The impact of gas turbine compressor rotor bow on aircraft operations

2017 ◽  
Vol 121 (1246) ◽  
pp. 1808-1832 ◽  
Author(s):  
E.O. Smith ◽  
A.J. Neely ◽  
H. Palfrey-Sneddon
Keyword(s):  
Gas Turbine ◽  
Thermal Gradient ◽  
Aircraft Engine ◽  
Turbine Engine ◽  
Operational Capability ◽  
Compressor Rotor ◽  
Hot Air ◽  
Gas Turbine Compressor ◽  
The Impact ◽  
Do So

ABSTRACTWhen a gas turbine engine is shut down it will develop a circumferential thermal gradient vertically across the compressor due to hot air rising from the cooling metal components and pooling at the top. As the hot compressor rotor drum and casing cool and contract in the presence of this thermal gradient, they do so non-uniformly and therefore will bend slightly, in a phenomenon known as rotor bow. Starting an engine under bowed conditions can result in damage, representing a risk to both airworthiness and operational capability. This study consolidates some preliminary findings by the authors relating to the drivers for rotor bow, such as engine geometry, aircraft-engine integration and rotor temperature on shutdown. The commercial and military operational considerations associated with rotor bow are also discussed, including limitations which may result from a bowed rotor; the influence of operations including the final flight and descent profiles, taxi procedures and rapid turnaround requirements; as well as some practical solutions which may be implemented to reduce the impact of rotor bow.

Application of Abrasive Coatings to Clearance Control in the Gas Turbine

1980 ◽  
Vol 102 (1) ◽  
pp. 113-119 ◽  
Author(s):  
J. W. Vogan ◽  
A. R. Stetson
Keyword(s):  
Gas Turbine ◽  
Test Rig ◽  
Plasma Flame ◽  
Turbine Engine ◽  
Abrasive Grains ◽  
Compressor Rotor ◽  
Gas Turbine Compressor ◽  
Clearance Control ◽  
Engine Development ◽  
Vane Tip

Efficiency of a gas turbine is reduced by vane tip losses in the compressor section; also, vane tip/rotor rubs can produce catastrophic failure of a gas turbine engine. This paper describes a test rig and experimental data obtained evaluating abrasive coatings for clearance control between the vanes and the rotor in a gas turbine compressor. Plasma/flame sprayed oxides, carbides and bonded abrasives were tested under conditions duplicating those encountered in the compressor section. The effectiveness of the coatings in grinding away the vane tips to provide minimum clearance without damage to the vane or rotor was determined. Coatings with rough, sharp abrasive grains were most effective. The laboratory tests were confirmed in engine development tests and by application to a compressor rotor now in operation.

Experimental Observations of Thermal Bow due to Natural Convection on a Gas Turbine Compressor Rotor Shaft Analogue

2016 ◽  
Author(s):  
E. O. Smith ◽  
A. J. Neely ◽  
A. P. Butcher
Keyword(s):  
Natural Convection ◽  
Cooling Rate ◽  
Gas Turbine ◽  
Parametric Study ◽  
Thermal Gradient ◽  
Thermal Plume ◽  
Rotor Shaft ◽  
Compressor Rotor ◽  
Numerical Predictions ◽  
Gas Turbine Compressor

