Ceramic Engine Components Under Commercial Production

In the field of diesel engine components, ceramic glow plugs assisting quick start up of chamber diesel engines had been developed in September, 1981 and ceramic swirl chambers followed in commercialization in April, 1983. These ceramic components are currently under commercial production and are installed on passenger cars on the merket. Silicon nitride (Si3N4) is the material of these components, and a lot of mass-production technique has firmly established in order to achieve competitive price and high durability in comparison with the conventional metal components. Because of its excellent heating characteristics, ceramic glow plugs have eliminated the “waiting time” before the start-up of diesel engines. As the result, drivers can enjoy quick starting of engines as they can do with gasoline fueled vehicles. Ceramic swirl chambers could drastically reduce idling noise of diesel engines and remarkably improved starting performance in the cold climate operation.

Stress Mapping of a Low Pressure Compressor for an Advanced Turbojet Engine

Vibratory stress characteristics of the low pressure compressor in the Pratt & Whitney Aircraft PW1120 turbojet engine recently have been evaluated during full-scale engine testing at the United States Air Force’s Arnold Engineering Development Center. A description is presented of the approach used to evaluate the vibratory characteristics of the new three stage low pressure compressor. Results are presented showing the effects of simulated altitude conditions, inlet pressure distortion, and off-schedule variable vane operation. Strain gage data is compared to case-mounted light probe data, and the levels of system damping and mistuning are discussed. Predicted vibratory response is compared to test results showing the new compressor to be free of destructive vibration.

Corrosion and Corrosion Control in Gas Turbines: Part I — The Compressor Section

Corrosion processes in the compressor and turbine section of a gas turbine are basically different and are treated separately. The subject of this first paper is the compressor section. Firstly, the conditions controlling the corrosion behaviour in the compressor are considered. Next the different forms of corrosion in compressors and the various methods to combat these corrosion processes are considered. Special attention is paid to: •rinsing and washing •the properties of protective coatings with regard to corrosion and erosion. Corrosion processes in the turbine section are discussed in part II.

A New Gas Turbine Combustor Alloy

A wrought, nickel-base superalloy based on the Ni-Cr-W system has been developed for applications in the hot section of gas turbine engines. The new alloy is solid solution strengthened and very thermally stable. It particularly resists the formation of detrimental intermetallic compounds and contains little or no cobalt. Various mechanical and oxidation properties of the new alloy were measured, and the microstructural features were characterized. These were compared with those for other solid solution strengthened, high-temperature alloys. A number of advantages of the new alloy are defined.

Measurements of Squeeze Film Bearing Forces to Demonstrate the Effect of Fluid Inertia

Squeeze film dampers are commonly applied to high speed rotating machinery, such as aircraft engines, to reduce vibration problems. The theory of hydrodynamic lubrication has been used for the design and modeling of dampers in rotor dynamic systems despite typical modified Reynolds numbers in applications between ten and fifty. Lubrication theory is strictly valid for Reynolds numbers much less than one, which means that fluid viscous forces are much greater than inertia forces. Theoretical papers which account for fluid inertia in squeeze films have predicted large discrepancies from lubrication theory, but these results have not found wide acceptance by workers in the gas turbine industry. Recently, experimental results on the behavior of rotor dynamic systems have been reported which strongly support the existence of large fluid inertia forces. In the present paper direct measurements of damper forces are presented for the first time. Reynolds numbers up to ten are obtained at eccentricity ratios 0.2 and 0.5. Lubrication theory underpredicts the measured forces by up to a factor of two (100% error). Qualitative agreement is found with predictions of earlier improved theories which include fluid inertia forces.

Operating Experience With a 13,000 SHP, Two Stage, Fluid Cat-Cracker Power Recovery Expander

An internal inspection of the expander after 16,000 hours of operation confirmed the successful operation of Ingersoll-Rand’s first two stage, high temperature, FCC expander. This paper discusses the construction and operation of the unit, designed for 1300°F (704°C) dirty gas environment and presents the inspection results of critical components.

FCCU Power Recovery With Gas Turbine Systems

This paper pertains specifically to refinery fluid catalytic cracking and associated power-recovery concepts. The several systems described go beyond basic onsite FCC practices previously used. However, no special technical development or prototypes would be required to engineer practical and successful installations. All component equipment and apparatus reflect current state-of-the-art, requiring only explicit economic justification. The individual systems, as presented, are solely conceptual, but sufficient detail is provided to confirm their technical feasibility. Application economics will depend on geographic location, site conditions and the specific process installation.

Aeronautical Propulsion: Present Status and Future Directions

The advancement of aeropropulsion systems continues to provide technology to various portions of the gas turbine field. It is recognized that this area is undergoing considerable change, which will result in substantially improved gas turbine components and systems. These changes are occurring in a number of technical areas including advanced analytical and physical measurement methods, the application of large scientific computers, the dynamic modeling of components and systems, the application of integrated control systems that optimize and improve performance and system condition monitoring, and the development of new and unique materials and structures. As these areas evolve, the ways in which technology will advance, and factors affecting the design and development of new systems, will probably be considerably different than those of today. It is also anticipated that the necessary skilled work force will be different. Certainly there will be changes, but the nature, extent, and rate of those changes can only be surmised at this time.

Turbotest: A Computer Program for Rig Test Analysis of Arbitrary Gas Turbine Engines

This paper presents a computer model called ‘TURBOTEST’ which is applicable both to analysis of gas turbine engine rig tests and to simulation of engine steady-state performance. As with the earlier ‘TURBOFLEXI’ model a wide range of gas turbine engines can be simulated, using any kind of hydrocarbon fuel, and allowing for chemical dissociation of the gas, and for the effect of air humidity. In addition, however, for the particular requirements of rig test analysis, the following new features have been developed and incorporate:- (a) It can carry out rig test analysis for a wide range of gas turbine engines if all the necessary test data are presented. (b) If the test data is incomplete, a computer simulation of the engine can be used to complete the analysis. (c) Performance deterioration of engine components can be detected by comparing the results of a test analysis and of a parallel simulation using stored characteristics of engine components in the “as new” condition. The program has been tested on simulated test data generated by engine models such as a turbojet and a turbofan. The results show it has close and repeatable agreement with design values. Further tests of the model have been carried out by applying it to the actual engine rig test data.

Aeroelastic Instabilities in Labyrinth Air Seal Systems

An analysis is developed that can be used to calculate the aeroelastic instabilities of labyrinth air seal systems. The formulation considers both the stator and rotor as flexible components and the fluid within the cavity has both axial and swirl components of velocity. The interaction of the leakage flow (through the clearance between lips of the seal and the stator) with the vibratory modes of the rotor and stator provides the mechanism for possible aeroelastic instability. A limited parametric study shows that increasing the stiffness of either the rotor or the stator has the same stabilizing influence as including, in the analysis, swirl flow component of the leakage flow. Further, at frequencies where coincidence between stator and rotor modes occurs, there could be a sharp drop in available aerodynamic damping. These results, which need experimental confirmation, can influence the design of these important components of jet engines.