Fire Hazard Assessment of Typical Flammable Liquid Oils in Wind Turbine Nacelle

Abstract

To assess fire hazards of gearbox oil and transformer oil applied in the nacelle of a wind turbine, the reaction-to-fire properties prior to combustion should be addressed. Gearbox oil and transformer oil were studied by using cone calorimeter exposed to external radiant heat flux levels of 15, 25, 35, 50, and 75 kW/m2. Potential fire scenarios in which liquid oils contribute to the fire spread areas and fire intensities were designed and proposed. The reaction-to-fire properties of such oils are researched from two aspects of thermal hazard and nonthermal hazard. And the critical thermal radiant flux \( (q_{\text{cr}}^{{\prime \prime }} ) \) and the time of ignition \( (t_{\text{ig}} ) \) were obtained by the conical calorimeter, and the ignition characteristic was analyzed. Results show that based on the analysis of PKHRR and THR, the reaction of fire properties of the transformer oil is higher than gearbox oil, and based on the analysis of PKSEA, PKRSR, and TER, the gearbox oil is higher than transformer oil. In the same radiant heat flux, based on PKHRR and THR to determine the liquid oil fire hazard rankings are: transformer oil > gearbox oil; based on PKSEA and TSR to determine the fire hazard ranking are: gearbox oil > transformer oil. The critical radiant heat flux of gearbox oil and transformer oil is 9.23 and 6.43 kW/m2 when the radiant heat flux is 15 kW/m2. The same liquid oils have the least ignition time and the larger fire hazards when the radiant heat flux is 75 kW/m2.