Observed Rotordynamic Phenomena in Aircraft Gas Turbine Development

2015 ◽  
Author(s):  
Fredric F. Ehrich
Keyword(s):  
Gas Turbine ◽  
High Speed ◽  
Nonlinear Effects ◽  
Aircraft Engine ◽  
Tip Clearance ◽  
Resonant Peak ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Nonlinear Responses ◽  
Remedial Actions

Observations, analysis and understanding of out-of-the-ordinary rotordynamic phenomena (including several instabilities and nonlinear responses) observed in aircraft gas turbine engines and other high-speed rotating machinery over the course of the author’s career in the design and development of aircraft gas turbine engines are described. Some observed phenomena were already widely recognized in the rotordynamic community such as: • Hysteretic whirl • The tip clearance effect on stability of turbomachinery rotors • Instability due to trapped liquids in the rotor • Hysteresis in the resonant peak amplitude • Effective suppression of rotor instability by anisotropy in the engine support structure Other observations were fairly new to the field of rotordynamics at that time they were observed but were identified as being new manifestations of vibration phenomena already familiar to vibration technologists in fields other than high-speed rotordynamics such as: • Sum-and-difference frequency response • Relaxation oscillations • Nonlinear effects of anisotropic clearance in roller and gas bearings At that time these phenomena were observed, the pressure for remediation of the problems they represented in the context of ongoing aircraft engine development resulted in intense attention and analysis which, in turn, often resulted in new insights, useful diagnoses, and effective remedial actions.

Renovation features of powder high-speed steels broaches with plazma hardening

2021 ◽  
pp. 82-85
Author(s):  
A.S. Politov ◽  
R.R. Latypov
Keyword(s):  
Gas Turbine ◽  
Comparative Studies ◽  
High Speed ◽  
Atmospheric Plasma ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Cold Atmospheric Plasma ◽  
Plasma Hardening

The comparative studies results of the durability of cutting properties of new and restored by regrinding and repeated plasma hardening with the application of multi-layer Si—O—C—N nanocoating system (PECVD by cold atmospheric plasma) powder high — speed steels broaches teeth for the processing of hard-to-process materials profilecomposite gas-turbine engines components are presented.

Practical Implications of Integrating Turbomachinery Into the Air Turborocket

2004 ◽  
Author(s):  
Joshua A. Clough ◽  
Mark J. Lewis
Keyword(s):  
Gas Turbine ◽  
Aircraft Engine ◽  
Launch Vehicle ◽  
Turbine Engines ◽  
Inlet Temperature ◽  
Gas Turbine Engines ◽  
Turbine Inlet Temperature ◽  
Turbine Engine ◽  
Space Launch ◽  
Practical Implications

The development of new reusable space launch vehicle concepts has lead to the need for more advanced engine cycles. Many two-stage vehicle concepts rely on advanced gas turbine engines that can propel the first stage of the launch vehicle from a runway up to Mach 5 or faster. One prospective engine for these vehicles is the Air Turborocket (ATR). The ATR is an innovative aircraft engine flowpath that is intended to extend the operating range of a conventional gas turbine engine. This is done by moving the turbine out of the core engine flow, alleviating the traditional limit on the turbine inlet temperature. This paper presents the analysis of an ATR engine for a reusable space launch vehicle and some of the practical problems that will be encountered in the development of this engine.

scholarly journals Advanced Technology for Reducing Aircraft Engine Pollution

1974 ◽  
Vol 96 (4) ◽  
pp. 1354-1360 ◽  
Author(s):  
R. E. Jones
Keyword(s):  
Gas Turbine ◽  
Aircraft Engine ◽  
Advanced Technology ◽  
Turbine Engines ◽  
Variable Geometry ◽  
Gas Turbine Engines ◽  
Large Reduction ◽  
Final Phase ◽  
Fuel Staging ◽  
Develop Technology

