Turbine Engine Compressor Blades Research Articles

Vacuum plasma erosion resistant 2D nanocomposite coating Avinit for compressor blades of gas turbine engines of aircraft engines

The work is devoted to the search for new vacuum-plasma coatings with high hardness to increase the durability of the compressor blades of the GTE of aircraft engines Ti-Al-N-based vacuum-plasma coatings obtained by Avinit technologies, which ensure the application of hard, high-quality coatings with dramatically reduced micro-arc damage, were selected as candidates. Avinit multilayer coatings have higher functional characteristics than TiN (microhardness, crack resistance, temperature resistance, erosion and corrosion resistance) and may be promising for applying erosion-resistant coatings for compressor blades. Avinit technologies are technologically closest to the vacuum-plasma technologies used in industrial production for applying TiN protective coatings. New multi-layered 2D nanocomposite wear-resistant ion-plasma hard coatings Avinit (TiN-AlN)n have been developed. The created software products made it possible to reach a qualitatively new level in terms of further modification and improvement of the designs of Avinit functional coatings, stability of technologies and improvement of their quality control when applying such coatings for use in the production of compressor blades of gas turbine engines of aircraft engines. Special attention is paid to methods of preliminary ion-plasma treatment of surfaces before coating. Metallographic studies of the chemical and phase composition and structure of Avinit (TiN-AlN)n coatings have been carried out. The thickness of the coatings is 7-9 μm, the microhardness is 34-35 GPa (compared to the serially used TiN coating: 27.4 GPa). The use of three-stage ion-plasma treatment in Avinit technologies using a double vacuum-arc discharge followed by the application of strengthening coatings in a single technological cycle eliminates the formation of cracks and ensures the production of tightly bonded, high-quality coatings of a given composition with the maximally reduced share of the droplet component. The developed coatings (TiN-AlN)n were applied to experimental batches of working compressor blades of GTE aircraft engines for bench tests.

Experimental and Computational Study of Mechanical and Thermal Characteristics of h-BN and GNP Infused Polymer Composites for Elevated Temperature Applications

Polymer-based nanocomposites are being considered as replacements for conventional materials in medium to high-temperature applications. This article aims to discover the synergistic effects of reinforcements on the developed polymer-based nanocomposite. An epoxy-based polymer composite was manufactured by reinforcing graphene nanoplatelets (GNP) and h-boron nitride (h-BN) nanofillers. The composites were prepared by varying the reinforcements with the step of 0.1 from 0.1 to 0.6%. Ultrasonication was carried out to ensure the homogenous dispersion of reinforcements. Mechanical, thermal, functional, and scanning electron microscopy (SEM) analysis was carried out on the novel manufactured composites. The evaluation revealed that the polymer composite with GNP 0.2 by wt % has shown an increase in load-bearing capacity by 265% and flexural strength by 165% compared with the pristine form, and the polymer composite with GNP and h-BN 0.6 by wt % showed an increase in load-bearing capacity by 219% and flexural strength by 114% when compared with the pristine form. Furthermore, the evaluation showed that the novel prepared nanocomposite reinforced with GNP and h-BN withstands a higher temperature, around 340 °C, which is validated by thermogravimetric analysis (TGA) trials. The numerical simulation model is implemented to gather the synthesised nanocomposite’s best composition and mechanical properties. The minor error between the simulation and experimental data endorses the model’s validity. To demonstrate the industrial applicability of the presented material, a case study is proposed to predict the temperature range for compressor blades of gas turbine engines containing nanocomposite material as the substrate and graphene/h-BN as reinforcement particles.

TECHNOLOGY FOR RESTORATION AND REPAIR OF AIRCRAFT ENGINE PARTS

Problems of increasing the service life of compressor blades of aircraft gas turbine engines using detonation spraying technology are considered. The simulation of the parameters of the velocity and temperature of the particles of the sprayed material in the barrel of the detonation unit and in the flooded space to the substrate was carried out, followed by the choice of the optimal technological parameters of the spraying process. The control system of the detonation unit has been modernized. An experiment was carried out on the deposition of the Al2O3 coatings on the samples of a substrate made of titanium alloy VT3-1. Based on the results of the experiment, technological recommendations were developed concerning both the parameters of the spraying process and the parameters of the preparation of the substrate surface before spraying. The equipment for brazing the blades of the guide vanes is described and a device for spraying coatings on the end surfaces of the compressor blades is proposed. Thus, a complex technology has been developed for restoring the end surfaces of titanium alloy compressor blades by deposition of Al2O3 coatings.

Numerical and Experimental Assessment of the Effect of Residual Stresses on the Fatigue Strength of an Aircraft Blade.

