Gas Turbine Machinery Research Articles

Mathematical thermo‐mechanical analysis on flame‐solid interaction: Steady laminar stagnation flow flame stabilized at a plane wall coupled with thermo‐elasticity model

AbstractA laminar stagnation flow flame stabilized at a plane wall is theoretically analyzed, coupled with a thermo‐elasticity model in the wall. Mathematical models for both the flame and the wall will be proposed, and corresponding analytical solutions based on their dimensionless forms will be obtained. The mathematical analysis of this flame‐solid interaction primarily focuses on the effect of the flame on combustion‐induced thermo‐mechanical stresses and the influence of wall material on flame properties such as flame temperature and stability against extinction. A sensitivity analysis is further performed to examine how thermo‐mechanical stress inside the wall is affected by changes in other combustion conditions (e.g., mixture composition, flame stretch rate). This study offers valuable insights into understanding the interaction between flames and solids, a relationship crucial in engineering applications such as the interaction between combustion processes and blades within gas turbine machinery.

Investigating the frictional force distributions and inter-stage imbalance of a two-stage brush seal

Although a two-stage brush seal (TSBS) plays an important role in gas turbine machinery, few studies have investigated the complex flow and tip frictional force distributions of the TSBS. This article contributes to the ongoing investigation of the TSBS by proposing a 3D slice model employing computational fluid dynamics to analyze the flow and tip frictional force characteristics of a contacting TSBS using the torque balance principle and linear superposition methods. Our calculations reveal that as the inter-stage imbalance of the pressure decreases, so do the aerodynamic and tip frictional forces between the upstream and downstream bristle packs. In addition, the effects of the number of bristle axial rows and protection clearance height on the inter-stage imbalance are analyzed. The results indicate that the TSBS exhibited significantly less leakage and lower aerodynamic and tip frictional forces than a single-stage brush seal. However, the inter-stage pressure differential results in an inter-stage imbalance in the aerodynamic and tip frictional forces that can be aggravated under high pressure conditions. This study determined that reasonable adjustments can be made to the number of bristle axial rows and protection clearance heights of the upstream and downstream stages to alleviate this inter-stage imbalance. The findings of this study contribute to the design and implementation of more efficient TSBSs.Although a two-stage brush seal (TSBS) plays an important role in gas turbine machinery, few studies have investigated the complex flow and tip frictional force distributions of the TSBS. This article contributes to the ongoing investigation of the TSBS by proposing a 3D slice model employing computational fluid dynamics to analyze the flow and tip frictional force characteristics of a contacting TSBS using the torque balance principle and linear superposition methods. Our calculations reveal that as the inter-stage imbalance of the pressure decreases, so do the aerodynamic and tip frictional forces between the upstream and downstream bristle packs. In addition, the effects of the number of bristle axial rows and protection clearance height on the inter-stage imbalance are analyzed. The results indicate that the TSBS exhibited significantly less leakage and lower aerodynamic and tip frictional forces than a single-stage brush seal. However, the inter-stage pressure differential results in an inter-stage i...

Comparative Assessment of the Surface Integrity of AD730® and IN718 Superalloys in High-Speed Turning with a CBN Tool

Nickel-based superalloys are typical materials used in components of aeroengines and gas turbine machinery. The strength properties of these alloys at high temperatures are crucial not only to the performance (e.g., power generation efficiency, energy consumption, and greenhouse gas emissions) of aeroengines and industrial gas turbines, but also to machinability during component manufacturing. This study comparatively evaluated the surface integrity of two superalloys, AD730® and Inconel 718 (IN718), during high-speed finishing turning using cubic boron nitride (CBN) tools. IN718 is a conventional superalloy used for the hot section components of aeroengines and industrial gas turbines, while AD730® is a novel superalloy with enhanced high-temperature mechanical properties and good potential as a next-generation superalloy for these components. High-speed turning tests of two superalloys were conducted using a CBN cutting tool and jet stream cooling. The achieved surface integrity of the AD730® and IN718 superalloys was characterized and analyzed to assess the comparability of these alloys.

Surface Characterization of AD730TM Part Produced in High Speed Turning with CBN tool

AD730TM is a novel superalloy developed for the hot section part in aero engine and gas turbine machinery with enhanced performance. The material is characterized by its excellent high temperature properties for being an alloy possible to manufacture by cast and wrought process compared to other superalloys in the same class such as Inconel718. The material with higher temperature capability means potentially increased energy efficiency as well as less emission in the new engine design. However, there is lack of information on machinability of the material, especially achievable surface quality under high speed machining. Machining process is commonly employed in the manufacturing of hot section part, such as turbine disc, to obtain the final surface quality and tolerance. Surface quality produced by the machining processes is one of the crucial factors to determine the functional performance and correspondent fatigue life time of the parts. The paper will present the results of surface characterization of the part produced by high speed turning with CBN tool. A series machining tests were conducted in the study. Surface morphology on machined samples were investigated with a scanning electron microscope to assess the surface damages and other surface defects induced by the machining processes. 3D surface topology was also analyzed with an Infinite-focus-variant microscope to correlate with machining condition. In addition, effect of tool wear and cutting parameters, such as cutting speed, will also be discussed in the paper.

