Radiation Pyrometer for Gas Turbine Blades.
Abstract:
The report describes the results of a program that has advanced the concepts and practical feasibility of radiation pyrometry for measuring the first stage blade temperature in gas turbine engines. Thermal radiation is accepted from the blades by sensor heads employing one of two different optical systems. The two sensor heads were designed to collect thermal radiation from either a spot or a reasonably large area of the turbine blade. High temperature fiber optics have been used to transmit the radiation to a remote detector housing, where the photons are converted into an electrical signal by a silicon photovoltaic cell. The current produced by the cell is routed to a signal processor which amplifies the signal, extracts one of three desired signal characteristics and then produces an output signal directly proportional to the temperature. This system measures and displays on a real time basis the average temperature of blades on a wheel, the average of the highest temperatures on a wheel, or the temperature of the hottest blade on the wheel. Both analog and digital signal information is available. System response is better than 10 msec in most cases. End to end system accuracy when calibrated with an electrically heated strip target was better than plus or minus 10F across the range of 1400 and 2200F. Author