Engine Compressor Blades Research Articles

Automatic Defect Detection of Jet Engine Turbine and Compressor Blade Surface Coatings Using a Deep Learning-Based Algorithm

The application of additive manufacturing (AM) in the aerospace industry has led to the production of very complex parts like jet engine components, including turbine and compressor blades, that are difficult to manufacture using any other conventional manufacturing process but can be manufactured using the AM process. However, defects like nicks, surface irregularities, and edge imperfections can arise during the production process, potentivally affecting the operational integrity and safety of jet engines. Aiming at the problems of poor accuracy and below-standard efficiency in existing methodologies, this study introduces a deep learning approach using the You Only Look Once version 8 (YOLOv8) algorithm to detect surface, nick, and edge defects on jet engine turbine and compressor blades. The proposed method achieves high accuracy and speed, making it a practical solution for detecting surface defects in AM turbine and compressor blade specimens, particularly in the context of quality control and surface treatment processes in AM. The experimental findings confirmed that, in comparison to earlier automatic defect recognition procedures, the YOLOv8 model effectively detected nicks, edge defects, and surface defects in the turbine and compressor blade dataset, attaining an elevated level of accuracy in defect detection, reaching up to 99.5% in just 280 s.

Volumetric embedded entities for the IsoGeometric Analysis of complex structures

We propose a convenient methodology for the modeling and analysis of aircraft compressor blades. To meet this goal, IsoGeometric Analysis is put to good use, as it allows for an exact representation of the geometry, especially for the analysis. This work aims at developing numerical tools to handle mechanical analysis, and later on shape optimisation, of 3D aircraft engine compressor blades using IGA. More precisely, our final goal is to carry out shape optimisation of one precise patch belonging to a complex multipatch structure, while having other patches to follow automatically the geometric changes. To meet this goal, work on geometric and modeling aspects are needed, which is the objective of this paper. Using the proposed techniques to perform gradient-based shape optimisation constitutes a work in itself and is therefore not presented here, but will be detailed in a follow-up paper.In our case, the complete blade assembly is represented using several volumetric patches: the airfoil, the platform, the tenon and the fillet. In order to ensure the geometric compatibility between the different patches, we propose an embedded solid element formulation. A mortar method is implemented in order to guarantee the coupling between the various parts of the assembly. The results show a great potential for the proposed approach for blades design, while concurrently offering broad perspectives in terms of applications.

Study on erosion wear characteristics of aero-compressor blades considering distortion degree

A Tabakoff model of a certain type of turboshaft engine compressor blade was established, and the effects of no, mild, moderate, and severe distortions on blade erosion pattern were obtained. Based on particle velocimetry and erosive wear experiments, the Tabakoff model parameters (k12, V1, V2, V3, and θ0) were obtained. The effect of four distortion degrees on blade erosion pattern and erosion rate was studied. With an increase in the distortion degree, the erosion area of the rotor blade pressure surface is found to move toward the leading edge and blade tip. The erosion area of the stator blade suction surface moves toward the leading edge and blade root, whereas that of the pressure surface moves toward the blade root.

Experimental study on transition of dynamic airfoil in pitching oscillation

The transition characteristics of dynamic airfoil have significant effects on the aerodynamic performance of wind turbines, helicopter rotor blades, jet engine compressor blades, etc. The time domain and time-frequency domain characteristics of transition on a NACA0012 airfoil during its pitching oscillation were experimentally studied using wall pressure measurement technology with high time accuracy in this paper. The variable slip window technology was used to detect the transition position, and the proper orthogonal decomposition (POD) method and wavelet analysis were combined to perform the time-frequency analysis. In the gradual forward movement of the transition, the low-frequency instability is gradually enhanced by the main flow and the inverse pressure gradient, and significantly submerges the high-frequency fluctuated feature. The higher order moments of the wall pressure during dynamic airfoil transition deviate significantly from the Gaussian characteristics, which is caused by the low-frequency instability and high-frequency burst. The POD method is able to distinguish low-frequency instability from the high-frequency feature. The reduced frequency had significant effects on the transition. With the increase of the reduced frequency, the hysteresis effect of the transition became more and more significant, and the frequency component of transition was more concentrated and the energy was stronger.

Особливості варіювання просторової форми лопаток при аеродинамічному вдосконаленні компресорів авіаційних газотурбінних двигунів

This work is devoted to the development of procedures for the aerodynamic improvement of gas-turbine engine axial-flow compressor blade rows. The aim of the work is to compare the efficiency of two methods for impeller blade shape variation in the aerodynamic improvement of an aircraft gas-turbine engine two-stage fan. The first method consists only in varying the blade profile angle along the blade height, while the second consists in varying the blade profile angle and geometrical parameters. The features of the approach used in the solution of this problem are as follows: formulating quality criteria as the mean integral values of the power characteristics of each impeller of the fan over the operating range of the air flow rate through the impeller and searching for advisable values of the impeller blade parameters by scanning the independent variable range at points that form a uniformly distributed sequence of small length. The basic tool is a numerical method developed at the Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine, which simulates 3D turbulent gas flows in the compressor stage blade channels using the complete averaged Navier¬–Stokes equations. The results of multiparameter calculations of 3D turbulent gas flows show that at the initial stage of the aerodynamic improvement of compressor blade rows varying the blade profile angle alone is more efficient; however, increasing the number of elements of the uniformly distributed sequence of points in the variable range increases the possibility of finding a point at which the blade profile aerodynamic characteristics significantly improve. The results obtained are expected to be used in the aerodynamic improvement of gas-turbine engine compressor blade rows.