The work presents the results of numerical fatigue analysis of a turbine engine compressor blade, taking into account the values of initial stresses resulting from surface treatment-shot-peening. The values of the residual stresses were estimated experimentally using X-ray diffraction. The paper specifies the values of the residual stresses on both sides of the blade and their reduction due to cutting through the blade-relaxation. The obtained values of the residual stresses were used as initial stresses in the numerical fatigue analysis of the damaged compressor blade, which was subjected to resonant vibrations of known amplitude. Numerical fatigue ε-N life analysis was based on several fatigue material models: Manson’s, Mitchell’s, Baumel-Seeger’s, Muralidharan-Manson’s, Ong’s, Roessle-Fatemi’s, and Median’s, and also on the three models of cyclic hardening: Manson’s, Xianxin’s, and Fatemi’s. Because of this approach, it was possible to determine the relationship between the selection of the fatigue material ε-N model and the cyclic hardening model on the results of the numerical fatigue analysis. Additionally, the calculated results were compared with the results of experimental research, which allowed for a substantive evaluation of the obtained results. These results are of great scientific and practical importance. The problem of determining the fatigue life of blades with defects operating under resonance vibrations is one of the original tasks in the field of fracture mechanics and experimental mechanics. The results obtained are of great importance in the aviation industry and can be used during engine maintenance and inspections to assess the suitability of blades with defects in terms of the needs of further work. This aspect of engineering maintenance is of great importance from the aircraft safety point of view.

High Strain Rate Behavior of GTM-900 Titanium Alloy

Abstract GTM-900 is an α + β alloy of titanium used in low-pressure (LP) compressor blades of gas turbine (GT) engines. The maximum allowable operating temperature of this alloy is 500°C. Silicon is added to enhance the creep resistance at elevated temperatures. The aim of this work is to establish the microstructural stability of this alloy and determine the high strain rate Johnson-Cook (J-C) material parameters such as A, B, and n. The material parameters are subsequently used by designers to simulate the “blade-off” and “casing containment” capability of the LP compressor blade. Split Hopkinson tensile bar was used to conduct high strain rate tests at about 2,000 s−1, and at three different temperatures, viz., 25°C, 300°C, and 500°C, to simulate critical conditions. Data obtained from these testing were used to construct a J-C model. Flow stress increased with an increase in strain rate and decreased with an increase in temperature because of thermal softening. Characterization, using optical and electron microscopes, indicated that the microstructure was stable even after the deformation at 500°C. The presence of needle-like silicide phase was observed under transmission electron microscopy and the composition was verified with X-ray diffraction results. A high strain hardening rate was observed even at elevated temperatures in this alloy (n ≈ 0.54 at 2,000 s−1 and 500°C) compared to Ti-6Al-4V titanium alloy (n ≈ 0.28). Considering good strength and microstructural stability up to 500°C, the present material offers to be an attractive alternate to other contemporary titanium alloys currently used in GT engine applications.

Manufacture and Dimensional Verification of a Gas Turbine Engine Compressor Blade Produced via Additive Manufacturing Method using Ti6Al4V

Bu çalışmada, bir gaz türbin motoruna ait kompresör palesinin, Ti6Al4V alaşımından Eklemeli Üretim (EÜ) yöntemiyle üretimi ve boyutsal doğrulama ölçümleri gerçekleştirilmiştir. Havacılık endüstrisinde yaygın kullanılan Direkt Metal Lazer Sinterleme (DMLS) yöntemi seçilmiştir. İmalattan sonra her bir palede 87 adet olmak üzere toplam 174 yüzey ölçümü gerçekleştirilmiştir. Ölçümlerde, katı modele oranla, 1 Nu’lı palede ortalama +0,0944/-0,0809 mm arasında, 2 Nu’lı palede ortalama +0,1093/-0,0978 mm değişim olduğu belirlenmiştir. Her iki paledeki geometrik değişimin birbiri ile tutarlı sonuçlar verdiği gözlemlenmiştir. Sonuç olarak, bir uçar-parçanın uçağa takılmasına yönelik uçuşa elverişlilik çalışmaları konusuna girmeden, bir gaz türbin motoru kompresör palelerinin Ti6Al4V alaşımından EÜ yöntemi ile üretilebileceği ortaya konulmuştur.

Manufacture and Dimensional Verification of a Gas Turbine Engine Compressor Blade Produced via Additive Manufacturing Method using Ti6Al4V

Bu çalışmada, bir gaz türbin motoruna ait kompresör palesinin, Ti6Al4V alaşımından Eklemeli Üretim (EÜ) yöntemiyle üretimi ve boyutsal doğrulama ölçümleri gerçekleştirilmiştir. Havacılık endüstrisinde yaygın kullanılan Direkt Metal Lazer Sinterleme (DMLS) yöntemi seçilmiştir. İmalattan sonra her bir palede 87 adet olmak üzere toplam 174 yüzey ölçümü gerçekleştirilmiştir. Ölçümlerde, katı modele oranla, 1 Nu’lı palede ortalama +0,0944/-0,0809 mm arasında, 2 Nu’lı palede ortalama +0,1093/-0,0978 mm değişim olduğu belirlenmiştir. Her iki paledeki geometrik değişimin birbiri ile tutarlı sonuçlar verdiği gözlemlenmiştir. Sonuç olarak, bir uçar-parçanın uçağa takılmasına yönelik uçuşa elverişlilik çalışmaları konusuna girmeden, bir gaz türbin motoru kompresör palelerinin Ti6Al4V alaşımından EÜ yöntemi ile üretilebileceği ortaya konulmuştur.

