Electrical and Optical Characterization Methodologies for Advanced Spark Ignition

Due to the high transiency and high voltage characteristics of spark ignition, precise measurements are in demand for efficient ignition in future clean combustion engines. The practical challenges of SI systems arise as the gaseous substances vary extensively in density, flow, and temperature. In this paper, a typical transistor coil ignition system with a current management module maintains the transient discharge condition for more credible measurements. Suitable apparatus with FPGA multi-task control systems are established to effectively control and stabilize the discharge current level and duration. The electrical waveforms and spark plasma patterns are correlated, via concurrent electric probing and shadowgraph imaging, under quiescent and flow conditions. The multi-task FPGA provides synchronization of ignition control and data acquisition. The empirical setup and analyzing methods of this work provide essential guidance for facilitating broader innovations in spark ignition, and for advancing the clean and efficient combustion in automotive and aviation engines.

Impact of a Synthetic Component on the Emission of Volatile Organic Compounds during the Combustion Process in a Miniature Turbine Engine

This paper refers to the study of biofuel as an alternative power source for turbine aviation engines. Blends of Jet A-1 fuel and synthesized hydrocarbons from Hydrotreated Esters and Fatty Acids (HEFA) technology at different proportions, such as 25%, 50% and 75%, were used for tests. All the test results were compared with the neat Jet A-1 fuel. A miniature GTM series turbojet engine was used in the test rig studies. During the tests conducted at a specific rotational speed, selected engine operating parameters as well as the emission of volatile organic compounds were measured. In terms of engine performance, no significant differences were found between the test fuels. The results of volatile organic compound emissions indicate that among the most toxic compounds the highest concentrations were obtained for benzene. The addition of the HEFA synthetic component and increasing its proportion in the blend resulted in the obtained concentration values for benzene showing a decreasing trend. The plotted utility profile indicates that the most optimal blend, i.e., the least toxic, is the blend with the share (v/v) of 62.5% of Jet A-1 fuel and 37.5% of HEFA component.

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

Performance of Relative Clearance Ratio of Floating Ring Bearing for Turbocharger-Rotor System Stability

The floating ring bearing (FRB) has been widely used in the field of high-speed rotating machinery such as turbochargers, aviation engines and so on, because of its simple structure, high efficiency and low power consumption. In order to obtain the best ratio between inter-oil clearance and shaft radius of the floating ring bearing necessitates the design reference of dimensional parameters for the design of floating ring bearings. This study, based on the transfer-matrix method, developed the dynamic model of the floating ring bearing-rotor system, and, using the Runge–Kutta analysis method for floating ring bearings, the influence of oil film relative clearance ratio of floating rings on rotor system stability was analyzed and studied. The optimum clearance ratio between inner oil film and the shaft of floating ring bearings is λ = 0.01. This research can provide some theoretical support for the design of parameters and fault diagnosis of rotor floating ring bearing systems.

Methods of clustering parameters in the creation of neural network multi-mode dynamic models of aircraft engines

The presence on modern aviation gas-turbine engines of dozens and even hundreds of sensors for continuous registration of various parameters of their operation makes it possible to collect and process large amounts of information. This stimulates the development of monitoring and diagnostic systems. At the same time the presence of great volumes of information is not always a sufficient condition for making adequate managerial decisions, especially in the case of evaluation of the technical condition of aviation engines. Thus it is necessary to consider, that aviation engines it is objects which concern to individualized, i.e. to such which are in the sort unique. Therefore, the theory of creating systems to assess the technical state of aircraft engines is formed on the background of the development of modern neural network technology and requires the formation of specific methodological apparatus. From these positions in the article the methods which are used at carrying out clustering of the initial information received at work of modern systems of an estimation and forecasting of a technical condition of aviation gas-turbine engines are considered. This task is particularly relevant for creating neural network multimode models of aircraft engines used in technical state estimation systems for identification of possible failures and damages. Metric, optimization and recurrent methods of input data clustering are considered in the article. The main attention is given to comparison of clustering methods in order to choose the most effective of them for the aircraft engine condition evaluation systems and suitable for implementation of systems with meta-learning. The implementation of clustering methods of initial data allows us to breakdown diagnostic images of objects not by one parameter, but by a whole set of features. In addition, cluster analysis, unlike most mathematical-statistical methods do not impose any restrictions on the type of objects under consideration, and allows us to consider a set of raw data of almost arbitrary nature, which is very important when assessing the technical condition of aircraft engines. At the same time cluster analysis allows one to consider a sufficiently large volume of information and sharply reduce, compress large arrays of parametrical information, make them compact and visual.

METHODICAL ASPECTS OF THE LTO CYCLE USE FOR ENVIRONMENTAL IMPACT ASSESSMENT OF AIR OPERATIONS BASED ON THE WARSAW CHOPIN AIRPORT

The aviation engines homologation process takes place in LTO (Landing and Take-Off) test cycle. Mentioned procedure is good for the approval applications because the test conditions are repeatable and obtained results could be compared between different engines. The authors compared in this article the exhaust emission results obtained in LTO test cycle during selected engine homologation with values obtained in estimations. Two Allied Signal TFE731-2-2B engines with a thrust of 15.6 kN were taken into considerations. The engines are used to propel the popular VLJ (Very Light Jet) aircraft: Dassault Falcon 100. Adopted methodology of emission estimation is very similar to the LTO, because the authors use the emission factors obtained in LTO cycle, specified for selected engines. Also, the duration of take-off, climb-out and approach LTO phases were adopted to the estimations. In the analyzed case, 16 scenarios of taxi phase were selected on the basis of the Warsaw Chopin Airport available runways. Duration of taxi phase in these cases vary between 3.1 to 11.0 minutes which is at least 58% less than in LTO test. Assuming the real taxi times change the exhaust emission results comparing to normal LTO cycle up to about 64%. The proposed methodology could be used for assessing environmental impact of air operations, which can be used to create the reports with more accurate data than with typical LTO times.

DEFINITION METHODS MECHANICAL CHARACTERISTICS OF SOUND ABSORPTION STRUCTURES

Design techniques of Sound Absorption Structures (SAS) used in aviation engines coincide, on the whole, with the techniques of designing honeycomb parts, sandwich structures that are of wide application. However, SAS have their own distinctive features. First of all, perforating of skins decreases parts’ stiffness. SAS can have different forms (three- or five-layer SAS) and differ in honeycomb height, and can also be made of different materials. The whole of that is told on effective mechanical characteristics of SAS – stiffness in a skin plane, bending stiffness, strength of joints between separate members, and others. At present, the most sound-absorbing parts are not load-bearing structures and their mechanical damages or failures are not critical. At the same time, SAS, even those made from relatively light composites, are of heavy weight, especially in turbofans, that decreases engine perfor- mance. The abovementioned requires the development of techniques for the adequate estimation of SAS mechanical characteristics. The tendency to obtain SAS properties required for designing at lower expenses results in the necessity of their analytical prediction. In connection with this, the given work presents the analytical technique for defining SAS mechanical characteristics. The techniques of averaging are used for determining the characteristics of perforated skins and honeycomb assemblies.