Mesh refinement box on a combustion chamber geometry

Hello everyone

I am dealing with the meshing of a combustion chamber in salome. Basically the chamber is just like a rectangular box in which air and fuel enter through a hole made in one of the faces and start reacting. I would like to carry a refinement of the mesh in the flame zone of the combustion chamber. Therefore, I would like to find a tool allowing me to design a geometrical box (like a cube or a rectangle) in which the 3D mesh must be refined. However, I dont find any tool allowing me to do that in the mesh module.

I have thought of modifying the geometry to reach my goal but I guess there might be some easier way directely in the mesh module of Salome to do such a basic thing ?

Would you have any ideas to perform such an operation ?

Thanks in advance