ME Summer Design Project: Pasta-Inspired Fluid Mixer

Inspired by the unusual shapes of pasta, this project explores a creative approach to mix separate fluids flowing through a pipe. These shapes will be fitted into a pipe to act as a static inline mixer.

Motivation

The client for this project was a research team led by Dr. Pellegrino from the ME department at CU Boulder. They wanted an innovative design approach for an inline static mixer that is cheap to produce and reliable to be used in testing fluids mixing.

The design was inspired from observing an everyday objects and, specifically, the interesting shapes of pasta. With the versatility and the increasing accessibility of 3D printing, it was chosen to be the method of production. The unique material characteristics of thermoplastic-polyester (PLA) used in 3D-printing gave the opportunity to use Snap-Fitting mechanism.

Snap-Fit

The Snap-Fit mechanism gave the advantage of minimizing the number of parts needed in the assembly. One of the main aspect of this project was to find the best design/method to snap each piece with the other. Choosing the right 3D-printer and the right material was crucial in this process. After researching and several iterations, an annular/cylindrical snap-fit design was chosen to be implemented because of the degree of freedom it gives the shape's orientation around the pipe axis.

Pasta Design

Another important aspect was to be able to implement the pasta shapes in a way that it will disturb the flow of the fluids and evenly mix them. Using a CAD program (Solidworks), I was able to experiment with all the possible shapes and went through a rapid prototyping process.

Challenges

The biggest challenge faced in this project was finding the right sizes and clearances for the snap-fit two parts. First, I printed the first prototype with roughly estimated clearances. Then, I started to sand the connection part down to find the right diameter that best suits the material rigidity and elasticity behaviour.

My approach was to try to minimize the variables and keep them consistent throughout the prototyping process. If modification is needed, I tweaked one variable at a time until I reach the optimal measurements. This method allowed for a more systematic approach where I could spot and explain any improvements in the design. Also keeping a journal of all the iterations helped me quickly visit and build upon previous ideas.

Next Steps

The next step of this project is to print a final batch and test the different designs and how durable they would be with the fluids flowing through them in a 1-in PVC pipe. From there, the best design will be approved to be used in Dr. Pellegrino research with any necessary modification to it.