The proposed EPA regulations covering emissions of gas turbine engines will require extensive combustor development. The NASA is working to develop technology to meet these goals through a wide variety of combustor research programs conducted in-house, by contract, and by university grant. In-house efforts using the swirl-can modular combustor have demonstrated sizable reduction in NOx emission levels. Testing to reduce idle pollutants has included the modification of duplex fuel nozzles to air-assisted nozzles and an exploration of the potential improvements possible with combustors using fuel staging and variable geometry. The Experimental Clean Combustor Program, a large contracted effort, is devoted to the testing and development of combustor concepts designed to achieve a large reduction in the levels of all emissions. This effort is planned to be conducted in three phases with the final phase to be an engine demonstration of the best reduced emission concepts.

Fuel Problems With Marine Gas Turbine Engines

1967 ◽  
Author(s):  
J. P. Attiani
Keyword(s):  
Gas Turbine ◽  
Laboratory Tests ◽  
Operating Experience ◽  
Fuel Oil ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Test Program ◽  
Copper Deposits ◽  
Remedial Actions ◽  
Effect Of Copper

This paper describes a test program undertaken by the Navy to determine the causes of two problems in the fuel-oil systems of gas turbine engines. The first problem concerns short filter life; the second, copper deposits that cause clogging of fuel-oil nozzles. Results are given for operating experience with va-ious filter units from both laboratory tests and fleet experience. The effect of copper deposits on thermal stability is discussed. The author concludes with a review of remedial actions being taken to solve these problems.

Marine Operation of Gas Turbine Engines and Waterjet Pumps for Small Passenger Vessels

1979 ◽  
Author(s):  
S. M. Kowleski ◽  
C. D. Harrington
Keyword(s):  
Gas Turbine ◽  
San Francisco ◽  
High Speed ◽  
San Francisco Bay ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Golden Gate ◽  
Operational Problem ◽  
Golden Gate Bridge ◽  
Selection Of

This paper describes the planning, developmental, equipment selection and operational problem phases of the high-speed ferry system presently being operated on San Francisco Bay by the Golden Gate Bridge, Highway and Transportation District. The reasons for the selection of the vessel propulsion package consisting of gas turbine engines and waterjet pumps are discussed in some detail. Most importantly, the paper covers the problems experienced to date with this equipment in continuous marine operation.

scholarly journals Generalized High Speed Simulation of Gas Turbine Engines

1990 ◽  
Author(s):  
Nanahisa Sugiyama
Keyword(s):  
Real Time ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Speed ◽  
Power Plants ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Jet Engines ◽  
Industrial Gas Turbine ◽  
High Degree

This paper describes a real-time or faster-than-real-time simulation of gas turbine engines, using an ultra high speed, multi-processor digital computer, designated the AD100. It is shown that the frame time is reduced significantly without any loss of fidelity of a simulation. The simulation program is aimed at a high degree of flexibility to allow changes in engine configuration. This makes it possible to simulate various types of gas turbine engines, including jet engines, gas turbines for vehicles and power plants, in real-time. Some simulation results for an intercooled-reheat type industrial gas turbine are shown.

MULTIPARAMETRIC DIAGNOSTICS OF GAS TURBINE ENGINES

2021 ◽  
Vol 156 (A2) ◽  
Author(s):  
J Sinay ◽  
A Tompos ◽  
M Puskar ◽  
V Petkova
Keyword(s):  
Gas Turbine ◽  
High Speed ◽  
Technical Condition ◽  
Diagnostic Methods ◽  
Turbine Engines ◽  
Technical Diagnostics ◽  
Suitable Model ◽  
Gas Turbine Engines ◽  
Advantages And Disadvantages ◽  
The Matrix

This article addresses the issue of diagnostics and maintenance of Gas Turbine Engines which are located in high Speed Ferries, Cruisers, Frigates, Corvettes, etc. Assurance of reliable operation can be performed only by using correct diagnostic methods and procedures of monitoring the condition of the devices and by selecting the correct strategy of maintenance. The issue of monitoring the technical condition of Gas Turbine Engines is treated through multiparametric methods of technical diagnostics incorporated into predictive maintenance, which is a part of proactive maintenance. There are methods of vibrodiagnostics, thermography, tribology, borescopy and emissions measurement. Each of these methods has lots of advantages and disadvantages; therefore it is very important to ensure their correct combination for trouble-free operation of those important facilities. Their suitability at work is discussed in the matrix of diagnostic methods application and the PF chart. The output of the work is a proposal of a suitable model of maintenance control which uses multiparametric diagnostic methods for small and big Gas Turbine Engines and optimizes maintenance costs.

