In our previous blog post, we walked through the process of setting up an airflow study over the front of the Thunder Roadster. We used SOLIDWORKS Flow Simulation to set up a computational fluid dynamic (CFD) analysis to verify that incoming air is adhering to the surface of the car and entering the hood scoop at racing speeds. With the results verified, the next step is to design new inlet components to route as much of that air to the engine as possible to improve performance.
|Flat area below hood scoop in question.|
Designing the Inlets
Before this project, our Application Engineer, Ryan Zeck, had been racing the car in an open-air configuration. Turbulent flow and higher temperatures in the engine bay can affect the air that reaches the intake manifold and take a toll on performance. One approach to solve this is to design a way to increase the flow of air going into the hood scoop rather than directly into the engine.
Having the right geometry is important to ensure that a retrofit design will work. To design the inlets for the engine we could use 3D scanning, but the process would yield a lot more data and information that what is needed for the few angles the modification requires.
After some brainstorming, Ryan decided to use different basic modeling tricks such as Insert Sketch Picture in SOLIDWORKS to make sure that the inlets would fit the engine.
|Insert Sketch Picture allowed Ryan to use a scaled picture of the actual manifold during design to ensure precise fitment.|
The rest of the inlet design was completed, using simple modeling strategies. A mockup of the intake manifold in SOLIDWORKS allowed for the dimensions of the inlets to match exactly the engine configuration. In addition, Ryan decided to design a clamping style collar to allow for easy removal of the parts, if needed.
|SOLIDWORKS Assembly showing inlets and collars|
Manufacturing the Inlets
After the design was complete, the next step was to manufacture the inlets. Computer Numerical Control (CNC) machining the inlets from billet aluminum or a similar material would be expensive and time-consuming. A multi-axis machine would increase the production cost tremendously as well as use too much material. Ryan decided to look at TriMech’s line of Stratasys FDM 3D printers to manufacture the inlets. The printer produced a sturdy piece that won’t melt and will direct airflow.
FDM Technology vs. PolyJet Technology
FDM technology uses a thermoplastic filament that is extruded through a hot nozzle. Once melted, the material is immediately set and layered on a plate. The machine head repeats the extruding and melting, layer by layer until the part is complete. If you plan on testing your parts in a strenuous process, FDM may be the better choice. Thermoplastics specialize in high tensile strength and resistance to high temperatures.
The PolyJet technology process is different in that a photopolymer is sprayed onto a plate, which is then immediately cured by a UV light. After a thin layer is created, the process repeats itself by jetting additional layers until the part is fully formed. Stratasys 3D printers powered by PolyJet Photopolymers provide levels of detail and realism in their finished products that exceed other 3D printing technologies. It is the only technology with the ability to both simulate a variety of materials and engineering plastics and combine colors and material into one finished product.
PolyJet parts have exceptional detail and a smooth finish, however, FDM printers have more material options for parts needing greater durability. In this case, we were more concerned with functionality over aesthetics due to the environment in which the inlets will be used. Therefore we decided to make the parts, and a prototype test jig, using one of our FDM printers.
|One of the inlets made in a Stratasys FDM Printer, showing model material (blue) and removable support material (black)|
Installing and Testing the Inlets
Before printing out the entire inlet, Ryan wanted to make sure his design was accurate to clamp the pieces to the inlet. He decided to print out an oval that would go into the inlet instead of printing out the entire piece. This helped in avoiding the use of too much support material. This prototyping step helped him confirm the piece was the right size and would fit into the car. Taking this step helped Ryan save time and figure out how to attach the inlet to the car.
|Inlets installed on the Hayabusa Engine, with piping to help direct the air from the hood scoop|
|Ryan installing an inlet on the Thunder Roadster|
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