105: Laminar Flow Nozzle

Flow characterization has many useful applications in chemical and biomedical engineering industries. Laminar flow in water produces a glass-like presentation that is visually pleasing. We wanted to produce a consumer-grade level laminar flow nozzle device that retains this aesthetic quality but is comparable to other existing products which cost between $600 and $2000. 

To start, we developed a test model to analyze key design choices for the nozzle geometry while also maintaining laminar flow. We used the dimensionless Reynolds Number (Re) to characterize between laminar and turbulent flow, which is dependent on diameter. For laminar flow, the Re must be under 2300 and it decreases when diameter is also decreased. We developed a mathematical model utilizing Re to choose optimal nozzle geometry. To validate our model, we used COMSOL to ensure the flow was fully developed and laminar. To minimize Re, we used the smallest cylinder commercially available: a 3mm-diameter coffee straw.

For our prototype, we used common materials and drew inspiration from successful DIY experiments. The main body of the device is made from PVC and holds the straws in place. We used a hose adapter to attach the device to a garden hose. Before entering the straws, water passes through sponge and mesh which regulate the entering pressure created by the garden hose. Combining knowledge from DIY experiments and modeling, we reached our goal of designing a laminar flow nozzle that is affordable and aesthetically pleasing.