Effects of Turbine Tip Clearance on Gas Turbine Performance

2008 ◽  
Author(s):  
Cleverson Bringhenti ◽  
Joa˜o Roberto Barbosa
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Engine Performance ◽  
Outer Wall ◽  
Tip Clearance ◽  
Large Space ◽  
Steady State Condition ◽  
Turbine Engine ◽  
Wall Boundary Layer ◽  
Blade Tip

There are many different sources of loss in gas turbines. The turbine tip clearance loss is the focus of this work. In gas turbine components such as compressor and turbine the presence of rotating blades necessitates a small annular tip clearance between the rotor blade tip and the outer casing. This clearance, although mechanically necessary, may represent a source of large loss in a turbine. The gap height can be a fraction of a millimeter but can have a disproportionately high influence on the stage efficiency. A large space between the blades and the outer casing results in detrimental leakages, while contact between them can damage the blades. Therefore, the evaluation of the sources of the performance degradation independently presents useful information that can aid in the maintenance action. As part of the overall blade loss the turbine tip clearance loss arises because at the blade tip the gas does not follow the intended path and therefore does not contribute to the turbine power output and interacts with the outer wall boundary layer. Increasing turbine tip clearance causes performance deterioration of the gas turbine and therefore increases fuel consumption. The increase in turbine tip clearance may as a result of rubs during engine transients and the interaction between the blades and the outer casing. This work deals with the study of the influence of the turbine tip clearance on a gas turbine engine, using a turbine tip clearance model incorporated to an engine deck. Actual data of an existing engine were used to check the validity of the procedure. This paper refers to a single shaft turbojet engine under development, operating under steady state condition. Different compressor maps were used to study the influence of the curve shapes on the engine performance. Two cases were considered for the performance simulation: constant corrected speed and constant maximum cycle temperature.

Novel resistor-capacitor (RC) network-based capacitance signal conditioning circuit for tip clearance measurement on gas turbine engine

2019 ◽  
Vol 234 (2) ◽  
pp. 342-360
Author(s):  
TN Satish ◽  
A Vivek ◽  
SN Anagha ◽  
ANV Rao ◽  
G Uma ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Direct Current ◽  
Gas Turbines ◽  
Signal To Noise Ratio ◽  
Gas Turbine Engine ◽  
Rotor Blades ◽  
Tip Clearance ◽  
Turbine Engine ◽  
Blade Tip ◽  
Conditioning Circuit

Blade tip clearance is a critical engine health parameter measured on gas turbines. Increase in tip clearance results in decreased efficiency, whereas with decrease in clearance due to thermal and centrifugal loads, rotor blades might rub the engine case. Various sensing techniques are being used, among them, capacitance-based systems are widely used by many engine houses. Among the capacitance conditioning circuits, resistor-capacitor series network-based circuits are simple to implement but pose many challenges during practical development. During the current work, the authors have designed a novel capacitance conditioning circuit combining resistor-capacitor series network, instrumentation amplifiers, and direct current–direct current converters. Performance of the developed capacitance conditioning electronics was evaluated through lab testing and tip clearance measurement on fan stage of an aero gas turbine engine. The prototype conditioner circuit has efficiently conditioned and resolved small capacitances varying from 1.25 pF to 0.00413 pF for running clearances between 0.4 mm and 3 mm, respectively. The developed electronics produced high output with signal-to-noise ratio of 58.1 dB, resolution of 2.5 µm, bandwidth of about 700 kHz, and an accuracy of about 98%. This development has culminated towards miniaturization of the total electronics and has the potential to get developed as smart capacitance sensor. This paper explains the practical aspects and challenges involved while designing and developing such practical conditioning circuits.

Design, Development and Application of Vehicle Gas Turbine Engines

1966 ◽  
Vol 181 (1) ◽  
pp. 149-172
Author(s):  
P. A. Phillips ◽  
Peter Spear
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Low Cost ◽  
Engine Performance ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Design Development ◽  
Turbine Engine ◽  
Wide Range ◽  
Cycle Temperature

After briefly summarizing worldwide automotive gas turbine activity, the paper analyses the power plant requirements of a wide range of vehicle applications in order to formulate the design criteria for acceptable vehicle gas turbines. Ample data are available on the thermodynamic merits of various gas turbine cycles; however, the low cost of its piston engine competitor tends to eliminate all but the simplest cycles from vehicle gas turbine considerations. In order to improve the part load fuel economy, some complexity is inevitable, but this is limited to the addition of a glass ceramic regenerator in the 150 b.h.p. engine which is described in some detail. The alternative further complications necessary to achieve satisfactory vehicle response at various power/weight ratios are examined. Further improvement in engine performance will come by increasing the maximum cycle temperature. This can be achieved at lower cost by the extension of the use of ceramics. The paper is intended to stimulate the design application of the gas turbine engine.

