KNSU Propellant Grain Geometries

There are two types of Solid Rocket Motors (SRMs): endburners and coreburners. The type of SRMs investigated in this project are coreburners, which burn from the inside of the propellant grain to the motor’s inner wall. The cross-sectional area of the propellant grain is known as grain geometry, and the simplest shape is a circle. This means the burning surface area is the circle’s circumference. As the circle burns outward, the circle’s circumference expands, increasing the propellant’s burning surface area. The thrust is therefore proportional to the propellant’s exposed surface area. This exposed surface area dictates a SRM’s performance and can be utilized to achieve the desired thrust curve. Historically, in order to change the thrust curve, the cross-sectional area is adjusted by changing the geometry. The purpose of this project is to compare the thrust and pressure curves of different propellant grain geometries with a sucrose fuel and potassium nitrate oxidizer (KNSU). Due to manufacturing considerations, the initial tests will be conducted with circular grains. All circle grains burn progressively, since the surface area increases during the burn. However, if a grain’s geometry is designed without increasing surface area, then the SRM’s thrust and pressure curves will be more uniform. In order to examine this, a star shaped cross-sectional grain geometry with an equal volume to the circular grain will be tested. This comparison will demonstrate the regression, thrust, and pressure properties of KNSU propellant, and provide data to be used for comparison of different propellant grain geometries. Ignite Grant Awar