around the many different surfaces leading up to the appropriate intake horn. Constantly moving flow can be witnessed inside the plenum around the outside surface, and airflow direction looks largely uniform overall. The reduced surface area between the outsides of the straight section of the runners is causing the air to move in a direction that opposes the direction of the primary air volume. A teardrop-shaped outer surface may be of benefit in this area.
Design Goals for Tri-Speed Intake System V1:
Increase center-to-center distance from ITB dimension to head port dimension
(Will require custom ITB linkage or different ITB’s)
Maximize radii of inner and outer curves
Introduce angle into air inlet tube to remove perpendicularity of inlet face and cross-section of inner/outer convergence point
(Air inlet will end up pointing slightly towards the ground, interference with fuel rail will be main design restriction)
Include full length of runner all the way up to head port in simulation
Scan engine bay to visualize interference points
Resonant frequency tuning is coming soon!
Check out the video below for more details on the project.