This study describes the development of an experimental apparatus designed to provide initial validation of numerical simulations of a gas turbine compressor rotor shaft under thermal bow due to natural convection. The experimental analogue represents a simplified model developed by the authors in previous works, designed to represent the basic elements of a compressor rotor shaft, as part of an ongoing parametric study into the influence of compressor design and integration on the onset time, duration, and severity of thermal bow, and the propensity of an engine to suffer from the Newkirk Effect. The semi-enclosed steel shaft, mounted on a support frame, was heated to approximately 600K in a convective oven before being removed and allowed to cool under ambient conditions. Observations of the shaft under natural cooling were made using several experimental techniques, including temperature profiling using thermographic imaging and a thermocouple array, and physical distortion measurement using linear variable displacement transducer (LVDT) probes. The behaviour of the buoyant plume was also observed using background oriented schlieren (BOS). Using these techniques, the natural convection-driven thermal gradient and resultant physical deformation were measured and recorded over a period of 60 minutes. The observed thermal gradients and resultant thermal bow distortions were then compared to a one-way fluid thermal structural interaction (FTSI) 3D conjugate heat transfer (CHT) computational fluid dynamics (CFD) and finite element analysis (FEA) model developed by the authors, in order to validate the numerical model. The behaviour of the thermal plume from the BOS imagery was also used as a qualitative validation method. The temperature measurements and overall cooling rate measured on the experimental model showed good agreement with the numerical predictions (within 1%); however, uncertainties in the initial phase of the experiment led to error in the numerical prediction of the thermal gradient and resultant thermal bow measurements (error of up to 63%). Noting the uncertainties in the experiment, the agreement between numerical and experimental results with respect to the overall cooling rate indicates that the numerical approach being employed as part of the larger parametric study into gas turbine compressor rotor shaft thermal bow is appropriate and valid.

Account of Film Turbulence for Predicting Film Cooling Effectiveness in Gas Turbine Combustors

1979 ◽  
Author(s):  
G. J. Sturgess
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Cooling Effectiveness ◽  
Turbine Engine ◽  
Film Cooling Effectiveness ◽  
Wide Range ◽  
Engine Combustion ◽  
Turbulence Effects ◽  
The Impact ◽  
Combustor Liner

The paper deals with a small but important part of the overall gas turbine engine combustion system and continues earlier published work on turbulence effects in film cooling to cover the case of film turbulence. Film cooling of the gas turbine combustor liner imposes certain geometric limitations on the coolant injection device. The impact of practical film injection geometry on the cooling is one of increased rates of film decay when compared to the performance from idealized injection geometries at similar injection conditions. It is important to combustor durability and life estimation to be able to predict accurately the performance obtainable from a given practical slot. The coolant film is modeled as three distinct regions, and the effects of injection slot geometry on the development of each region are described in terms of film turbulence intensity and initial circumferential non-uniformity of the injected coolant. The concept of the well-designed slot is introduced and film effectiveness is shown to be dependent on it. Only slots which can be described as well-designed are of interest in practical equipment design. A prediction procedure is provided for well-designed slots which describes growth of the film downstream of the first of the three film regions. Comparisons of predictions with measured data are made for several very different well-designed slots over a relatively wide range of injection conditions, and good agreement is shown.

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.

Modeling of Cyclic Life for Compressor Rotor of Gas Turbine Engine Taking Into Account Production Deviations

2020 ◽  
Author(s):  
Alexandr N. Arkhipov ◽  
Yury A. Ravikovich ◽  
Anton A. Matushkin ◽  
Dmitry P. Kholobtsev
Keyword(s):  
Gas Turbine ◽  
Low Cycle Fatigue ◽  
Probabilistic Modeling ◽  
Gas Turbine Engine ◽  
Critical Zone ◽  
Design Stage ◽  
Cyclic Life ◽  
Engine Operation ◽  
Turbine Engine ◽  
Compressor Rotor

