Flameholding in Converging and Turning Channels over Cavities with Periodic Port Injection

Ben J. Colcord, William A. Sirignano, Feng Liu
2013 AIAA Journal  
The deliberate continuation of the combustion in the turbine passages of a gas-turbine engine has the potential to increase the efficiency and the specific thrust or power of current gas-turbine engines. This concept, known as a turbine burner, introduces certain challenges concerning the injection, mixing, ignition, and burning of fuel within a short residence time in a turbine passage characterized by large three-dimensional accelerations. Here, the injection of the fuel into a cavity
more » ... to a cavity adjacent to the modeled turbine passage is examined, which creates a low-speed zone for mixing and flameholding. The turbine passage is modeled as a converging and curving channel flow of high-temperature vitiated air adjacent to a cavity. To give a broader understanding of the cavity channel-flow coupling, both constant-area and converging channels with both straight and curving centerlines are modeled. Three-dimensional unsteady calculations with periodic port injection are performed, examining the effects of channel convergence and curvature, and injection configurations. These direct simulations address flows with Reynoldsnumber values up to 2000. Calculations show that converging channels reduce the combustion efficiency. Channel curvature can be either beneficial or detrimental to combustion efficiency, depending on the location of the cavity, and the fuel-and air-injection configuration. Injecting fuel and air so as to disrupt the natural rotation of the fluid in the cavity stimulates three-dimensional instability and improves the combustion efficiency.
doi:10.2514/1.j051890 fatcat:olohttrdfba6lllobq5ghlzys4