The manual fuel flow control component enables direct specification of off-design fuel flow to a combustor component (design fuel flow is specified in the combustor component). This component is the simplest for specifying power setting of a gas turbine engine model, disregarding any control system logic. Usually the manual fuel flow control is used for steady state off-design engine performance calculations, either single off-design points or steady state series parameter sweeps using the input table (numeric grid) to define a range of fuel flows.

The manual fuel flow control can also be used to calculate transient responses on fuel flow variations. An example would be the calculation on fuel flow step responses for control system design (using system identification techniques?). The fuel flow step functions then are specified in the transient input table.

The manual fuel control Specify option settings are similar to those in the combustor component linked to it. However, the selected option in the combustor may be different from that in the manual fuel flow control, to facilitate different ways to specify power setting DP and OD.

Note that

Note that upon selecting SOT input, an equation needs to be added, so a reset of the model and recalculation of the DP is required. SOT is evaluated in an error equation (with Wf as state) in the iteration towards user specified SOT (iteration necessary because SOT may be affected by downstream HPT cooling flows).

Fuel flow also can be specified as a 'free state' in order to calculate an off-design operating point with (instead of user specified fuel flow Wf, combustor exit temp. or fuel-air ratio) an alternative user specified power setting condition such as turbine rotor speed and/or power load ('Power balance at rotor speed' turbine component model option). Using the Fuel flow as a free state model option always requires the setting of another component's option to provide an extra error variable to maintain an equal number of model state and error variables. If this requirement is not met (no corresponding settings in two components), a 'Model configuration inconsistent' (Nstates<>Nerrors) error is reported.

The checkbox Always create state specifies whether the state is added to the equation system. This advanced option is usually set by other components when configuring the model.