Influence of chrome electroplating on fatigue strength of parts

The article is devoted to the results of studies, which have been conducted on parts with electrolytic chromium in order to determine the effect of the coating on fatigue strength of their. The work was performed in observance of standards, which are fixed in GOST RV 2840-001-2008. Samples for the tests were made from standard gas turbine engine compressor blades. We used a VEDS- 1500 electrodynamic vibration stand with an UMK-12K power amplifier to excite vibrations. It has been shown that the minimum endurance limit of 46 kgf/mm2 based on 2 ∙ 107 cycles, established on uncoated parts, didn't decrease during fatigue tests of compressor blades with an electroplated chrome layer. It should be stressed that the influence of the geometry of the chrome-plated part on the reduction of the endurance limit has been established.

Influence of the stressed state of the surface layer on the endurance of gas turbine engine compressor blades

Different types of final strengthening treatment of gas turbine engine (GTD) compressor blades are considered. The influence of each type of treatment on the formation of roughness of the surface with favorable microrelief, as well as on the level and depth of distribution of residual compressive stresses in the compressor blade airfoil is analyzed. The causes of blade fatigue failure are described and methods of controlling this kind of failure are presented. The results of testing special specimens made of VT9 titanic alloy are presented to establish the influence of final strengthening treatment modes on the compressor blade resistance to fatigue stress. The results of testing residual stress distribution along the thickness of compressor blade airfoil are presented. A method of improving dynamic strengthening of specimens due to the protection of compressor blade edges is discussed. The results of semi-graphical analysis of the stressed state of low-pressure and medium-pressure compressor blades made of VT9 alloy are presented. They take into account residual stresses, as well as operating load stresses in the process of operation. We show that it is possible to increase the limit of the blade endurance due to the optimization of residual stress diagrams by improving the final strengthening technology with the use of dust blasting.

Development of a Touch Probing System for Gaging the Compressor Blades of the GTE

The article describes the touch probing system with the strain gage as the main measuring element. The device has small geometric dimensions and it was developed to measure the gas turbine engine compressor blades. To select the optimum configuration of the probing system, mathematical models of two principal configurations were developed. Simulation modeling of the force of the measured surface impact on the measuring tip was carried out in the Ansys environment for these assemblies. On the basis of practical experiments, the diagram of the deviation of the probe on the resistance of the strain gage was constructed. Reference element were measured to determine the accuracy of the designed touch probing system.

Determination of the critical plane and durability estimation for a multiaxial cyclic loading

An analytical procedure is proposed to determine the critical plane orientation according to the Findley criterion for the multiaxial cyclic loading. The cases of in-phase and anti-phase cyclic loading are considered. Calculations of the stress state are carried out for the system of the gas turbine engine compressor disk and blades for flight loading cycles. The formulas obtained are used for estimations of the fatigue durability of this essential element of structure.

Restoration of Aircraft Gas Turbine Engine Titanium Compressor Blades by Laser Surfacing

A procedure and proposed recommendations are developed for restoring VT8 titanium aircraft gas turbine engine compressor blades using powder surfacing with a fiber laser. A procedure is suggested for restoring defective sections and building up titanium blade vane elements on the example of alloy VT8 using powder materials PTOM-1 and VT25U. It is shown that a pulsed laser operating regime during surfacing and minimization of surfacing layer thickness reduces the time for metal in an overheated condition, which ensures a reduction in the possibility of crack and pore formation, and also formation of a coating ultrafine structure.

Erosion-resistant coatings for gas turbine engine compressor blades

The erosion-resistant ZrN and Cr3C2 coatings intended for the protection of the titanium and steel blades in a GTE compressor are studied. The erosion resistance of the substrate–coating composition is shown to depend on the coating thickness, the deposition conditions, and the coating texture. Ion-assisted deposition changes the structure–phase state of a coating and substantially increases its erosion resistance. It is found that a nanolayer 2D TiN/CrN coating with an average nanolayer thickness of ~60 nm is the best erosion- corrosion-resistant coating for titanium alloys and that a (NiCrTiAlHf)C + CrC coating formed by ionassisted deposition is the best coating for steels. The testing of alloy VT8 compressor blades in an engine supported high protective properties of the nanolayer TiN/CrN coating.

