Learning Forum

[Hagi Nilaathan Subramaniam]

hey,

im trying to simulate the chemical kinetics of rotating detonation engine using Pasr reactor in chemkin. these are inlet conditions given in literature

            fuel and oxidizer inlet temperature = 300k

            fuel and oxidizer inlet pressure = 3atm

in rde they use an ignitor called pre detonator, which has exhaust temperature and pressure of 2500k and 50bar.

How to configure the ignitor setup in chemkin?????

*** I tried a preheated a preheated fuel and air configuration but in result the pressure remains constant. ****

[jcooper]

Hi:

There probably isn't an easy equivalent here....  The reaction rate is likely pressure and temperature-dependent. So, you could use the same Chemkin mechanism in Fluent with the partially premixed combustion model and mimic the geometry of the flow channel for the premixed mixture.   It is the detonation and high speed expansion of the gas that drives the flow and gets the pressure from 5 atm to around 50 atm, so you would have to get the geometry and mesh/modelling just right to get the same pressure rise.

Below are some typical model choices in Fluent for capturing these types of flows.  (I would suggest reading up on the partially premixed combustion model --which can also handle premixed mixtures-- and the role of the progress variable in ignition.  Because of the high speed of the flow, you will probably need an advanced turbulence model and fine mesh to capture the hydrodynamics here.  If the flow is highly supersonic (> Mach 4.0), you may have to move to the density-based solver.

Realizable K-Epsilon; LES
• Partially premixed combustion model
– Turbulent flame speed = Laminar flame speed = 0.623
– Default or source term to progress variable
• Flame area density: Bogers’ model (UDF)
• Coupled PBNS (Pressure based coupled solver only to Mach 4.0)
• PRESTO!
• Bounded second order time discretization
• Second order for all variable except turbulence
• Ignition Source
– 6 mm diameter sphere
– Progress variable = 1 in center and zero at periphery
• Boundary conditions
– Adiabatic Wall
– Pressure outlet: T= 293k, P = 47 kPa