Abstract The regional aircraft with a turbofan gas turbine engine, created in Russia, is successfully operated in the world market. Further increase of the life and reduction of the cost of the life cycle are necessary to ensure the competitive advantages of the engine. One of the units limiting the engine life is the compressor rotor. The cyclic life of the rotor depends on many factors: the stress-strain state in critical zones, the life of the material under low-cycle loading, the regime of engine operation, production deviations (within tolerances), etc. In order to verify the influence of geometry deviations, the calculations of the model with nominal dimensions and the model with the most unfavorable geometric dimensions (worst cases) have been carried out. The obtained influence coefficients for geometric and weight tolerances are then used for probabilistic modeling of stresses in the critical zone. Rotor speed and gas loads on the blades for different flight missions and engine wear are determined from the corresponding aerodynamic calculations taking into account the actual flight cycles (takeoff, reduction, reverse) and are also used for stress recalculations. The subsequent calculation of the rotor cyclic life and the resource assessment is carried out taking into account the spread of the material low-cycle fatigue by probabilistic modeling of the rotor geometry and weight loads. A preliminary assessment of the coefficients of tolerances influence on stress in the critical zone can be used to select the optimal (in terms of life) tolerances at the design stage. Taking into account the actual geometric and weight parameters can allow estimating the stress and expected life of each manufactured rotor.

The Potential Impact of Future Fuels on Small Gas Turbine Engines

1982 ◽  
Author(s):  
J. A. Saintsbury ◽  
P. Sampath
Keyword(s):  
Gas Turbine ◽  
Operating Experience ◽  
Gas Turbine Engine ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Turbine Engine ◽  
The Future ◽  
Potential Impact ◽  
The Impact ◽  
Whitney Aircraft

The impact of potential aviation gas turbine fuels available in the near to midterm, is reviewed with particular reference to the small aviation gas turbine engine. The future course of gas turbine combustion R&D, and the probable need for compromise in fuels and engine technology, is also discussed. Operating experience to date on Pratt & Whitney Aircraft of Canada PT6 engines, with fuels not currently considered of aviation quality, is reported.

Probabilistic Fretting Fatigue Assessment of Aircraft Engine Disks

2009 ◽  
Author(s):  
Michael P. Enright ◽  
Kwai S. Chan ◽  
Jonathan P. Moody ◽  
Patrick J. Golden ◽  
Ramesh Chandra ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Gas Turbine ◽  
Crack Growth ◽  
Stress Gradient ◽  
Random Variables ◽  
Aircraft Engine ◽  
Fretting Fatigue ◽  
Turbine Engine ◽  
Engine Components

Fretting fatigue is a random process that continues to be a major source of damage associated with the failure of aircraft gas turbine engine components. Fretting fatigue is dominated by the fatigue crack growth phase and is strongly dependent on the magnitude of the stress values in the contact region. These stress values often have the most influence on small cracks where traditional long-crack fracture mechanics may not apply. A number of random variables can be used to model the uncertainty associated with the fatigue crack growth process. However, these variables can often be reduced to a few primary random variables related to the size and location of the initial crack, variability associated with applied stress and crack growth life models, and uncertainty in the quality and frequency of non-deterministic inspections. In this paper, an approach is presented for estimating the risk reduction associated with non-destructive inspection of aircraft engine components subjected to fretting fatigue. Contact stress values in the blade attachment region are estimated using a fine mesh finite element model coupled with a singular integral equation solver and combined with bulk stress values to obtain the total stress gradient at the edge of contact. This stress gradient is applied to the crack growth life prediction of a mode I fretting fatigue crack. A probabilistic model of the fretting process is formulated and calibrated using failure data from an existing engine fleet. The resulting calibrated model is used to quantify the influence of inspection on the probability of fracture of an actual military engine disk under real life loading conditions. The results can be applied to quantitative risk predictions of gas turbine engine components subjected to fretting fatigue.

Integrating Systems Engineering Into the USAF Academy Capstone Gas Turbine Engine Course

2011 ◽  
Author(s):  
August J. Rolling ◽  
Aaron R. Byerley ◽  
Charles F. Wisniewski
Keyword(s):  
Engineering Design ◽  
Gas Turbine ◽  
Systems Engineering ◽  
Aircraft Engine ◽  
Gas Turbine Engine ◽  
Turbine Engine ◽  
Technical Management ◽  
Engine Design ◽  
Aeronautical Engineering ◽  
The Many

