Simulating the re-commissioning of the large bore gas gun
File(s)
Author(s)
Smith, Kirsty
Type
Thesis
Abstract
Following an incident, related to the fitting of incorrect recoil dampers, the Institute of Shock Physics gas gun required re-commissioning. It was decided that modelling predictions would be used to provide confidence in the safety of the system pre-experiment. A predictive method was developed and employed ANSYS simulations and numerical calculations. Using the failure scenario input conditions, the model indicated yield and failure of the bolts that secure the impact bracket.
A campaign of experiments, with increasing recoil momentum, were modelled and executed using the small gas chamber. Experimental results correlated well with modelling predictions, giving credence to the hypothesis that the original design was insufficient to mitigate the most demanding shots. Design changes were embodied to increase the damper total energy capacity and strengthen the fixing of the impact bracket to the supporting I-beam. Following these design changes, the large gas chamber was successfully re-commissioned, permitting safe operation of the gun throughout its original design specification. With the aid of mathematical simulation, a potentially catastrophic accident has been evaded and the Institute of Shock Physics gas gun has been safely re-commissioned for use.
With the gas gun back in operation, forecast experiments created a demand for an increased maximum velocity. As a side study, lightweight sabot solutions have therefore been explored. The investigation culminated in the launch of two designs, of which the extra short sabot, weighing 439g, was successful. The new maximum projectile velocity, using the small gas chamber at maximum pressure (69MPa) has been raised from 1,268m/s to 1,541m/s. If the shot were to be repeated using the large gas chamber, the projectile velocity would be expected to increase from 1,421m/s to 1,620m/s.
A campaign of experiments, with increasing recoil momentum, were modelled and executed using the small gas chamber. Experimental results correlated well with modelling predictions, giving credence to the hypothesis that the original design was insufficient to mitigate the most demanding shots. Design changes were embodied to increase the damper total energy capacity and strengthen the fixing of the impact bracket to the supporting I-beam. Following these design changes, the large gas chamber was successfully re-commissioned, permitting safe operation of the gun throughout its original design specification. With the aid of mathematical simulation, a potentially catastrophic accident has been evaded and the Institute of Shock Physics gas gun has been safely re-commissioned for use.
With the gas gun back in operation, forecast experiments created a demand for an increased maximum velocity. As a side study, lightweight sabot solutions have therefore been explored. The investigation culminated in the launch of two designs, of which the extra short sabot, weighing 439g, was successful. The new maximum projectile velocity, using the small gas chamber at maximum pressure (69MPa) has been raised from 1,268m/s to 1,541m/s. If the shot were to be repeated using the large gas chamber, the projectile velocity would be expected to increase from 1,421m/s to 1,620m/s.
Version
Open Access
Date Issued
2016-10
Date Awarded
2017-03
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Proud, William
Sponsor
AWE (Firm)
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Master of Philosophy (MPhil)