Tutorial 04

Use injector sizing tools.

Define injector assumptions, solve the case, and read the geometry-implied O/F, pressure-drop, and packing checks.

What you will learn

How to set injector pattern, discharge coefficients, hole counts, desired diameters, jet angles, impingement distance, injector L/D, and face diameter.

Prerequisites

Set propellants, mixture ratio, chamber target, and sizing basis. Use Injector geometry sizing basis when geometry should drive the engine size.

Steps

Open Define > Hardware, then select the Injector sub-tab.
In Injector inputs, choose Unlike doublet, O-F-O triplet, F-O-F triplet, or Showerhead.
Enter Ox Cd (discharge coeff.) and Fuel Cd (discharge coeff.). Different stream Cd values are supported and are checked during solve.
Set Ox hole count and Fuel hole count. For unlike doublets, counts are usually equal; triplets intentionally differ by pattern.
Enter Desired ox hole diameter and Desired fuel hole diameter, then set Ox jet angle to axis (deg), Fuel jet angle to axis (deg), and Impingement distance.
Set Injector L/D. Enter Injector face diameter, or use 0 to derive it automatically from chamber diameter x 0.90.
Click Solve, then open Review > Injector. Read momentum ratio, face packing fraction, element pitch, spray angle, per-stream sizing, and warnings.

Injector inputs and solved injector review outputs — Injector inputs and solved injector review.

Expected result

The solved injector review reports the selected pattern, stream sizing, packing checks, momentum ratio, and any injector Delta P/Pc stability warnings.

Common notes

In Injector geometry sizing mode, the geometry-implied O/F can differ from the target O/F. Review the effective mixture ratio before using the result.
Warnings below about 15 percent injector Delta P/Pc flag feed-coupling risk; high pressure drop warns about elevated feed pressure.
The injector tool is a sizing and screening workflow; detailed combustion stability still requires qualified review and test correlation.