Investigation of the Transient Response of a Dual-Rotor System With Intershaft Squeeze Film Damper

A method is presented for calculating the dynamics of a dual-rotor gas turbine engine equipped with a flexible intershaft squeeze-film damper. The method is based on the functional expansion component synthesis method. The transient response of the rotor due to a suddenly applied unbalance in the high-pressure turbine under different steady-speed operations is calculated. The damping effects of the intershaft damper and stability of the rotor system are investigated.

Vibration Characteristics of 50 Hz, 120 MW Gas Turbine

This paper describes the vibration analysis technology of MW-701D Gas Turbine which was developed by Mitsubishi Heavy Industries, Ltd. for 50 Hz utilities. MW-701D is the highest performance gas turbine available with a firing temperature of 1,154°C for base load operation. It is employed by the 1,090 MW combined cycle plant, one of the largest of its kind in the world, and the plant began commercial operation at half of the total capacity of 1,090 MW in December, 1984. The plant was designed to supply base load electric power generation by burning imported liquefied natural gas (LNG) fuel. This paper describes the general description of the combined cycle plant and the vibration characteristics of MW-701D Gas Turbine.

Diagnostic Procedures for Jet Engines

In the paper to be presented diagnostic procedures on the basis of a gas path analysis are applied on a two-shaft jet engine. Starting from the mathematical model of the engine a filter-algorithm is used which delivers from actual measurement data the state of the engine for different working conditions. The procedure is proven for some examples and discussed in regard of its practical significance.

Improvement of a Cycle J Integral for CT-Specimens

The cycle J integral formula for CT-specimens has been improved as follows Δ J = 2 B b a 1 • U + a 2 • Δ δ + 2 B b U e { -1.2025 a w + 0.6233 0.3 ⩽ a w ⩽ 0.53 -0.02 Sin ⁡ π 0.23 a w - 0.53 0.53 < a w < 0.95 This formula is applicable to the fatigue crack propagation range of 0.3 ≤a/w<0.95. In comparision with other formulae of cycle J integral, the application range of the above expression is enlarged and its precision is also increased to a certain extent.

Investigation Into the Cause of Failure of a Turboprop Impeller in Service

A 2-stage centrifugal flow turboprop Dart engine failed recently in service due to the failure of the low pressure impeller. Examination by various techniques including electron microscopy based on scanning, energy dispersive analysis of x-ray and transmission electron fractography indicates that the cause was metallurgical in nature, resulting from a material manufacturing defect followed by fatigue fracture and finally by tensile rupture of the material.

The Effect of Thermal Matching on the Thermodynamic Performance of Gas Turbine and IC Engine Cogeneration Systems

Computer models have been used to analyze the thermodynamic performance of a gas turbine (GT) cogeneration system and an internal combustion engine (IC) cogeneration system. The purpose of this study was to determine the effect of thermal matching of the load (i.e., required thermal energy) and the output steam fraction (fraction of the thermal output, steam and hot water, which is steam) on the thermodynamic performance of typical cogeneration systems at both full and partial output. The thermodynamic parameters considered were; the net heat rate (NHR), the power to heat ratio (PHR), and the fuel savings rate (FSR). With direct use (the steam fractions being different); the NHR of these two systems is similar at full output, the NHR of the IC systems is lower at partial output, and the PHR and the FSR of the GT systems is lower than the IC systems over the full range of operating conditions. With thermal matching (to produce a given steam fraction) the most favorable NHR, PHR, and FSR depends on the method of matching the load to the thermal output.

Recent Developments in Vibration Monitoring and Diagnostics for Aeroderivative Gas Turbines

Industrial aeroderivative gas turbines are becoming increasingly popular for use in both on-shore and off-shore installations. The characteristics of these machines — high efficiency in simple cycle operation, small size, and light weight — make them ideal for industrial applications. As the aeroderivative gas turbine has become more widely used, the need for more reliable monitoring methods has become increasingly apparent. Traditional velocity transducer based seismic monitoring systems have had several shortcomings when applied to aeroderivative gas turbines. One of these problems was nuisance alarms due to increasing transducer noise output. Another was not detecting increasing casing vibration because of transducer deterioration. Overcoming these problems has required advances in transducer technology as well as changes in signal processing techniques. This paper describes the technology and techniques used in new seismic vibration monitoring systems.

Frequency Distribution of Blades in Turboengines and Vibration Characteristics of Mistuned Blades

In this paper, the probability distribution of blade frequencies is given as a Gaussian distribution approximately. The computations for comparing and simulating the effects of blade mistune on blade-disk vibration are made, which show that in general cases, blade mistune will cause the blade vibration amplitude to increase 20–30%. If the frequency difference of the blades on one stage is within ± 2%, the effect of mistune on the blade vibration will not be obvious. It is suggested that the blades can be divided into groups for mounting them and the frequency difference in each group not exceeds a certain range, for example, ± 2%.

Prediction of Blade Flutter in a Tuned Rotor

This paper is about blade flutter in a tuned rotor. With the aid of the combination of three dimensional structural finite element method, two dimensional aerodynamical finite difference method and strip theory, the quasi-steady models in which two degrees of freedom for a single wing were considered have been extended to multiple degrees of freedom for the whole blade in a tuned rotor. The eigenvalues solved from the blade motion equation have been used to judge whether the system is stable or not. The calculating procedure has been formed and using it the first stage rotating blades of a compressor where flutter had occurred, have been predicted. The numerical flutter boundaries have good agreement with the experimental ones.

A Low-Expansion Superalloy for Gas-Turbine Applications

A high-strength, low-expansion alloy can greatly increase the efficiency of gas turbines by permitting decreased clearances between rotating and stationary parts. This paper describes development work on a series of nickel-iron-cobalt alloys having the desired combination of high strength and low thermal expansion. The first attempts to develop alloys of this type resulted in materials that required extensive thermomechanical processing and were susceptible to the phenomenon of stress-accelerated grain-boundary oxygen embrittlement (SAGBO). Further development resulted in INCOLOY alloy 909, the first low-expansion superalloy combining good resistance to SAGBO with high mechanical properties achieved without restrictive thermomechanical processing. Those substantial improvements were brought about by the addition of 0.3% to 0.6% silicon to a low-aluminum, 38% nickel, 13% cobalt, 1.5% titanium, 4.7% niobium (columbium), balance iron composition.