An Application Oriented Gas Turbine Laboratory Experience

2004 ◽  
Author(s):  
Kenneth W. Van Treuren
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Engine Performance ◽  
Data Set ◽  
Actual Performance ◽  
Turbine Engine ◽  
Practical Applications ◽  
Baylor University ◽  
And Performance ◽  
Technology Level

The gas turbine industry is experiencing growth in many sectors. An important part of teaching a gas turbine course is exposing students to the practical applications of the gas turbine. This laboratory proposes an opportunity for students to view an operating gas turbine engine in an aircraft propulsion application and to model the engine performance. A Pratt and Whitney PT6A-20 turboprop was run at a local airfield and engine parameters typical of cockpit instrumentation were taken. The students, in teams of two, then modeled the system using the software PARA and PERF in an attempt to match the manufacturer’s specifications. This laboratory required students to research the parameters necessary to model this engine that were not part of the data set provided by the manufacturer. The research and modeling encompassed areas such as technology level, efficiencies, fuel consumption, and performance. The end result was a two-page report containing the students’ calculations comparing the actual performance of the engine with the manufacturer’s specifications. Supporting graphs and figures were included as appendices. The same type laboratory could be adapted for co-generation gas turbines. Over 121 colleges and universities have co-generation facilities on campus and that presents a unique opportunity for the students to observe the operation of a land-based gas turbine used for power generation. A 5 MW TB5000 manufactured by Ruston (Alstom) Gas Engines is available on the Baylor University campus and is highlighted as an example. Potential problems encountered with using the Baylor University gas turbine are discussed which include lack of appropriate engine instrumentation.

Capacitive Measurement of Compressor and Turbine Blade Tip to Casing Running Clearance

1997 ◽  
Vol 119 (4) ◽  
pp. 877-884 ◽  
Author(s):  
D. Mu¨ller ◽  
A. G. Sheard ◽  
S. Mozumdar ◽  
E. Johann
Keyword(s):  
Gas Turbine ◽  
Measurement System ◽  
Rotor Blades ◽  
Tip Clearance ◽  
Specific Class ◽  
Turbine Engine ◽  
Blade Tip ◽  
Established Fact ◽  
Engine Testing ◽  
Application Requirements

It is an established fact that the efficiency of a gas turbine engine has an inverse relationship with the clearance between the rotor blades and the casing (Tip Clearance, or TC). TC is an essential measurement during the testing of development engines. While commercial TC measurement systems are available, their applicability to an engine is dictated by engine size, geometry, physical accessibility, and temperature distribution around the measurement region. This paper describes the development of a TC measurement system, based on the capacitive measurement principle, which was undertaken to satisfy the application requirements of a specific class of gas turbine engines. The requirements included a relatively long and flexible cable to route the electrical signals out of the engine. The TC measurement system was successfully used during engine testing and valuable data were obtained.

Performance Deterioration in Industrial Gas Turbines

1992 ◽  
Vol 114 (2) ◽  
pp. 161-168 ◽  
Author(s):  
I. S. Diakunchak
Keyword(s):  
Gas Turbine ◽  
Service Time ◽  
Gas Turbines ◽  
Engine Performance ◽  
Turbine Engine ◽  
Factors Affecting ◽  
Preventative Measures ◽  
Industrial Gas Turbines ◽  
Performance Deterioration ◽  
Industrial Gas Turbine

This paper describes the most important factors affecting the industrial gas turbine engine performance deterioration with service time and provides some approximate data on the prediction of the rate of deterioration. Recommendations are made on how to detect and monitor the performance deterioration. Preventative measures, which can be taken to avoid or retard the performance deterioration, are described in some detail.