Effect of technological heredity on the fatigue strength in the manufacture of gas turbine engine blades

In the study, the task of researching of the finishing-strengthening machining stage of gas turbine engine compressor blades manufactured of titanium and nickel-chromium alloys in order to extend their service life was solved. The application of electrochemical pulse machining as a technological heredity barrier was substantiated since this method allows a considerable decrease of the residual stress and surface layer work hardening. To ensure the extended service life of blades, the conditions for the subsequent finishing-strengthening machining were identified.

Study of uncertainty of measuring geometrical parameters of gas turbine engine compressor blade profiles

Compressor blades are among the numerous and complicated parts of gas turbine engines. A freeform surface of compressor blades is characterized by a complex of parameters distinguishing the geometry of their individual sections. The paper presents a model of calculating a complex of geometric parameters of blade profiles by a measured array of points. A method of estimating the uncertainty of measurement of a set of geometrical parameters with the use of coordinate measuring machines is developed. Software algorithms have been designed for the implementation of the proposed models and methods. The paper presents the results of analyzing errors of measurement of a set of geometrical parameters of the gas turbine engine compressor blade airfoil. We obtained the probabilistic characteristics of arising errors for three cross sections of the blade airfoil. The proposed models and algorithms for computing a complex of geometric parameters of the measured profiles by an array of points can be applied to software for measuring machines.

Results of Investigative Tests of Gas Turbine Engine Compressor Blades Obtained by Electrochemical Machining

The paper highlights results of the investigative tests of GTE compressor Ti-alloy blades obtained by the method of electrochemical machining with oscillating tool-electrodes, carried out in order to define the optimal parameters of the ECM process providing attainment of specified blade quality parameters given in the design documentation, while providing maximal performance. The new technological methods suggested based on the results of the tests; in particular application of vibrating tool-electrodes and employment of locating elements made of high-strength materials, significantly extend the capabilities of this method.

Technique of Decomposition of Form Deviation for Freeform Surfaces

This paper presents the technique of decomposition of form deviation based on the use of wavelet filter and Fourier transform. The method allows decomposing the total deviation into systematic, random systematic (waviness) and random components. The method testing was carried out for the statistics of the deviation of the suction side of the turbine engine compressor blade. The accuracy check of the estimates of form deviations generated by the method in a series of simulated surfaces with pre-laid characteristics was carried out. The results showed that the method of decomposition allows one to estimate exactly the components of the form deviation of the simulated surfaces in their series.

Designing Forging and Die Tooling for the Manufacture of Turbine Engine Compressor Blades in Siemens NX

For designing forging and die tooling for bulk forging a necessity in using the data of the geometry of the part produced arises. Obviously, the use as a data source for designing drawings of commonly applied in “manual alternate design” (without a computer) especially such complex parts as compressor blades is not perspective because of the complexity of developing theoretical contour specified by a point cloud. In this case the use of special tooling of direct modeling that provides changing the original model of the part developed by the designers is a perspective one. It should be taken into account during the process of forging and die tooling designing that it is necessary to register the special features of the technology, upon that, the technologist should be highly proficient in using the software. The work given describes the designing technique of gas turbine compressor blade with the account of using the potential of NX Siemens program.

Перспективы использования технологии лазерной наплавки для восстановления лопаток компрессоров газотурбинных двигателей

Перспективы использования технологии лазерной наплавки для восстановления лопаток компрессоров газотурбинных двигателей

Comparative research of algorithms of measuring the geometry of complex profiles of gas turbine engine compressor blades

В статье приводятся три алгоритма измерения геометрии пера лопаток компрессора газотурбинного двигателя (ГТД) (спинки, корыта, входной и выходной кромок) на координатно-измерительных машинах. Первый алгоритм представляет собой однократное сканирование измерительным наконечником сечений лопатки по высоте. Второй алгоритм основан на предварительном совмещении номинального профиля с измеряемым действительным профилем. Для выполнения процедуры наилучшего совмещения измеренного профиля с его номинальными значениями использовался итеративный алгоритм ближайших точек. В третьем алгоритме координаты измеряемых точек кромок вычисляются с использованием сплайна, задаваемого по координатам центров измерительного наконечника (ИН). Выполнено исследование погрешностей измерения геометрии элементов с использованием рассматриваемых алгоритмов. Для выполнения исследований была разработана модель касания ИН об измеряемую поверхность детали, позволяющая рассчитывать координаты точки касания, координаты центра  ИН и координаты измеренных точек. Поиск координат точки касания осуществлялся с использованием метода последовательного квадратичного программирования. Применена методика, позволяющая имитировать отклонение формы и расположения действительной поверхности от номинальной.  В ходе моделирования были получены зависимости, позволяющие определить средние, нижние и верхние границы распространения погрешности измерения для любой измеряемой точки пера лопатки.&nbsp