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Improving the Design and Evaluation of PDV-Based Cylinder Test Experiments for JWL-Parameter Determination

: Baust, Tobias Michael

Fulltext urn:nbn:de:0011-n-5968346 (5.0 MByte PDF)
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Created on: 22.7.2020

Propellants, explosives, pyrotechnics 45 (2020), No.9, pp.1344-1356
ISSN: 0340-7462
ISSN: 0721-3115
ISSN: 1521-4087
Journal Article, Electronic Publication
Fraunhofer ICT ()
PDV; Jones-Wilkins-Lee (JWL); Equation of state (EOS); cylinder test; simulation

The cylinder test experiment is an excellent method to derive Jones‐Wilkins‐Lee‐parameters as the expansion work of the detonation products can be determined from the experimentally observed wall velocity by an analytic approach. However, the physical description of the problem is essential for a precise determination of the expansion work. A useful method to develop and validate such models is to perform hydrodynamic simulations. This work aims to provide an improved analytic model and to introduce a robust and accurate solver design to calculate JWL‐parameters in combination with an optimization of the experimental setup. An extended version of an already accurate literature model is presented, where the air gap is taken into account within the balance equations. Moreover, the surface angle of the cylinder wall is determined from geometric considerations instead of preliminary simulations for conventional explosives. Besides, an own empiric approach for the strain model is introduced, which leads to a smaller deviation between the expansion work from the cylinder test simulation and the calculated expansion work for the underlying equation of state. Regarding the derivation of JWL‐parameters and the determination of the Chapman‐Jouguet‐pressure, the complete workflow, including the global numerical optimization method, is described in detail and the accuracy and robustness of the solver are proven. The entire workflow is validated for different (full‐wall) geometries and conventional explosives to verify that the method scales. Finally, geometric considerations for the placement of the PDV‐gauges are provided to optimize the design and geometry of cylinder test experiments.