There may be errors with powder burn model in ANSYS-Autodyn.

- February 28, 2023 at 1:45 am
  
  Bi Shengfan
  Subscriber
  
  I have a problem with the material model in Autodyn. The gas pressure calculated by the Powder burn (beta) maybe incorrect. Input of the material data is in accordance with the user guide provided by Autodyn(Autodyn 2022). I chose a slow-burning particle for one cell test, and compare the results obtained by Autodyn with the theoretical results. The theoretical results are solved directly by the Runge-Kutta methods. The comparison of pressure curves is in the attachment.
  
  The results show that pressure calculated by Autodyn rises faster. Some scholars also found the problem in their paper published in 2020 (Fikus and Michalski 2020). The noticeable difference between results obtained with Autodyn model and experimental data is visible in the rise time of the pressure. In the case of the commercial code, this time is significantly shorter, which can be a result of specific way of modeling of reaction effects.
  
  https://www.researchgate.net/publication/348025699_ASSESSMENT_OF_APPLICABILITY_OF_ANSYS_AUTODYN_POWDER_BURN_MATERIAL_MODEL_TO_COMBUSTION_CALCULATIONS_IN_CONDITIONS_OF_INTERNAL_BALLISTICS?_sg=otNkmskyeOp0RmrC3EZeXmd3cmU6ChzYm22vrcIaM4JWShrKRq3woZQk2zkVAEhDJX9KbipRtQ-QTNA
  
  In order to verify the error of Autodyn, I do a back calculation. The derived variable results in Autodyn are used to calculate the parameter relationships in the model. It is found that the corresponding relationship between burning rate and gas density is correct. However, when exponential gas EOS is adopted, the corresponding relationship between gas pressure and gas density is not valid. The question is what the PRESSURE variable actually represents. Is it effective pressure? It is possible that Pressure and GAS.Pressure are reversed in the software programming.
  
  Because this model may have errors, some researchers must develop their own subroutines. I want to talk to software developers to check for errors in the model. I am willing to help in any way I can.
  
  If you have any ideas, please contact bsf@njust.edu.cn.
  
  Autodyn, A. (2022). "AUTODYN User’s Manual." ANSYS Inc.
  
  Fikus, B. and J. Michalski (2020). ASSESSMENT OF APPLICABILITY OF ANSYS AUTODYN POWDER BURN MATERIAL MODEL TO COMBUSTION CALCULATIONS IN CONDITIONS OF INTERNAL BALLISTICS.