Technical note | Development of a Fast Lumped Parameter Interior Ballistic Model for the Investigation of Novel Grain Geometry Performance

Abstract

The use of an Interior Ballistic model for gun system design allows the designer to evaluate the performance of propelling charges in an efficient manner. The implementation of a lumped parameter interior ballistic model that incorporates a number of grain geometry form functions for different propellant types is described in this report. The model has been developed for the testing of novel grain geometries that may be produced by non-conventional means, e.g. additive manufacturing. The code was required to have a fast run time, and be suitable for parametric optimisation to allow the performance of different grain geometries to be evaluated. The lumped parameter model provides a simplified simulation of the internal physical processes within the gun barrel. The time history of variables including the chamber pressure, chamber temperature, and projectile internal trajectories are calculated based upon a number of input parameters defining the gun system. The code also makes use of existing libraries for grain geometry form functions, enabling any additional grain geometry types to be shared with other existing tools. An example test case is also provided for validation purposes against another similar Interior Ballistic code.

Executive Summary

The use of an Interior Ballistic model for gun system design allows the designer to evaluate the performance of propelling charges in an efficient manner. The implementation of a lumped parameter interior ballistic model that incorporates a number of grain geometry form functions for different propellant types is described in this report. The model has been developed for the testing of novel grain geometries that may be produced by non-conventional means, e.g. additive manufacturing. These novel grain geometries have the potential to deliver significant increases in the performance of a gun system.

The code was required to have a fast run time, and be suitable for parametric optimisation to allow the performance of different grain geometries to be evaluated.

The lumped parameter model provides a simplified simulation of the internal physical processes within the gun barrel. The time history of variables including the chamber pressure, chamber temperature, and projectile internal trajectories are calculated based upon a number of input parameters defining the gun system. The code also makes use of existing libraries for grain geometry form functions, enabling any additional grain geometry types to be shared with other existing tools. An example test case is also provided for validation purposes against another similar Interior Ballistic code.

This code provides the ground work for analysing the performance of novel propellant grain geometries, and enables fast optimisation to be conducted to tune the dimensions of the propellant grain to suit a given gun system.