GSP models > Equations

GSP calculates engine performance and gas condition changes across the components using the following equations:

•equations for conservation of mass

•equations for conservation of energy

•the perfect gas state equation

•the isentropic flow equation

•equations for conservation of momentum of gas flow

•the equation for rotor inertia effects

•equations for heat flux between the gas path, material and ambient environment.

From these equations, a set of non-linear differential equations (NDEs) is arranged and solved by the GSP solver. Since gas turbine off-design models are particularly non-linear, customary solvers often fail to converge. Therefore GSP has it's own Newton-Raphson based solver optimized for gas turbine models. The model operating point is defined by a number of states (or 'free states') collected in a state vector. The number of NDEs equals the number of states and the deviation from a valid solution is represented by the error vector which holds the error values. The GSP solver iterates towards the solution where all errors are zero (within the user specified tolerance).