In previous message I attached a drawing for a Nozzle.
DO YOU KNOW how to calculate the Nozzle throat dimensions ?.
It has an error and it is the lower lip that says 1/8 clearance WRONG the clearance should be, as closest as, as possible to the edge of the turbine blades to reduce the splash or water escaping from the Nozzle.
You have 3.78 l/s, though no information about minimum and maximum water volume levels that can be used to see if the Banki needs 1, 2 or even 3 Nozzles to cover water variations.
Checking the Banki, it seems that the blades angle are too steep, how did you define this angle, how did you calculate it ?.
Why the 45 Cm Banki length ?. How did you design for such length ?.
The drawing is for a 6 1/8 inch Banki radius, so you need to convert this to the radius of your Banki RATIO for all the dimensions, except the angles that stay the same.
The length of the Nozzle lip, depends on the number of blades, this nozzle is for 45 degrees coverage for 3 blades minimum.
This coverage can be seen on the drawing that is formed by the radius of the Banki plus the setting of the offset point of 1 3/4 inches from the radius point forming the secondary Radius, of 7 inch, that goes down to the lower lip covering point .
The THROAT of the Nozzle is located at the Junction where the 1/4" steel plate that is at 90 degrees to the Banki and the end of the 6"R external curve of the Nozzle, and at the UPPER end of tHE 6.354 degrees angle
The throat WIDTH of the Nozzle is defined by these two radius and the LENTGH of the Nozzle then is defined by the water volume and the head of the system .
The upper 6" MOUTH can be varied, depending on the water volume and the pipe coupled to the nozzle.
This nozzle should be made with variable adjustment to carefully setting to the Banki edges to make sure that there is a tight coupling - a somewhat long hose ( flexible) would be ideal for such settings.
Make the Plaster of Paris and adjust the dimensions by shaving ir or adding more plaster until you get the body as you need, then cover it with fiberglass, including the curved area for you to cut later, some place external ribs to make the lip stiff and as el at the end a rib horizontal to the lower lip to avoid lip curving due to the water pressure.
Nando