SafeDDT – Deflagration to Detonation Transition
Dimensioning of pipes to withstand the deflagration to detonation transition for the safe transport of premixed explosive gases
The new research project SafeDDT started in April 2019 and deals with the numerical design of pipes for the transport of premixed explosive gases, considering DDT. In case of an unwanted ignition, there is the possibility of a combustion, which starts as deflagration and changes into a detonation. This change is called DDT – Deflagration to Detonation Transition. So far, the states of detonation are well known, here it is possible to calculate the maximum pressure of detonation (CJ-pressure) using Chapman-Jouguet conditions. It is proven by experiments that the maximum pressure at the time of DDT (DDT-pressure) exceeds the CJ-pressure multiple times. The current method considering DDT in the dimensioning of pipes relies on experimental tests, which are associated with high financial and time costs.
The aim of the research project is to develop a design method based on numerical models, which guarantees the safe design of pipes under consideration of DDT. Using reactive CFD simulation, the combustion of premixed explosive gases in pipes from ignition to detonation is to be modeled. As a result of the CFD simulation, a function of pressure, including the maximum pressure at the time of DDT, is determined as a function of time, location and initial conditions. The function of pressure is the basis of an FE simulation for the calculation of the maximum stress for the dimensioning of the pipe. The numerical models developed for CFD and FE simulation are validated by experimental tests. A parameter study is then performed with the validated models and selected initial conditions.
Winstainforth [CC BY-SA 3.0], via Wikimedia Commons