High Coverage Blade Tip Film Cooling

2004 ◽  
Author(s):  
M. Kuwabara ◽  
Keizo Tsukagoshi ◽  
T. Arts
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Film Cooling ◽  
Gas Turbines ◽  
Separation Bubble ◽  
Density Ratio ◽  
Tip Clearance ◽  
Experimental Program ◽  
Film Cooling Effectiveness ◽  
Blade Tip

More sophisticated cooling schemes are required for the turbine blade due to the demand of increased turbine temperature for improved performance. Although the tip portion of a turbine blade is one of the most critical portions in a gas turbine, there are few studies on cooling this portion compared to those for airfoil, especially film cooling strategies. Industrial gas turbines have a more uniform gas temperature profile than aero engines. For these applications, it is more important to understand the characteristics of tip film cooling to improve the blade durability and gas turbine performance by reducing cooling air. A numerical and experimental program was initiated to study film cooling effectiveness on a flat blade tip as a function of tip gap and mass flux ratios. Flow visualization tests were conducted with and without film cooling to verify the numerical CFD findings. The predictions and visualization results showed that a separation bubble forms at the pressure side edge that increases with tip gap. Film effectiveness measurements were carried out on a 1.3X scale blade model in a low speed test while simulating the normalized pressure distribution typical of an engine design. The engine density ratio of the coolant to mainstream was replicated in the film cooling tests to provide the best simulation of the engine. Two rows of holes were placed near the tip of the blade to provide high film coverage prior to the flowing over the tip. The data shows that film effectiveness increases with decreasing tip clearance. Blowing ratio provides an improvement due to the added mass flow, which was shown by a non-dimensionalized correlation.

Turbine Tip Clearance Measurement System Evaluation on an Industrial Gas Turbine

1997 ◽  
Author(s):  
S. J. Gill ◽  
M. D. Ingallinera ◽  
A. G. Sheard
Keyword(s):  
Gas Turbine ◽  
Measurement System ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Tip Clearance ◽  
Real Time Measurement ◽  
Gap Measurement ◽  
Industrial Gas Turbines ◽  
Blade Tip ◽  
Industrial Gas Turbine

The continuing development of industrial gas turbines is resulting in machines of increasing power and efficiency. The need to continue this trend is focusing attention on minimizing all loss mechanisms within the machine, including those associated with turbine blade tip clearance. In order to study tip clearance in the turbine, real time measurement is required of clearance between turbine blades and the casing in which they run. This measurement is not routinely performed, due to the harsh nature of the turbine environment. On those occasions when turbine tip clearance is measured, it is typically in development vehicles, often using cooled probes that are somewhat unsuitable for use in production gas turbines. In this paper a program of work is reported that was undertaken with the purpose of identifying a promising turbine tip clearance measurement system that used the capacitive gap measurement technique. Issues surrounding the application of three systems to the turbine section of a GE MS6001FA gas turbine are identified and reported. Performance of the three evaluated systems is analyzed.

Performance Deterioration in Industrial Gas Turbines

1991 ◽  
Author(s):  
Ihor S. Diakunchak
Keyword(s):  
Gas Turbine ◽  
Service Time ◽  
Gas Turbines ◽  
Engine Performance ◽  
Turbine Engine ◽  
Factors Affecting ◽  
Preventative Measures ◽  
Industrial Gas Turbines ◽  
Performance Deterioration ◽  
Industrial Gas Turbine

This paper describes the most important factors affecting the industrial gas turbine engine performance deterioration with service time and provides some approximate data on the prediction of the rate of deterioration. Recommendations are made on how to detect and monitor the performance deterioration. Preventative measures, which can be taken to avoid or retard the performance deterioration, are described in some detail.

GSP, a Generic Object-Oriented Gas Turbine Simulation Environment

2000 ◽  
Author(s):  
Wilfried P. J. Visser ◽  
Michael J. Broomhead
Keyword(s):  
Performance Analysis ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Engine Performance ◽  
Object Oriented ◽  
Control Logic ◽  
Turbine Engine ◽  
Industrial Gas Turbines ◽  
On Line ◽  
Turboshaft Engine

NLR’s primary tool for gas turbine engine performance analysis is the ‘Gas turbine Simulation Program’ (GSP), a component based modeling environment. GSP’s flexible object-oriented architecture allows steady-state and transient simulation of any gas turbine configuration using a user-friendly drag&drop interface with on-line help running under Windows95/98/NT. GSP has been used for a variety of applications such as various types of off-design performance analysis, emission calculations, control system design and diagnostics of both aircraft and industrial gas turbines. More advanced applications include analysis of recuperated turboshaft engine performance, lift-fan STOVL propulsion systems, control logic validation and analysis of thermal load calculation for hot section life consumption modeling. In this paper the GSP modeling system and object-oriented architecture are described. Examples of applications for both aircraft and industrial gas turbine performance analysis are presented.

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