Characterizing Compressor Rotor Unclamp in a Gas Turbine Engine

2012 ◽  
Author(s):  
Cory Alban ◽  
Masha Tolstykh ◽  
Devin Hilty ◽  
Andrew Bollman
Keyword(s):  
Gas Turbine ◽  
Robust Design ◽  
Extended Period ◽  
Gas Turbine Engine ◽  
Tip Clearance ◽  
Transient Condition ◽  
Element Analysis ◽  
Turbine Engine ◽  
Compressor Rotor ◽  
Secondary Air

In the aerospace industry, many gas turbine compressors rely on a tie bolt to mechanically hold together all rotating components in the compressor rotor. Maintaining this clamp load is essential to the performance of the engine. In the event of an unclamp, the engine will experience a reduction in tip clearance due to a change in rotational dynamics; increased temperatures and pressures in secondary air systems; and a decrease in critical component life. Accordingly, designers must be aware of the variables effecting compressor rotor clamp loads observed for component assembly and operational missions. During testing, an axial gas turbine engine unexpectedly experienced a compressor rotor unclamp which led to an increase in turbine temperature and front sump buffer air temperature and pressure. Further investigation revealed a thermal expansion mismatch between the tie bolt and inner gas path rim during a specific transient condition. Because of this thermal effect, the rotor will experience an unclamped condition which will result in ingesting compressor discharge air into the drum. The compressor rotor will remain unclamped until the engine is operated at a lower power setting or shut down for an extended period. This paper documents and explains the transient condition at which the engine experienced unclamp through review of test data, characterizes the design space around the tie bolt by using heat transfer and structural finite element analysis codes, and shows how robust design tools were used to find an optimized solution that eliminated the risk of thermally driven unclamp through robust design and assembly choices.

The Effect of Heat Transfer Coefficient Increase on Tip Clearance Control in H.P. Compressors in Gas Turbine Engine

2013 ◽  
Author(s):  
Godwin Ita Ekong ◽  
Christopher A. Long ◽  
Peter R. N. Childs
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Gas Turbine ◽  
Time Constant ◽  
Gas Turbine Engine ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Test Facility ◽  
Turbine Engine

Compressor tip clearance for a gas turbine engine application is the radial gap between the stationary compressor casing and the rotating blades. The gap varies significantly during different operating conditions of the engine due to centrifugal forces on the rotor and differential thermal expansions in the discs and casing. The tip clearance in the axial flow compressor of modern commercial civil aero-engines is of significance in terms of both mechanical integrity and performance. In general, the clearance is of critical importance to civil airline operators and their customers alike because as the clearance between the compressor blade tips and the casing increases, the aerodynamic efficiency will decrease and therefore the specific fuel consumption and operating costs will increase. This paper reports on the development of a range of concepts and their evaluation for the reduction and control of tip clearance in H.P. compressors using an enhanced heat transfer coefficient approach. This would lead to improvement in cruise tip clearances. A test facility has been developed for the study at the University of Sussex, incorporating a rotor and an inner shaft scaled down from a Rolls-Royce Trent aero-engine to a ratio of 0.7:1 with a rotational speed of up to 10000 rpm. The idle and maximum take-off conditions in the square cycle correspond to in-cavity rotational Reynolds numbers of 3.1×106 ≤ Reφ ≤ 1.0×107. The project involved modelling of the experimental facilities, to demonstrate proof of concept. The analysis shows that increasing the thermal response of the high pressure compressor (HPC) drum of a gas turbine engine assembly will reduce the drum time constant, thereby reducing the re-slam characteristics of the drum causing a reduction in the cold build clearance (CBC), and hence the reduction in cruise clearance. A further reduction can be achieved by introducing radial inflow into the drum cavity to further increase the disc heat transfer coefficient in the cavity; hence a further reduction in disc drum time constant.

