Browse Prior Art Database

Hot Start Protection with Adaptive Fuel Control Logic

IP.com Disclosure Number: IPCOM000245941D
Publication Date: 2016-Apr-19
Document File: 4 page(s) / 86K

Publishing Venue

The IP.com Prior Art Database

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 42% of the total text.

Page 01 of 4

Hot Start Protection with Adaptive Fuel Control Logic

Background:

    Exhaust gas temperature (EGT) of gas turbine engines are typically specified to be maintained within a predetermined range of temperatures to protect the gas turbine engine from damage. Gas turbine engines typically include an EGT sensor that monitors EGT and both alerts an operator that the EGT is outside the predetermined range and initiates protective logic sequences that automatically protects the gas turbine engine by lowering EGT. One such protective logic sequence may be implemented by a hot start protection and adaptive fuel control logic (herein after "hot start logic"). An instance when EGT can rise above the predetermined range of temperatures is during an in-flight start or hot start. In-flight starts occur when the gas turbine engine is restarted during flight or shortly after a shutdown. If the EGT exceeds the predetermined temperature threshold during a hot start, the hot start logic can prevent the engine from exceeding the EGT limit and damaging the engine.

    Previous hot start logic sequences reduced the fuel schedule, or the flow of fuel to the gas turbine engine, when EGT exceeded a predetermined range. The previous hot start logic sequences would continuously reduce and increase the fuel schedule in response to the EGT without ending the hot start logic sequence. The hot start logic and adaptive fuel control logic, in contrast to previous hot start logic sequences, increases the likelihood of a successful hot start by including logic that ends the sequence after a predetermined number of cycles and temporarily increasing the allowable EGT threshold.

Body:

    FIG. 1 is a logic diagram of hot start protection and adaptive fuel control logic. The hot start logic sequence begins when an in-flight start is commanded and the gas turbine engine did not successfully start and reach the idle operating mode. The hot start logic sequence shown in FIG. 1 is repeated approximately every 30 milliseconds until the gas turbine engine successfully starts and reaches the idle operating mode, unless the pilot aborts the start or the overall predetermined number of cycles the hot start logic is permitted to execute is reached. Hot start logic and adaptive fuel control logic consist of four main steps. The first step is the EGT check step which checks the temperature of the EGT and adjusts the fuel schedule accordingly. The


Page 02 of 4

second step is the engine speed check step which checks the speed of the gas turbine engine and adjusts the fuel schedule accordingly. The third step is the time/cycle check step which checks if the hot start logic and adaptive fuel control logic has exceeded a predetermined operating time or predetermined number of cycles and adjusts the predetermined EGT accordingly. The fourth step is the overall time/cycle check step which exits the logic sequence if the hot start logic and adaptive fuel control logic has exceeded a predetermined ove...