Oil-Free Turbocharger Demonstration Paves Way to Gas Turbine Engine Applications

Abstract

An oil-free, 150 Hp turbocharger was successfully operated to 100% speed (95,000 rpm), with turbine inlet temperatures to 650°C on a turbocharger gas test stand. Development of this high speed turbomachine included bearing and lubricant component development tests, rotor-bearing dynamic simulator qualification and gas stand tests of the assembled turbocharger. Self acting, compliant foil hydrodynamic air bearings capable of sustained operation at 650°C and maximum loads to 750 N were used in conjunction with a newly designed shaft and system center housing. Gas stand and simulator test results revealed stable bearing temperatures, low rotor vibrations, good shock tolerance and the ability of the rotor bearing system to sustain overspeed conditions to 121,500 rpm. Bearing component development tests demonstrated 100,000 start stop cycles at 650°C with a newly developed solid film lubricant coating. In a separate demonstration of a 100 mm compliant foil bearing, loads approaching 4,500 N were supported by a compliant foil bearing. This combination of component and integrated rotor-bearing system technology demonstrations addresses many of the issues associated with application of compliant foil bearings to gas turbine engines.

Micro Turbo-Fuel-Cell-Technology

“…The foil bearings technology has been improved continuously. Recently many research activities and demonstrations has been done worldwide in many branches of turbo machines, such as Turbochargers application (Heshmat, et al, 2006), Close Brayton's cycle turbine (Dellacorte, et al, 2005) and Rotorcraft Propulsion (Howard, et al, 2010). Once the air film is generated, the rotor is separated from the bearing surfaces which greatly reduce the power loss and ware of the bearings.…”

Analysis of the operating load of foil-air bearings in the gas generator of the turbine engine during the acceleration and deceleration maneuver

“…The technology of foil-air bearings was developed already in 1960 for high rotational speeds in designs of boosters for diesel engines, auxiliary power units for aircraft (APU) and selected sections of turbine engines [2,8,9]. Gas bearings can operate often where conventional oil-lubricated bearings cannot most often, because of their too high stiffness, too high rotational speed and thermal requirements [1].…”

“…claim that foil-air bearings are too risky if attempted to be implemented in new applications. Meanwhile, the researchers conducted a series of very extensive research to demonstrate their superiority over conventional bearings in many applications, especially for turbochargers and small oil-free gas turbines [8]. Besides, there are many methods to predict the lifetime of equipment, even if based the monitored diagnostic parameters.…”

Rotordynamic Performance Measurements of An Oil-Free Turbocharger Supported on Gas Foil Bearings and Their Comparisons to Floating Ring Bearings

“…For the TC, Howard [9] constructed a rotor design in 1999 to apply a foil bearing to the TC in diesel trucks. In 2000, Heshmat et al [10] applied foil bearings to a TC with 150 hp and conducted a drive test by raising the speed up to 120,000 rpm on the driving apparatus.…”