Jump to content
HybridZ

robtpt

Members
  • Posts

    3
  • Joined

  • Last visited

About robtpt

  • Birthday 04/13/1981

robtpt's Achievements

Newbie

Newbie (1/14)

10

Reputation

  1. The recirculation at the inlet is basically unavoidable. Whether you taper it or not, the area expansion is too great and the flow will separate. The best solution is to match the area of the manifold to the area of the inlet pipe as closely as possible. This will result in smaller recirculation regions. Look at the flow visualization on the stock manifold that was posted earlier as a good example of that. With as large of an area expansion as there is in this manifold, the taper could actually be worse than the step. When the flow separates and creates a recirculation region, the air flowing back towards the inlet sees a converging duct and is actually accelerated back out of the manifold. You can also see that quite clearly in the flow visualization that was posted earlier. While the step is an imperfect solution, it does at least prevent the back flow since the air in the recirculation zone can't make back out past that step.
  2. JustinOlson and veritech-z, I think you both have valid points. I can understand how the protruding velocity stacks could be helpful. However, I do think veritech-z is correct about the fact that the velocity stacks don't protrude into the main part of the flow. They just sort of stick up in the boundary layer. I've been thinking about suggestions as to what might help the OP redesign, and I have the following thoughts: 1. He should add a length of pipe to the inlet of his model. The fluid dynamics of air being sucked into that hole are going to be VERY different if it's just a hole or if it's a length of pipe running into the intake manifold. Even a short length of pipe would be helpful. 2. An abrupt edge at the inlet may be better than the taper. The flow will definitely separate either way, but at least an abrupt edge will keep the separation point fixed for all flow conditions. 3. I would also play around with the amount the velocity stacks protrude. I accept your explanation of their benefit 100%, but if they protrude TOO much they will definitely disturb the flow.
  3. I'm a grad student in mechanical engineering and I've spent a lot of time looking at flow visualizations in water and wind tunnels, so I'll give you my thoughts. I have no experience designing intake manifolds, though, so take anything I say with a grain of salt. It seems to me the two biggest problems are the protruding velocity stacks and the abrupt expansion right after the inlet. Pipe flow will tend to separate and go turbulent when there is a large area expansion, like there is at your inlet. Also, the protruding velocity stacks are bound to cause separation and turbulence. I don't know if it is common in this type of EFI intake, but I would think it would be a lot better to have the face of the velocity stacks flush with the surface of the intake manifold rather than protruding into it.
×
×
  • Create New...