It is an important part to burn fuel energy without waste.
The fuel nozzle is closely related to the combustion chamber to be attached.
Its role is to provide a stable particle spray over a wide range from low output to high output.
There are various types of fuel nozzles, but the current mainstream is "spray type",
Two types of are used.
(1) Simplex fuel nozzle (2) Duplex fuel nozzle

These atomization methods are nearly identical, the difference being single or double.
The high-pressure fuel sent from the fuel system is distributed circumferentially in the nozzle and sprayed from the central injection hole via the swirl passage.
Then, compressed air is introduced from the outer periphery of the nozzle to promote atomization, and unburned fuel is blown off when the engine is stopped to prevent carbon deposition.
That is, the duplex fuel nozzle corresponds to the engine that supplies the primary fuel and the secondary fuel.
This model is to illustrate the basic structure of the "duplex fuel nozzle".
The fuel nozzle is closely related to the combustor, but the manufacturing technology is different, so it is manufactured by a specialized manufacturer who specializes in precision parts.
Parts with fine and precise holes are assembled in an overwrapping manner, but the surface is super-precision processed (lapped) to prevent leakage between the parts.

A. Features of this model
① Enlarged Cutaway model
In order to idetify primary and secondary passages by color, several times larger than the real thing is made.
It can be disassembled and assembled, and details such as swirl paths can be confirmed.
② Overall Assembly model (1/2 size of ①)
The passages from the primary and secondary connectors to the tip are separated.
Holes and swirl grooves that affect flow rate and spray pattern are not calculated and designed.
Unfortunately, leaks between the passages could not be prevented. (due to 3D printer’s accuracy)
It is possible to disassemble and assemble the nozzle parts.
Simple Flow test to check parts are assembled properly is introduced.

In addition, there are "Evaporator Tube type nozzle" and "Centrifugal type" which sprays using centrifugal force from the center of the rotor, used for the early engine.
At present, research on new combustors and fuel nozzles is being conducted in various engines to further reduce pollution, and I think a completely new system will emerge.

B. Assembly Manual (PDF format, total 12 pages)
The detail assembly manual including "Parts-List", "After printing treatment" and "Assembly procedure" are prepared based on "Standard Skill (Filing, Drilling, Tapping, gluing and tightening)".

C. Download files includes;
- Files: STL Files (26 items)
STL file name: "ws" of last 2 digits means "With Support" which special designed.

D. Purchase Parts Information;
- No puchase Parts
If you want to water flow test, φ2xID6 and φ3xID22 O-Rings are required.

E. Total Net Print Time: Approx. 43HR
- (Estimated as case of PLA, 0.4mm Nozzle, 0.2mm Layer Height, 40% infill and No raft and support)

F. 3D printing settings
Raft, Support, Layer Height, Infill: Depending on your experience.
For the parts having threads (Body and Cap): 0.2mm Layer Height recommended.
If you want to water flow test, 100% "In Fill" is recommended to reduce leaks.
My models were printed by "idbox" using with 0.4 nozzle, 1.75 PLA.

I do hope you enjoy making!!