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.

scholarly journals Assessment of Mechanical Design Parameters for an Aero Gas Turbine Engine Jet Pipe Casing using Finite Element Analysis

2020 ◽  
Vol 9 (5) ◽  
pp. 1197-1201
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Gas Turbine ◽  
Mechanical Design ◽  
Three Dimensional ◽  
Gas Turbine Engine ◽  
Design Parameters ◽  
Element Analysis ◽  
Engine Operation ◽  
Turbine Engine

Aero Gas Turbine engines power aircrafts for civil transport application as well as for military fighter jets. Jet pipe casing assembly is one of the critical components of such an Aero Gas Turbine engine. The objective of the casing is to carry out the required aerodynamic performance with a simultaneous structural performance. The Jet pipe casing assembly located in the rear end of the engine would, in case of fighter jet, consist of an After Burner also called as reheater which is used for thrust augmentation to meet the critical additional thrust requirement as demanded by the combat environment in the war field. The combustion volume for the After burner operation together with the aerodynamic conditions in terms of pressure, temperature and optimum air velocity is provided by the Jet pipe casing. While meeting the aerodynamic requirements, the casing is also expected to meet the structural requirements. The casing carries a Convergent-Divergent Nozzle in the downstream side (at the rear end) and in the upstream side the casing is attached with a rear mount ring which is an interface between engine and the airframe. The mechanical design parameters involving Strength reserve factors, Fatigue Life, Natural Frequencies along with buckling strength margins are assessed while the Jet pipe casing delivers the aerodynamic outputs during the engine operation. A three dimensional non linear Finite Element analysis of the Jet pipe casing assembly is carried out, considering the up & down stream aerodynamics together with the mechanical boundary conditions in order to assess the Mechanical design parameters.

Engine Ground Start Characteristics of Fighter Aircraft at High Altitude Airbase

2019 ◽  
Author(s):  
Santhosh Kasram ◽  
Sajath Kumar Manoharan ◽  
Mahesh P. Padwale ◽  
G. P. Ravishankar
Keyword(s):  
High Altitude ◽  
Gas Turbine ◽  
Weather Conditions ◽  
Gas Turbine Engine ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Alternative Methods ◽  
Cold Weather ◽  
Oil Viscosity ◽  
Turbine Engine

Abstract The challenges faced during starting of an aircraft gas turbine engine using a Jet Fuel Starter (JFS) at high altitude airbase are discussed in this paper. Autonomous ground starts at high altitude airbase in soaked sub-zero temperature condition without any external ground support assistance is a challenge. Generally, the start cycle (sub-idle speed) at sub-zero temperatures of a gas turbine engine at high altitudes is influenced by several factors. Drag loads are estimated due to change in lube oil viscosity of engine gearbox and accessory gear box that affects available torque margin of a starter. These estimated loads are superimposed on starter characteristics to identify the available margins for successful starts. The cold start is particularly severe, since it increases the tip clearance between rotor and casing of the engine due to difference in its thermal growth. Higher tip clearances significantly degrade compressor surge margin and results in rotating stall. Inconsistent engine starts were resolved by adopting alternative methods without any change in hardware. This paper presents set of methods used to overcome inconsistent engine starts at high altitude cold weather conditions.

Design and Analysis of a New Accessory Gearbox Housing for a Gas Turbine Engine

2011 ◽  
Author(s):  
Partha S. Das
Keyword(s):  
Gas Turbine ◽  
Low Cycle Fatigue ◽  
Minimum Weight ◽  
Cost Savings ◽  
Gas Turbine Engine ◽  
Cycle Fatigue ◽  
Element Analysis ◽  
Turbine Engine ◽  
Housing Design ◽  
Engine Mount

Accessory Gearbox (AGB) Housing is one of the most critical components of a gas turbine engine that lies between the core engine & the aircraft. The function of the AGB Housing is to provide support for the gear drive assembly that transfers power from the engine to the engine accessories and to the power takeoff drive for the aircraft accessories. The housing also functions as an oil tight container and passageway for lubrication. In addition, the AGB housing provides mount points to attach engine/aircraft support accessories, including the engine mount points to the aircraft. The complexity in predicting AGB housing behavior under the gear loading, engine loading and engine induced vibration is one of the main challenges of designing a new gearbox with minimum weight. To address these issues, the current paper presents for the first time the design-analysis of a new lightweight AGB housing for a turboshaft engine, based on the following three major requirements: i) gear bearing pads strength & stiffness capability, ii) AGB mount pads (for accessories and for engine) load carrying capability, and, iii) vibratory response (mainly high cycle fatigue (HCF) response) of the AGB housing. A 3-D Finite Element Analysis (FEA) model of the AGB housing was developed using the proposed initial design. Various design modifications, involving several interrelated, iterative steps, were then carried out by adjusting and modifying the housing wall thickness, placement & sizes of internal ribs and external gussets, including additional geometric modifications to satisfy the design objectives. The result is a robust, lightweight AGB housing design, eliminating the need for some of the required testing for the qualification of the new gearbox, indicating a significant cost savings. This paper also discusses in detail the methodology for the gear bearing pad strength/stiffness calculation, the FEA modeling techniques for the application of mount loads and gear bearing loads under operating & flight maneuver conditions, and, a methodology for addressing a combined HCF & LCF (Low Cycle Fatigue) response of the housing.

