High temperature materials in gas turbine engines

The current performance trends in civil, aero and industrial gas turbines are discussed. Future improvements in materials technology are needed for major components — aerofoils, discs and combustors — to achieve improved performances.     

Requirements for engineering ceramics in gas turbine engines

Abstract

The potential uses of ceramics in gas turbine engines are reviewed in the context of the problems arising from the brittle nature of the materials. Material properties are considered in relation to various turbine components and the themes of reliability and component design. It is concluded that substantial efforts will be required in materials and processes in achieving greater reliability and improved design before ceramics are successfully applied in gas turbines.

MST/436     

Advanced gas turbine engines and corrosion problems

It is stressed that it is important to solve the problem of corrosion in engineering. Engineering methods of solving these problems are discussed on examples of increasing the strength reliability of structural elements of long-life gas turbine engines operating under corrosive effect conditions.Translated from Problemy Prochnosti, No. 8, pp. 78–86, August, 1993.     

舰用中冷回热燃气轮机装置动态性能分析

中冷回热循环（ICR）燃气轮机因其优越的全工况性能正日益受到船舶和工业领域的关注。通过分析ICR燃气轮机的变工况特性，采用模块化建模法仿真，对ICR燃气轮机进行动态性能分析，并与简单循环燃气轮机仿真结果进行比较。结果表明，换热器的热惯性对机组的动态性能影响较大，时间常数愈大，达到新平衡所需时问愈长；ICR燃气轮机不仅在设计工况点的效率和功率都有明显提高，而且在低工况下仍有良好的经济性，动力涡轮采用进口导叶面积可调可进一步改善ICR燃气轮机装置的部分工况性能。     

Finite-element models for calculating the temperature fields of underground pipelines

A simple method of constructing finite elements for the numerical modeling of temperature fields, of underground pipelines is outlined.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 49, No. 2, pp. 321–323, August, 1985.     

Tests of NASA ceramic thermal barrier coating for gas turbine engines

A two-layer thermal barrier coating system with a bond coating of nickel-chromium-aluminum-yttrium (Ni-16Cr-6Al-0.6Y, in wt.%) and a ceramic coating of yttria-stabilized zirconia (ZrO₂12Y₂O₃, in wt.%) was tested for corrosion protection, thermal protection and durability. Full-scale gas turbine engine tests demonstrated that this coating eliminated burning, melting and warping of uncoated parts. During cyclic corrosion resistance tests made in marine diesel fuel products of combustion in a burner rig, the ceramic cracked on some specimens. However, metallographic examination showed no base metal deterioration.     

Fatigue strength and life of compressor blades for marine gas turbine engines

An experimental procedure has been developed for the investigation of fatigue and crack growth resistance of materials and real compressor blades. Methods for the determination of stress intensity factors in specimens and in blades with cracks have been justified. Investigations have been performed on the influence of manufacturing residual stresses and surface defects in the form of simulators of dents, corrosion pits, and nonmetallic inclusions on the fatigue strength of steels and a titanium alloy. The characteristics of the material crack growth resistance have been studied taking into account the effect of the medium (sea water), stress ratio in a cycle, and programmed mode of loading. The authors also consider fatigue strength of newly-manufactured blades and those in operation, as well as specific features of fatigue crack propagation in blades. They have substantiated a method for predicting the life of blades with cracks. Institute for Problems of Strength, National Academy of Sciences of Ukraine, Kiev, Ukraine. Translated from Problemy Prochnosti, No. 1, pp. 28–40, January–February, 1999.     

Rossini型气体热量计非稳态温度场的优化分析

为优化Rossini型气体热量计温度场均匀性以减小测量不确定度,采用多重参考系法(MRF)和标准k-ε湍流模型对Rossini型气体热量计的温度场进行三维瞬态数值模拟,分别得到搅拌器转速、燃烧室高度对量热容器内非稳态温度场的影响,特别是对燃烧室与吸热介质之间热传递的影响以及对吸热介质温度均匀性的影响,同时确定温度传感器的最佳安装位置。结果表明:搅拌器桨叶最佳转速为420 r/min,这时燃烧室壁面与吸热介质之间的传热效率最大,并且吸热介质内监测点温度的标准偏差保持在1.5 mK以内。燃烧室高度减小可以提高吸热介质的温度均匀性,加热阶段中,燃烧室高度从180 mm降低到140 mm时,监测点温度的标准偏差从26 mK降低到7.5 mK。温度传感器的最佳安装位置在燃烧室对称轴及导流筒对称轴的等距线上离壳体底部25 mm处。     

Effect of temperature and slope of a gas main in nonisothermal unsteady gas movement

The effect of the temperature and slope of a pipeline on the variation in gasdynamic parameters is studied using numerical methods.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 30, No. 4, pp. 619–624, April, 1976.     

Thermal barrier coatings for thermal insulation and corrosion resistance in industrial gas turbine engines

Four thermal barrier coatings were subjected to a 500 h gas turbine engine test. The coatings were two Y₂O₃-stabilized ZrO₂ composites, Ca₂SiO₄ and CaTiO₃. The Ca₂SiO₄ coating exhibited significant spalling. Y₂O₃-stabilized ZrO₂ and CaTiO₃ coatings showed little degradation except in blade leading edge areas. Post- test examination showed variations in the coating due to manual application techniques. Improved process control is required if engineering quality coatings are to be developed. The results indicate that some leading edge loss of the coating can be expected near the tip.     

Comparison between thin film and bonded powder phosphors forthermographic sensing in gas turbine engines

Measurements of YVO₄:Eu in the form of a thin film and bonded powder, before and after testing in a Rolls-Royce gas turbine engine, indicate that the durability of the thin film was markedly better than that of the bonded powder; there was a 500% increase in loss for the bonded powder. Both thin films and bonded powders showed excellent reproducibility for photoluminescent (PL) decay-time temperature measurement. However, for the thin film, the useful temperature range (660-800 K) and sensitivity (18.4 mK^-1) were much better than the bonded powder (700-800 K and 14.6 mK^-1 ). Evidence here clearly implies that thin films have much better properties for long lifetime thermographic sensing at high temperatures     

Special features of the spectrum of natural vibrations of seals of gas turbine engines

The paper reports the results of a numerical investigation to determine special features of the spectrum of natural vibrations of gas turbine seals in view of their design and technological factors. The authors propose recommendations of how to raise the seal reliability and efficiency.