what is difference between 2D and 3D grain in rocket motor ?

Is there any difference in shape or something else?

1 Answer

2d grain is one where the cross sectional shape and area is the same from one end of the propellant to the other. The most common would have a star shaped internal profile that is extruded along the z-axis of the propellent. The profile is constant along the z-axis.

3d grain is such that the cross sectional shape and surface area changes from one end to the other. The profile changes along the z-axis.

The combustion and thrust performance of 2d shapes are easily modeled using manual methods. 3d shapes require much more complex computer analysis of the combustion and thrust profiles.