This paper is intended to serve as a template for incorporating technical management majors into a traditional engineering design course. In 2002, the Secretary of the Air Force encouraged the USAF Academy to initiate a new interdisciplinary academic major related to systems engineering. This direction was given in an effort to help meet the Air Force’s growing need for “systems” minded officers to manage the development and acquisition of its ever more complex weapons systems. The curriculum for the new systems engineering management (SEM) major is related to the “engineering of large, complex systems and the integration of the many subsystems that comprise the larger system” and differs in the level of technical content from the traditional engineering major. The program allows emphasis in specific cadet-selected engineering tracks with additional course work in human systems, operations research, and program management. Specifically, this paper documents how individual SEM majors have been integrated into aeronautical engineering design teams within a senior level capstone course to complete the preliminary design of a gas turbine engine. As the Aeronautical engineering (AE) cadets performed the detailed engine design, the SEM cadets were responsible for tracking performance, cost, schedule, and technical risk. Internal and external student assessments indicate that this integration has been successful at exposing both the AE majors and the SEM majors to the benefits of “systems thinking” by giving all the opportunity to employ SE tools in the context of a realistic aircraft engine design project.

Account of Film Turbulence for Predicting Film Cooling Effectiveness in Gas Turbine Combustors

1980 ◽  
Vol 102 (3) ◽  
pp. 524-534 ◽  
Author(s):  
G. J. Sturgess
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Cooling Effectiveness ◽  
Turbine Engine ◽  
Film Cooling Effectiveness ◽  
Wide Range ◽  
Engine Combustion ◽  
Turbulence Effects ◽  
The Impact ◽  
Combustor Liner

The paper deals with a small but important part of the overall gas turbine engine combustion system and continues earlier published work on turbulence effects in film cooling to cover the case of film turbulence. Film cooling of the gas turbine combustor liner imposes certain geometric limitations on the coolant injection device. The impact of practical film injection geometry on the cooling is one of increased rates of film decay when compared to the performance from idealized injection geometries at similar injection conditions. It is important to combustor durability and life estimation to be able to predict accurately the performance obtainable from a given practical slot. The coolant film is modeled as three distinct regions, and the effects of injection slot geometry on the development of each region are described in terms of film turbulence intensity and initial circumferential non-uniformity of the injected coolant. The concept of the well-designed slot is introduced and film effectiveness is shown to be dependent on it. Only slots which can be described as well-designed are of interest in practical equipment design. A prediction procedure is provided for well-designed slots which describes growth of the film downstream of the first of the three film regions. Comparisons of predictions with measured data are made for several very different well-designed slots over a relatively wide range of injection conditions, and good agreement is shown.

Experimental and Numerical Correlation of Impact of Spherical Projectile for Damage Analysis of Aero Engine Component

2016 ◽  
Vol 66 (2) ◽  
pp. 193 ◽  
Author(s):  
Anuradha Nayak Majila ◽  
Rajeev Jain ◽  
Chandru Fernando D. ◽  
S. Ramachandra
Keyword(s):  
Finite Element ◽  
Gas Turbine ◽  
Gas Turbine Engine ◽  
Metallographic Analysis ◽  
Damage Analysis ◽  
Alloy Plate ◽  
Turbine Engine ◽  
Aero Engine ◽  
Engine Components ◽  
The Impact

<p>Studies the impact response of flat Titanium alloy plate against spherical projectile for damage analysis of aero engine components using experimental and finite element techniques. Compressed gas gun has been used to impart speed to spherical projectile at various impact velocities for damage studies. Crater dimensions (diameter and depth) obtained due to impact have been compared with finite element results using commercially available explicit finite element method code LS-DYNA. Strain hardening, high strain rate and thermal softening effect along with damage parameters have been considered using modified Johnson-Cook material model of LS-DYNA. Metallographic analysis has been performed on the indented specimen. This analysis is useful to study failure analysis of gas turbine engine components subjected to domestic object damage of gas turbine engine. </p><p> </p>

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