Description

Combustion

The assumption for Combustion Chamber CFD Simulation

There are several assumptions to solve the Combustion Chamber CFD Simulation:

1. The simulation is transient
2. The flow is Incompressible; hence, the solution is pressure-based.
3. We consider the effect of Earth’s gravity on problem-solving.

Combustion Chamber CFD Simulation Procedure

Step 1: Geometry

The geometry of the present model is 3-D and Design Modeler software designs it. Inside the combustion chamber, there are three main parts, including the air inlet pipe, the burner section, and the outlet pipe. Inside the chamber, there is a thin wall with several cavities of varying dimensions. The primary small cavities for cooling the chamber wall by layering flow and the next big ones are to keep the flame in the middle of the chamber.

Step 2: Mesh

ANSYS Meshing software performs the meshing of the present model. The mesh type is unstructured. We use a triangular grid and the element number is 694928.

Step 3: Set-Up

Here is a summary of the steps to define and solve the problem in the table:

(Model)

Turbulence

k-epsilone

مدل k-epsilon

RNG

رفتار نزدیک دیواره

Standard wall function

species transport

Defined Species

O2 , CO , CO2 , CH4 , N2 , H2O (vapor)

Energy Equation

on

(boundry conditions) for combustion simulation

Inlet

mass flow inlet

Combustion Simulation

Inlet Air

Mass Flow

0.02 kg.s-1

Temperature

300 K

O2 mass fraction

0.23

N2 mass fraction

0.77

Inlet Fuel

mass flow

0.0006 m.s-1

temperature

300 K

CH4 mass fraction

1

O2 mass fraction

0

N2 mass fraction

0

Outlet

Pressure outlet

Outlet Air

Relative Pressure

0 Pa

O2 mass fraction

0.23

N2 mass fraction

0

Wall B.C

Wall

Heat Flux

0 (isolated)

Diffuse

zero

Methods for combustion simulation

Coupled

Discretization

momentum

Second order upwind

pressure

Second order upwind

energy

Second order upwind

species transport

Second order upwind

Turbulence kinetic energy equations

First order upwind

Turbulence Waste Rate Equations

First order upwind

initialization for combustion simulation

Standard

temp

300 K

O2

0.23

Species

0

We apply the Standard Wall Function and K-epsilon RNG model for the turbulence equation, since the flow inside the combustion chamber is relatively complex and the simulation is steady. We use the species Transport model and the species are O₂, CO, CO₂, CH₄, N₂, H₂O (vapor) for this simulation.

in this case, there are two steps for the reaction of methane burning with oxygen, with six species involved in the reaction, namely: methane, Oxygen, nitrogen, water vapor, carbon dioxide, and carbon monoxide. The air mass flow inlet is 0.02 kg.s^-1  and inlet air temperature is equal to 300 k. Mass fractions are .23 and .77 for oxygen and nitrogen, respectively. The fuel is methane and its inlet temperature is 300 k, also the flow rate is 0.0006 m.s^-1. Ultimately, the walls are insulated and the solver method is coupled.

 

All files, including Geometry, Mesh, Case & Data, are available in Simulation File. By the way, Training File presents how to solve the problem and extract all desired results.