The Testing and Approval of Aircraft Engine Mounted Accessories

1982 ◽  
Vol 196 (1) ◽  
pp. 57-64
Author(s):  
D S Pearson
Keyword(s):  
Gas Turbine ◽  
Aircraft Engine ◽  
Single Frequency ◽  
Turbine Engines ◽  
Severity Assessment ◽  
Gas Turbine Engines ◽  
Shaft Speed ◽  
Unified Approach ◽  
Frequency Excitation ◽  
Environmental Simulation

Vibration measurements on gas turbine engines are normally made using accelerometers. The environment to which engine accessories would be subject has been evaluated by comparing ‘g’ peaks in the frequency spectrum, individually, with empirical yardsticks of severity. Endurance approval testing of accessories to withstand the environment so characterized is normally conducted by applying unidirectional single frequency excitation to simulate engine conditions at a particular shaft speed. These procedures have proved inadequate in predicting failure or verifying corrective measures where accessory problems due to wear phenomena are concerned. This paper analyses reasons for this inadequacy in terms of measurement practice, engine severity assessment, environmental simulation and approval procedures. By recognizing the effect of multi-frequency vibration in three planes it further aims to provide a unified approach to accessory design and development by which service accessory reliability might be improved. Although at first sight more expensive, the approach described will in many cases reduce to previous practice. In cases where greater test expenditure is necessary, loopholes will have been plugged by which many expensive service problems previously escaped.

Analysis of High-Speed Cylindrical Roller Bearing With Flexible Rings Mounted in a Squeeze Film Damper

2007 ◽  
Author(s):  
Cyril Defaye ◽  
Daniel Nelias ◽  
Florence Bon
Keyword(s):  
Gas Turbine ◽  
Load Distribution ◽  
High Speed ◽  
Roller Bearing ◽  
Squeeze Film ◽  
Turbine Engines ◽  
Radial Clearance ◽  
Elastic Coupling ◽  
Gas Turbine Engines ◽  
Squeeze Film Damper

For high-precision mechanical systems such as gas-turbine engines, which operate under extreme conditions, it is particularly important to accurately predict the behavior of the mainshaft rolling bearings. This prediction includes, among others, the load distribution, stiffness and power dissipation. Although shaft speeds tend to increase, rings and shaft walls are becoming thinner due to size and weight constraints. Thus, bearing behavior is no longer independent of the housing and ring stiffness. Furthermore, since forty years, the use of squeeze film damper is largely widespread in gas-turbine engines to significantly reduce the vibratory levels. Due to the flexibility of the ring providing the interface between the roller bearing and the fluid film, it appears an elastic coupling which modifies the behavior of the bearing-squeeze film damper system. This paper presents first a squeeze film damper model with a flexible inner ring (i.e. outer ring of the roller bearing). An analytical stop model is introduced to reproduce the interference between the inner ring of the squeeze film damper and its housing. In a second part, an elastic coupling between the presented squeeze film damper model and an existing roller bearing model is proposed. Finally, the results presented show that this coupling has a first order influence on the behavior of the bearing-squeeze film damper system. It is also shown that the coupling between a roller bearing and a squeeze film damper when linked by a flexible ring introduces a dissymmetry of the load distribution with respect to the applied load direction. Moreover, in certain cases, the position of the bearing in its housing can reach eccentricities larger than the radial clearance of the squeeze film damper.

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