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Experimental investigation of an overriding control to effect recovery from surge and stall in a turbojet engine

Description: The override was designed to automatically recover the engine from stall and surge by reducing fuel flow and then increasing fuel flow in a manner to avoid repeated stalls and surges and successfully complete the acceleration. One of two parameters was used to operate the override, tailpipe temperature, or the derivative of compressor-discharge pressure. The override operating with tailpipe temperature recovered the engine from stall and surge. Operating on compressor-discharge-pressure derivative, the override recovered the engine from surge, but failed when stall was encountered.
Date: October 29, 1956
Creator: Stiglic, Paul M. & Heppler, Herbert
Partner: UNT Libraries Government Documents Department

Experimental and analytical investigation of an acceleration regulating control for a turbojet engine

Description: Report presenting an acceleration control that operates on fuel flow and uses directly measured acceleration as the control signal as applied to an axial-flow turbojet engine. A study to determine the feasibility and dynamic characteristics of the control was undertaken. Results regarding the open-loop characteristics and closed-loop characteristics are provided.
Date: June 28, 1956
Creator: Stiglic, Paul M.; Heppler, Herbert & Novik, David
Partner: UNT Libraries Government Documents Department

Experimental investigation of acceleration characteristics of a turbojet engine including regions of surge and stall for control applications

Description: The acceleration characteristics, in the region of maximum acceleration and compressor stall and surge, of an axial-flow turbojet engine with a fixed-area exhaust nozzle were determined by subjecting the engine to fuel flow steps, ramps, and ramps with a sine wave superimposed. From the data obtained, the effectiveness of an optimalizer type of control for this engine was evaluated. At all speeds above 40 percent of rated, a maximum acceleration was not obtained until the engine reached the point of stall or surge. A sharp drop, as high as 80 percent of maximum, in acceleration then occurred as the compressor entered surge of stall. With the maximum acceleration occurring at the point of surge or stall, the optimalizer-type control could not prevent the engine from entering surge or stall. Effective operation of the control may still be possible by sensing the sharp drop in acceleration experienced at the point of stall or surge and using this signal to limit fuel flow. The success of this type of operation would depend on the magnitude of the stall-recovery hysteresis.
Date: December 20, 1954
Creator: Stiglic, Paul M.; Schmidt, Ross D. & Delio, Gene J.
Partner: UNT Libraries Government Documents Department

Experimental investigation of a surge control on a turbojet engine

Description: The action of a surge control that reduced fuel flow after receiving an indication of surge initiation was investigated. The control system could successfully limit surge to only 1 cycle but could not completely eliminate surge. Inability to interrupt a surge cycle before its completion was attributed to the conclusion that a surge cycle is irreversible.
Date: November 18, 1955
Creator: Novik, David; Heppler, Herbert & Stiglic, Paul M.
Partner: UNT Libraries Government Documents Department

Analytical and experimental investigation of a temperature-schedule acceleration control for a turbojet engine

Description: From Introduction: "This report investigates some of the problems involved in scheduling the tailpipe temperature to avoid stall during acceleration. The object of this report is to investigate the dynamics of a closed-loop acceleration control that follows a schedule of tailpipe temperature with rotor speed."
Date: June 22, 1958
Creator: Heppler, Herbert; Stiglic, Paul M. & Novik, David
Partner: UNT Libraries Government Documents Department