Particulate Monitor for Gas Turbine Cooling Air

2008 ◽  
Author(s):  
Richard H. Bunce ◽  
Francisco Dovali-Solis ◽  
Robert W. Baxter
Keyword(s):  
Gas Turbine ◽  
Monitoring System ◽  
Cooling System ◽  
Gas Turbine Engine ◽  
Minimum Size ◽  
Turbine Engine ◽  
Air System ◽  
Air Cooler ◽  
Secondary Air ◽  
Cooling Air

It is important to monitor the quality of the air used in the cooling system of a gas turbine engine. There can be many reasons that particulates smaller than the minimum size removed by typical engine air filters can enter the secondary air system piping in a gas turbine engine system. Siemens has developed a system that provide real time monitoring of particulate concentrations by adapting a commercial electrodynamic devise for use within the confines of the gas turbine secondary air system with provision for a grab sample option to collect samples for laboratory analysis. This on-line monitoring system is functional at typical engine cooling system piping operating pressure and temperature. The system is calibrated for detection of iron oxide particles in the 1 to 100 micrometer range at concentration of from 1 to 50 parts per million mass wet (ppmmw) The electro dynamic device is nominally operable at 800°C. The particulate monitoring system requires special mounting and antenna. This system may be adjusted for other materials, sizes and concentrations. The system and its developmental application are described. The system has been tested and test results are reviewed. The test application was the cooling air piping of a Siemens gas turbine engine. Multiple locations were monitored. The cooling system in this engine incorporates an air cooler and the particulate monitoring system was tested upstream and downstream of the air cooler for temperature contrast. The monitor itself is limited to the piping system and not the engine gas-path.

Implanted Component Faults and Their Effects on Gas Turbine Engine Performance

1992 ◽  
Vol 114 (2) ◽  
pp. 174-179 ◽  
Author(s):  
J. D. MacLeod ◽  
V. Taylor ◽  
J. C. G. Laflamme
Keyword(s):  
Gas Turbine ◽  
National Research Council ◽  
Engine Performance ◽  
Turbine Rotor ◽  
Gas Turbine Engine ◽  
Tip Clearance ◽  
Turbine Engine ◽  
Turbine Rotor Blade ◽  
Department Of National Defence ◽  
Project Objectives

Under the sponsorship of the Canadian Department of National Defence, the Engine Laboratory of the National Research Council of Canada (NRCC) has established a program for the evaluation of component deterioration on gas turbine engine performance. The effect is aimed at investigating the effects of typical in-service faults on the performance characteristics of each individual engine component. The objective of the program is the development of a generalized fault library, which will be used with fault identification techniques in the field, to reduce unscheduled maintenance. To evaluate the effects of implanted faults on the performance of a single spool engine, such as an Allison T56 turboprop engine, a series of faulted parts were installed. For this paper the following faults were analyzed: (a) first-stage turbine nozzle erosion damage; (b) first-stage turbine rotor blade untwist; (c) compressor seal wear; (d) first and second-stage compressor blade tip clearance increase. This paper describes the project objectives, the experimental installation, and the results of the fault implantation on engine performance. Discussed are performance variations on both engine and component characteristics. As the performance changes were significant, a rigorous measurement uncertainty analysis is included.

scholarly journals A Simplified Gas Turbine Engine Model With Heat Storage/Tip Clearance Effects

1993 ◽  
Author(s):  
T. H. Wong
Keyword(s):  
Gas Turbine ◽  
Heat Storage ◽  
Gas Turbine Engine ◽  
Tip Clearance ◽  
Metal Temperature ◽  
Transient Method ◽  
Transient Responses ◽  
Turbine Engine ◽  
Engine Simulation ◽  
Engine Model

A simplified turboshaft gas turbine engine model called the direct transient method (DTM) model has been developed. The DTM model consists of table look-up data generated from the actual engine data or the transient engine simulation. The DTM model accounts for heat storage, tip clearance and volume dynamics effects. It can, therefore, better predict engine transient responses and turbine metal temperature than the traditional engine horsepower extraction (HPX) model. This paper presents in detail the DTM methodology for generating accurate simplified engine models of transient performance. Comparisons of engine transient responses between the DTM and HPX models are provided.

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