Jun Hosoi

Bluff Body Flame Holder with Flow Entrainment Using Perforated Plate

Benefits of flow entrainment in bluff bodies to control stagnation pressure losses are investigated. Bluff bodies yield stagnation pressure loss due to flow recirculation and sudden expansion flow for flame holding. A portion of incoming unburned flow is entrained through a perforated plate and directly introduced to a low velocity region. The velocity gap at the trailing edge of bluff bodies is mitigated in order to reduce the stagnation pressure loss. Flow diffusion in a short distance is one of the main challenges of this concept. This challenge is addressed by scaling down the size of entrained jets. The proposed configuration is first characterized in control volume analysis. The mitigation of the loss generation is remarkable under the condition with the high blockage ratio of bluff bodies. The further details accounting for the three-dimensional complexities are next investigated using numerical simulation and the system feasibility is demonstrated. The capability of flame holding is also examined in a combustion experiment using a single bluff body. Preheated and high speed air demonstrating the environment of a real combustion chamber is supplied to the apparatus. It is successfully found that the proposed concept is not only beneficial to control the stagnation pressure loss, but also to extend the blow off limit.