The Phenomena and Criteria Determining the Cracking Susceptibility of Repair Padding Welds of the Inconel 713C Nickel Alloy

The creep-resistant casting nickel alloys (e.g., Inconel 713C) belong to the group of difficult-to-weld materials that are using for precise element production; e.g., aircraft engines. In precision castings composed of these alloys, some surface defects can be observed, especially in the form of surface discontinuities. These defects disqualify the castings for use. In this paper, the results of technological tests of remelting and surfacing by the Tungsten Inert Gas method (TIG) in an argon shield and TecLine 8910 gas mixture are presented for stationary parts of aircraft engines cast from Inconel 713C alloy. Based on the results of metallographic studies, it was found that the main problem during remelting and pad welding of Inconel 713C castings was the appearance of hot microcracks. This type of defect was initiated in the partial melting zone, and propagated to the heat affected zone (HAZ) subsequently. The transvarestraint test was performed to determine the hot-cracking criteria. The results of these tests indicated that under the conditions of variable deformation during the remelting and pad welding process, the high-temperature brittleness range (HTBR) was equal 246 °C, and it was between 1053 °C and 1299 °C. In this range, the Inconel 713C was prone to hot cracking. The maximum deformation for which the material was resistant to hot cracking was equal to 0.3%. The critical strain speed (CSS) of 1.71 1/s, and the critical strain rate for temperature drop (CST), which in this case was 0.0055 1/°C, should be used as a criteria for assessing the tendency for hot cracking of the Inconel 713C alloy in the HTBR. The developed technological guidelines and hot-cracking criteria can be used to repair Inconel 713C precision castings or modify their surfaces using welding processes.

Environmental measures to reduce air pollution on the territory of a specialized facility

A detailed narrowly focused survey was carried out on one of the three zones of the technological infrastructure of a specialized facility - a hangar for aircraft (LA). A general list of pollutants (SV) released into the atmosphere at the 2nd site - the hangar of a special facility was established. Generators – installations and constructs of polluting components on a specific area of stationary and mobile type, which operate at a special facility, are fixed in the selected sectors. In accordance with the nature of the released components and the nature of the emission source (stationary or mobile type), the 2nd site is divided into 4 sectors. The measurement by sectors was implemented and the concentration of emissions was calculated according to the recommended regulatory acts of the Russian Federation. Indications of the concentration of a number of substances above the regulated MPC for 2 sectors of the 2nd site for the energy and test site of the special facility have been established. In connection with the recorded results, techniques and procedures of organizational and technical regulations that contribute to minimizing the accumulation of pollutants (gases) of functioning aircraft engines are analyzed and recommended. A method of attenuation of near-Earth smoke at an interval of up to two meters from the surface where aircraft engines operate is proposed based on the analysis of environmental measures at specialized facilities. The method is based on a variation in the orientation of the outflow of gas flows from functioning aircraft engines during launch, taxiing, takeoff, landing, and passage of an aircraft (VS) along the airfield track.

ECONOMIC AND ECOLOGICAL ASPECTS OF THE USE OF NEW CRYOGENIC AVIATION FUELS

Until recently, the high rates of aircraft engine engineering’s development were ensured by the technological solutions improvement and the desire to approximate as much as possible the ideal thermodynamic cycle of turbojet engines. The traditional fuel for turbojet engines is an aviation kerosene – Jet-A fuel group and their regional analogies. The traditional way of aircraft engines efficiency increasing is a raising of a temperature in front of the high-pressure turbine. New alloys and technologies allow to increase the aircraft engines efficiency to a certain level. Raising the temperature in the combustion chamber by 50 degrees increases the efficiency, which leads to a 5% reduction in fuel consumption. However, this approach is technology limited and does not provide innovative solutions. The aircraft engine engineering’s development tempo in the 21st century continues to accelerate. The main driver of such processes in recent years is the tightening of economic and environmental requirements. Many aircraft manufacturers are actively looking for ways to reach a new qualitative level in terms of turbojet engines economic efficiency and meeting strict environmental requirements. The paper considers the feasibility of using new cryogenic fuels in aircraft turbojet engines, and possible ways for aircraft industry successful development.

Aircraft-engine particulate matter emissions from conventional and sustainable aviation fuel combustion: comparison of measurement techniques for mass, number, and size

Sustainable aviation fuels (SAFs) have different compositions compared to conventional petroleum jet fuels, particularly in terms of fuel sulphur and hydrocarbon content. These differences may change the amount and physicochemical properties of volatile and non-volatile particulate matter (nvPM) emitted by aircraft engines. In this study, we evaluate whether comparable nvPM measurement techniques respond similarly to nvPM produced by three blends of SAFs compared to three conventional fuels. Multiple SAF blends and conventional (Jet A-1) jet fuels were combusted in a V2527-A5 engine, while an additional conventional fuel (JP-8) was combusted in a CFM56-2C1 engine. We evaluated nvPM mass concentration measured by three real-time sampling techniques: photoacoustic spectroscopy, laser-induced incandescence, and the extinction-minus-scattering technique. Various commercial instruments were tested including three LII 300s, one PAX, one MSS+, and two CAPS PMSSA. Mass-based emission indices (EIm) reported by these techniques were similar, falling within 30 % of their geometric mean for EIm above 100 mg/kgfuel (approximately 10 μg PM m−3 at the instrument), this geometric mean was therefore used as a reference value. Additionally, two integrative measurement techniques were evaluated: filter photometry and particle size distribution (PSD) integration. The commercial instruments used were one TAP, one PSAP, and two SMPSs. These techniques are used in specific applications, such as on-board research aircraft to determine PM emissions at cruise. EIm reported by the alternative techniques fell within approximately 50 % of the mean aerosol-phase EIm. In addition, we measured PM-number-based emissions indices using PSDs and condensation particle counters. The commercial instruments used included TSI SMPSs, a Cambustion DMS500, and an AVL APC, and the data also fell within approximately 50 % of their geometric mean. The number-based emission indices were highly sensitive to the accuracy of the sampling-line penetration functions applied as corrections. In contrast, the EIm data were less sensitive to those corrections since a smaller volume fraction fell within the size range where corrections were substantial. A separate, dedicated experiment also showed that the operating laser fluence used in the LII 300 laser-induced incandescence instrument for aircraft engine nvPM measurement is adequate for a range of SAF blends investigated in this study. Overall, we conclude that all tested instruments are suitable for the measurement of nvPM emissions from the combustion of SAF blends in aircraft engines.

