Critical ignition conditions of TiAl alloy under simulated compressor conditions

To extend the engineering applications of TiAl alloy in hot-section components of high-pressure compressors, it is essential to clarify its ignition boundaries under realistic service conditions. Focusing on the flammability of TiAl alloy under compressor conditions, the surface oxidation reaction rate of TiAl is obtained using both experimental energy balance analysis method and first-principles approach combined with thermodynamic statistics. The effects of incoming flow velocity, temperature, pressure, and angle of attack on the thermal autoignition of TiAl alloy are investigated via numerical simulation. The critical external energy density required for forced ignition under typical multistage compressor design-point conditions is also determined. Results show that although increased pressure promotes surface oxidation, it concurrently enhances convective heat transfer, thereby raising the critical incoming flow temperature for autoignition. At high angles of attack, flow separation significantly reduces heat transfer efficiency, leading to a lower critical autoignition temperature. Under typical simulated conditions of a multi-stage compressor, TiAl alloy does not spontaneously ignite without external energy. However, when the external energy density reaches the thermal levels corresponding to faults such as blade tip friction, there is a risk of forced ignition.