## Simple Excel sheet for calculating a flared port with NFR=0,5

I used basic geometry and the formulas by

salvatti/devantier/button and set up a simple excel sheet to calculate a flared port, providing

- effective surface area
- effective length
- enclosure tuning frequency
- suggested flare roundover radius

For convenience the user data to be fed into the calculator is

- effective exterior diameter, which can be defined using my method explained in post #595, based on strouhal number
- actual port length
- speed of sound
- and (net) enclosure volume

The excel sheet also includes a sketch indicating the geometry.

there are two warning fields that will turn yellow

- if the port length and the effective exterior diameter combination leads to intersection of flares (thus sealing the port)
- if the ratio between central minimum surface and exterior port surface is smaller than 1/10. this is just a safety feature based on my tests, where narrowing the central cross section area to 10% of port mouth area worked flawlessly. It might even be possible to extend this ratio

both warnings ask you to increase the effective exterior diameter or decrease the actual length.

NFR (normalized flare rate) is fixed to 0,5 for this first version, thus the flare radius is equal to the actual port length.

you can use your defined

*actual port length* and the calculated

*effective surface area* to feed a simulation tool of your choice with data for a equivalent tube port. the tuning of this simulation will be correct, but the air speeds / air particle displacement and the volume occupied by port will not.

The excel sheet is protected except user data fields just to avoid unintended changes, but there is no password protection, so feel free to unlock it!

If you find any bugs please let me know!

View attachment 1317588