SIMULATION OF TURBOFAN ENGINE. PART 1. DESCRIPTION OF METHOD AND BALANCING TECHNIQUE

Abstract : The report describes a digital computer program titled SMOTE (simulation of Turbofan Engine). SMOTE is a computer program for balancing-cycle turbofan engines capable of running both design and off-design points. Component performance maps are reduced to Block Data (tabular form) to provide a base for calculating component performance. The design point is run first and map correction factors are calculated to scale the components to the desired performance. These correction factors are then applied to the component performance maps at off-design points. Initially, when the program is running at an off-design point, the cycle is not balanced, and errors (for example, work required by the compressor minus work supplied by the turbine) are generated. Small changes in engine independent variables (for example, compressor speed) then produce small changes in the errors, and these differential changes are loaded into a matrix. The matrix is then solved for the set of independent variables which results in zero errors, thus balancing the cycle. Actually, this process may be repeated several times before it reaches a balanced point because there is a non linear relationship between the independent variables and the errors. Sample results are included in the report.