Robotic Grinding Process of Turboprop Engine Compressor Blades with Active Selection of Contact Force

Robotic Grinding Process of Turboprop Engine Compressor Blades with Active Selection of Contact Force

Effect of Laser Surface Texturing on Coating Adherence and Tribological Properties of CuNiIn and MoS2 Coating

Copper nickel indium (CuNiIn) and Molybdenum disulphide (MoS2) duplex coating is used in aero engine compressor blades of Ti6Al4V to prevent fretting failure. Surface before coating is roughened by grit blasting process for coating adhesion. In present study, in place of grit blasting, laser surface texturing (LST) process is used for surface preparation and compared with grit blasted surface. Four different elliptical and square patterns are created by LST on Ti6Al4V. Difference of surface topography between LST and grit blasted surface is analyzed by SEM and white light interferometery. CuNiIn is deposited on Ti6Al4V by atmospheric plasma spray. MoS2 lubricating coating is deposited on top of CuNiIn by spray painting and curing. Effect of difference in surface preparation on coating microstructure as well as on tribological properties is studied. The results showed that geometry and dimensions of LST pattern influence the coating adherence and wear performance. LST process can be optimized for better performance and explored as an alternative surface preparation process in industry for thermal spray 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.

Fabrication and Testing of Rocket Engine Construction Elements by Addictive Production Approach

For the first time, using the technology of selective laser sintering, prototypes of rocket engine compressor blades were manufactured with subsequent analysis of the strength, technological, physical and mechanical characteristics of the product. The physical and mechanical properties of the manufactured blades were investigated, it was found that the short-term strength limit at 20 °C is 1450 MPa, and at 300 °C the ultimate strength is 1300 MPa, thus thermal losses in deformation resistance are no more than 12%, which allows the material to be used in aircraft construction, including for supersonic aircraft

Dimensionality-reduction-based surrogate models for real-time design space exploration of a jet engine compressor blade

Design space exploration (DSE) is a systematic analysis of designs based on parameters that are varied. DSE, however, often involves computationally expensive analyses that require large amounts of time and computer resources. To overcome this obstacle, tools and methods have been developed that allow the designer to quickly explore the design space. One such tool is surrogate modeling. A surrogate model's predictions are based off the relationship between the inputs and the outputs. If this relationship is sufficiently nonlinear, a nonlinear dimensionality reduction technique may unfold the data and create a linear relationship by discovering the data's true dimensionality. The resultant surrogate has the potential to be more accurate due to the simplified relationship between the inputs and outputs. This paper uses surrogate models based on dimensionality reduction to predict finite element analysis (FEA) nodal properties of a jet engine compressor blade. Four different dimensionality reduction methods are compared, namely PCA, KPCA, ISOMAP, and LLE. The results show that nonlinear dimensionality-reduction-based surrogate models can reduce surrogate error in sufficiently nonlinear data spaces. To measure the linearity of the manifold, a new term, called the manifold distance ratio (MDR), is introduced. Nonlinear dimensionality-reduction-based surrogate models can have less error than PCA-based surrogate models when the MDR >1.7. For our application, ISOMAP-based surrogate models decreased the mean error of the surrogate for predicting nodal stresses by 35.7% compared to PCA. The lowest error in predicting the nodal coordinates was the inverse-transform-based PCA. While all errors in nodal coordinates were small, less than 0.23%, the other linear and nonlinear algorithms had between 2.4 and 3.2 times more error.

Failure Analysis of a Fighter Jet Engine Compressor Blade Due to Foreign Object Damage and High-Cycle Fatigue

Failure Analysis of a Fighter Jet Engine Compressor Blade Due to Foreign Object Damage and High-Cycle Fatigue

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.

Using surrogate models to predict nodal results for fatigue risk analysis

Fatigue life analysis and FEA require high computational costs for aerospace models. Goodman diagrams are useful tools for determining the fatigue life of a part, and depend on structural and modal FEA simulations. Surrogate models have been used in fatigue analysis to predict the steady stresses and alternating stresses FEA model for every par node enabling a dynamically-updated Goodman diagram that responds to design parameter changes in real time. This research analyzes a jet engine compressor blade, and compares the accuracy of these nodal surrogate methods to previous surrogate methods where only a single value is predicted for failure analysis. Quantitative data summarizing the error between the single value and full field models are presented for the transonic Purdue blade.

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.