Fault detection and signal reconstruction for increasing operational availability of industrial gas turbines

The paper presents a generalization of multi-dimensional linear regression to facilitate multi-sensor fault detection and signal reconstruction through the use of analytical optimization. The proposed methodology is founded upon the solution of an optimal signal reconstruction problem. The technique is applied to the real time monitoring of exhaust gas temperature sensors and burner-tip temperature sensors, of a 14MW industrial gas turbine. Key benefits of the proposed technique are that it facilitates (i) real-time detection of sensor faults and the number of sensors that are at fault in a multi-sensor system; (ii) reconstruction of measurements that would normally be expected from the sensor at fault—thereby facilitating improved unit availability; (iii) determining the minimum number of non-faulty sensors that are required to be available to continue unit operation without unduly compromising performance. The use of an analytical formulation to determine (i–iii) means that the resulting technique incurs low computational overhead and is readily applied to real-time monitoring and subsequent remedial action. Experimental results demonstrate the efficacy of the developed procedures to facilitate continued unit operation in the event of sensor faults. Whilst the application to industrial gas turbine machinery is used to focus the study, it should be noted that the proposed techniques are much more widely applicable to numerous industrial and commercial systems.

Budgeting in the Science Intensive Enterprise Strategic Management

The focal points of project management in creation of budgeting system of “Zorya”-“ Mashproekt” , a large Ukrainian manufacturer of gas turbine machinery for gas pipeline systems, power industry and shipbuilding, and position of such instrument as budgeting in factory strategic management are the goal of the article

Residual Reactivity of Burned Gases in the Early Expansion Process of Future Gas Turbines

The present study investigates the chemical evolution of the burned gases in a first-stage nozzle operated under high inlet temperature and pressure conditions as they are foreseen for next-generation high-efficiency gas turbine machinery. Coupled aerothermochemical simulations are performed up to the extreme case of stoichiometric combustion without ulterior dilution. The intent is to provide an estimation of possible consequences arising from the residual reactivity of gases downstream from the combustor. These consequences might affect the future design of the expansion path in order to render nonstationary chemistry compatible with aerodynamics, energetics, and environmental aspects.

Alloy Phase Stability Requirements in Single Crystal Superalloys

AbstractAlloy phase stability is a critical parameter in the design and implementation of nickel-base superalloys. To achieve the high temperature properties required of single crystal superalloys for application in gas turbine machinery, these alloys must have a stable gamma plus gamma prime microstructure for long periods of time at elevated temperatures. Significant deviation from this stable two phase microstructure, due to the precipitation of other phases, results in the loss of critical alloy properties which can have a deleterious impact on engine performance.Empirical methods based on the electron vacancy concept, commonly employed to predict and prevent the formation of undesirable topologically close packed (TCP) phases such as sigma or mu in polycrystalline nickelbase superalloys, are also used with single crystal superalloys. These undesirable phases result in the loss of alloy properties primarily as a result of the depletion of refractory strengthening elements from the superalloy matrix. The consequence of the formation of undesirable TCP phases on alloy properties and subsequent single crystal component behavior is reviewed.

Experiences of a Multiple Gas Turbine Machinery in Fast Patrol Craft

The Swedish Spica-class torpedo boats have been in service now for some years. The experiences of the craft are reported good and some details are given in this paper of the results with the propulsion gas turbine, the gearing, the controllable pitch propeller, and the generator set gas turbine. Air intake problems in small craft are discussed as well as other problems connected with the multiple shaft installation.

Application of Gas Bearings to Closed-System Brayton-Cycle Turbomachinery—Recent Accomplishments and Potential Problem Areas

Several development programs to demonstrate application of gas-lubricated bearings to gas turbine machinery are presently under way. This paper presents design and initial test data for a 24,000 rpm, 1300 F (turbine inlet temperature) gas-bearing Brayton-cycle turbocompressor operating in a closed-loop system. The bearing system design for a two-shaft power plant, consisting of a 50,000 rpm, 1490 F turbocompressor and a 12,000 rpm turboalternator, is also described. Test results to date demonstrate that gas lubrication, per se, of gas turbine machinery is definitely feasible. However, considerable data are still needed to prove the practical utility of gas bearings. A brief discussion of the needed investigations is presented.

LUBRICATION SYSTEM OF WORLD'S FIRST GAS TURBINE TANKER

ORIGINALLY a motor ship, the Shell tanker Auris of 12,000 tons d.w. has since been fitted with gas turbine machinery and successfully completed sea trials last year, thus becoming the first tanker to be driven by a gas turbine. Though operating on the same principle as the gas turbines used in many air‐craft, that in the Auris has a different type of construction to make it more robust, to give it a longer life and to make possible the use of a less refined fuel. The Auris also has a new type hydraulic reversing gearbox designed by the Pametrada research organisation of the British shipbuilding industry for use with the gas turbine which provides for astern as well as ahead movement. In this system, a hydraulic coupling is used for ahead rotation of the propeller while a reversing torque converter is used for astern rotation. To eliminate the 6% slip in the ahead coupling, however, a hydraulically operated friction clutch has been fitted and is engaged under cruising conditions.