Method of determining most extreme operating parameters for gas turbines
Publication Date: 2016-Mar-02
The IP.com Prior Art Database
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Method of determining most extreme operating parameters for gas turbines Background:
During the processes of designing and rating gas turbine engines, the most extreme operating conditions that the engine will experience must be assessed. The most extreme parameters to be studied may include various temperatures, pressures, flow rates, rotor speeds and shaft torques, among other properties. These quantified levels are used to aid the design of the engine components. However, at least some of these methods for performing such calculations are formulated for applications where the engine is controlled to maintain the delivery of a specific power or thrust level. (An example of these methods can be found in Reference 1.) Accordingly, these previous methods may not be well suited for other gas turbine implementations, where various control limits are imposed to limit the engine output and extend the lifespan of the engine. In certain cases using these previous calculation methods, when the interaction of these control limits is not accounted for, the calculated values of extreme parameters may be higher than is realistic. Applying these higher values as design criteria may result in an overly conservative design, which can reduce the overall system performance, increase engine weight, and increase product cost. There is therefore a need for an alternative method to determine the most extreme operating parameters for gas turbines with interacting control limits.
Described herein is a new method for more accurately predicting the most extreme operating parameters of gas turbine engines with interacting control limits. The method employs a system model, applied using a combination of techniques. In particular, the method includes first determining a power level and operating envelope for the gas turbine to be analyzed. The operating envelope sets the boundary conditions for parameters such as ambient temperature, ambient pressure, and vehicle velocity. The method also includes identifying factors that can affect engine performance. These factors may include, for example, ambient humidity, installation losses, fuel type, fuel lower heating value, unique control operating modes, engine offtakes, engine-to-engine manufacturing variation and/or deterioration level, among others. The
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next step in the method is to identify expected extreme values of each of those factors. Such identification may be made based on empirical values, predicted values, and/or a combination thereof.
Next, for a particular parameter of interest (e.g., turbine inlet temperature), a matrix of points within the operating envelope is generated. In previous methods, a matrix of points generated for modelling is generally limited to the power level and ambient conditions within an operating envelope. In the present method, the matrix of points is expanded to encompass the variation of many or all of the above-identified factors within the operating enve...