Ivchenko-Progress Se State and Prospects of its Development

May 5, 2021 marked the 76th anniversary of the foundation of Zaporizhzhia Machine-Building Design Bureau Progress State Enterprise named after Academician H. Ivchenko (Ivchenko-Progress SE). On May 5, 1945, by order No. 193 signed by the People's Commissar of the Aviation Industry of the USSR O. Shahurin a research and development bureau (RDB) was established at the State Union Plant No. 478 in Zaporozhye to develop new and update earlier designed medium and low power aircraft engines for civil aviation.

Use of Turboprop Fans with the Device for Intensification of Aeration of Open Pits for Ventilation of Mined-Out Space

The application of open-pit fans on the basis of turboprop aircraft engines, working in complex with the devices for intensification of aeration of worked-out space, for ventilation of open-pit mines is considered. The most effective for the open-pit mines ventilation is the use of isothermal jets created by the mine fans with gas-turbine aviation engines. The principle design of the device for intensification of open pits airing represents inclined profiled blades installed on supports. Such a design allows to direct the developed ventilation jet into the quarry, as well as to increase its velocity at the outlet into the mined-out space in the constructions of confusers (blades--top platform of leeward side). The application of the complex, consisting of the ventilation installation and the device of quarries aeration intensification, installed on the surface, allows to increase considerably the volume of the air, supplied to the worked-out space, in comparison with the location of the fan in the pit, to decrease the noise levels in the working zones. By means of modeling qualitative and quantitative aerodynamic characteristics of the offered ventilation scheme (location of the fan and aeration intensifier, pattern of air currents in the quarry, speeds distribution) are defined, its application efficiency and conditions are evaluated

Effect of Overheating Temperature on Thermal Cycling Creep Properties of K465 Superalloy

Turbine blades in aircraft engines may encounter overheating and suffer serious creep property degradation. In this study, the thermal cycling creep experiments were conducted on K465 superalloy under (900 °C/30 min–1100 °C/3 min)/50 MPa, (900 °C/30 min–1150 °C/3 min)/50 MPa and (1000 °C/30 min–1150 °C/3 min)/50 MPa. The investigated thermal cycling creep properties were dramatically degraded, and increasing the overheating temperatures significantly decreased the thermal cycling creep life. The secondary γ′ precipitates obviously dissolved and the area fraction decreased to around 35.2% under (900 °C/30 min–1150 °C/3 min)/50 MPa and (1000 °C/30 min–1150 °C/3 min)/50 MPa, which was almost half that after the standard solution treatment. The decline of the thermal cycling creep properties was mainly due to the significant dissolution of γ′ precipitates. The creep holes/cracks were mainly distributed at the M6C carbides and γ/γ′ eutectics interfaces, M6C carbides and γ′ film interfaces in the grain boundaries, and resulted in the final intergranular fracture.

Remaining Useful Life Estimation of Aircraft Engines Using a Joint Deep Learning Model Based on TCNN and Transformer

The remaining useful life estimation is a key technology in prognostics and health management (PHM) systems for a new generation of aircraft engines. With the increase in massive monitoring data, it brings new opportunities to improve the prediction from the perspective of deep learning. Therefore, we propose a novel joint deep learning architecture that is composed of two main parts: the transformer encoder, which uses scaled dot-product attention to extract dependencies across distances in time series, and the temporal convolution neural network (TCNN), which is constructed to fix the insensitivity of the self-attention mechanism to local features. Both parts are jointly trained within a regression module, which implies that the proposed approach differs from traditional ensemble learning models. It is applied on the Commercial Modular Aero-Propulsion System Simulation (C-MAPSS) dataset from the Prognostics Center of Excellence at NASA Ames, and satisfactory results are obtained, especially under complex working conditions.

A stacked deep convolutional neural network to predict the remaining useful life of a turbofan engine

This paper presents the data-driven techniques and methodologies used to predict the remaining useful life (RUL) of a fleet of aircraft engines that can suffer failures of diverse nature. The solution presented is based on two Deep Convolutional Neural Networks (DCNN) stacked in two levels. The first DCNN is used to extract a low-dimensional feature vector using the normalized raw data as input. The second DCNN ingests a list of vectors taken from the former DCNN and estimates the RUL. Model selection was carried out by means of Bayesian optimization using a repeated random subsampling validation approach. The proposed methodology was ranked in the third place of the 2021 PHM Conference Data Challenge.