The Objective Space and the Formulation of Design Requirement in Natural Laminar Flow Optimization

Design requirement is as important in aerodynamic design as in other industries because it sets up the objective for the samples in design space to approach. Natural Laminar Flow (NLF) optimization belongs to the type of aerodynamic design problems featured by the combination of distinct aerodynamic performance, where the design requirement is often formulated in form of summation of laminar-related performance and pressure drag performance with different weight assignment according to different perspectives. However, the formulations are rather experience-oriented and are decided non-quantitatively. Inspired by data manipulation approaches in design space (spanned by design variables of geometrical representation parameters) in many aerodynamic designs, this paper proposes new formulations of design requirement in NLF optimization via consideration of objective space (projection of design space through aerodynamics) and shows the impact of the corresponding formulation of design requirement to the result of NLF optimization in cases of transonic airfoil and aero engine compressor blade design from two perspectives: Pareto front convergence and improving effect of accessory performance. The paper uses Principal Component Analysis (PCA) to obtain the eigenvectors of objective space to extract the intrinsic information about specific problem. The method is realized in two cases with satisfactory result.

Thermal Contact Resistance between Aero Engine Compressor Blade and Flexible Fixture

In the process of two-pass micro plasma arc welding of titanium alloy sheet, based on the thermal contact resistance theory, a three-dimensional transient heat transfer finite element model of contact heat transfer between titanium alloy sheet and flexible fixture was established. The effects of contact upper surface temperature, micro-contact thermal resistance, micro-gap thermal resistance, DC and pulse welding on thermal contact resistance were investigated, and the simulation and experimental results were compared. The results show that the thermal contact resistance increases as the temperature increases when the temperature of the contact upper surface (titanium alloy sheet) is in the range of 290–350 K. The effect of micro-contact thermal resistance on the thermal contact resistance is 26.1%–46.3% larger than the micro-gap thermal resistance. The thermal contact resistance of pulse welding is 3.1%–3.5% larger than DC welding. The error of simulation and experimental results of weld pool depth is 8.6%, which verifies the reliability of the model.

Laser Surface Texturing to Enhance CuNiIn Anti-Fretting Coating Adhesion on Ti6Al4V Alloy for Aerospace Application

Copper nickel indium (CuNiIn) anti-fretting coating is applied by thermal spray on compressor blades made up of Ti6Al4V alloy to prevent the failure due to fretting wear in aero gas turbine engine. Grit blasting is carried out on blade root for better mechanical interlocking and adhesive strength of CuNiIn coating. Grit blasting with drawback of grit-particle inclusion and distortion of parts with residual stresses is widely used in industry for surface roughening to increase the area of contact and promote mechanical interlocking of the coatings. The aim of this study is to evaluate the possibility of application of CuNiIn coating on laser textured surface of Ti6Al4V alloy for application on aero engine compressor blades. Laser texturing facility with nanosecond pulsed laser is used to create the two different patterns. Difference in surface properties of grit blasted and laser textured surface before coating was compared. CuNiIn air plasma spray coating is carried out on laser textured and grit blasted samples. AccuraSpray particle diagnostic system is used to record the temperature and velocity of depositing powder. Microstructural characterization of the coatings was carried out and the interface quality was compared. Bond strength of the coating and its relationship with laser textured surface was compared. This study has brought out that adhesive strength and interface quality can be improved for application of CuNiIn coating with laser surface texturing on Ti6Al4V compressor blades for aero engine application.

Thick yet tough TiN coatings deposited by filter cathode vacuum arc technology

There are some high requirements for mechanical property to protective coatings of turbojet engine compressor blades as the appearance of extreme service conditions. The hard coating with high toughness, good adhesion, good wear resistance and excellent load carrying capacity is a potential coating for extreme service conditions in the future. Thick yet tough TiN hard coatings were successfully deposited on 304L stainless steel substrates by magnetic filtered cathodic vacuum arc technology. The morphology, structure and properties of the coatings were studied by SEM and XRD, etc.The results show that the continuous growth of TiN coatings attributed to periodic high energy ion bombardment which can suppress the large grain size and reduce the internal stress. The thickness of TiN coating can reach to 50 μm and the deposition rate was close to 0.2 μm/min. At the same time, the stable non stoichiometric TiN<sub>0.9</sub> can be formed by controlling the constant N<sub>2</sub> flow rate, which can improve the toughness of TiN coatings. All TiN ciatings belong to superhard coating and the max value of hardness and modulus of elasticity were 38.24 GPa and 386.53 GPa respectively. TiN coatings have good adhesion and excellent toughness.The highest <i> <inline-formula><tex-math id="Z-20200510122827-1">\begin{document}$ H/E^{*} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="10-20200036_Z-20200510122827-1.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="10-20200036_Z-20200510122827-1.png"/></alternatives></inline-formula></i> and <inline-formula><tex-math id="Z-20200510122827-2">\begin{document}$ H^3/E^{*2} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="10-20200036_Z-20200510122827-2.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="10-20200036_Z-20200510122827-2.png"/></alternatives></inline-formula><sup> </sup>rate of TiN coating can reach to 0.0989 and 0.3742. Thick yet tough TiN hard coatings have excellent wear resistance with the lowest friction coefficient of 0.26.

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.