The main idea of the work is to create a physical model of high speed broaching heat-resistant materials is used to study the parameters of the surface layer quality. Modelling is a method of mediated cognition, in which the object under study is in some correspondence with the model, and the object-model is capable in some way or another to replace the original at some stages of the cognitive process. Physical modelling is primarily distinguished by the fact that studies are conducted on models with physical similarity, i.e. preserving completely (or at least partially) the nature of the phenomena. The work of the broach can be likened to the work of a number of planning cutter displaced relative to each other by a small amount, which is called lifting (feed per tooth). Therefore, for experimental work, a planning cutter of a special geometric was designed and manufactured – a physical model of a broach, in which geometric, mechanical and dynamic similarity is realized. The article also presents an experimental justification for the use of the created physical model in the study of the surface quality parameters of the, tab grooves of turbine and compressors disks made of heat-resistant materials.
One of the ways to reduce the adverse impact of aircraft on the environment is through the determination of the trajectory of the flight on a given route that leads to reducing fuel consumption and, consequently, emission of pollutants in jet engines exhausts. Planning a flight in terms of minimizing emissions or fuel consumption is a complex task and difficult to implement due to the conditions in which the aircraft travels, but it is possible though. It is necessary to take into account the limitations resulting from the organization of the airspace and the rules therein, as well as the current weather conditions. The weather is one of the main factors determining the amount of fuel consumed, the time and cost of a particular flight on a given route. In addition to the main parameters, such as pressure and air density, it is extremely important to determine the air temperature, as well as the wind speed and direction. The temperature affects the speed of sound, based on which it is possible to determine the Mach number for a plane flying with a given true air speed (TAS). The speed and direction of wind, on the other hand, affect the speed of the aircraft relative to the ground (velocity over ground, VOG), and thus the duration of its flight. The article describes how the developed model of emission of pollutants in the exhausts of jet bypass engines can be useful for determining the trajectory of an aircraft in its cruise phase due to the criterion of pollutants emissions minimization. An exemplary analysis was carried out for selected aircraft moving along the route adopted for the research. The analysis covered various cruising altitudes and various meteorological conditions (wind speed and direction). The obtained results are illustrated graphically and discussed.
An elevated heliport, as it has been defined by FAA (Federal Aviation Administration), is a heliport located on a rooftop or other elevated structure where the TLOF (touchdown and lift-off area) is at least 30 inches (76 cm) above the surrounding surface . One of greatest advantages of such heliports is that they require less free space, which eases its build nearby existing buildings – especially in densely built-up areas. However, design of such heliports is more complicated, than ground level ones, while one must include an aerodynamic impact of the building below the elevated heliport and surrounding buildings. The aerodynamic interference between the helicopter and the buildings may result with decline of flight safety, due to sudden decrease of thrust (when flying above the edge of building) or because of increased turbulence in windy weather, wake behind surrounding buildings causing sudden gusts etc. Moreover, oscillations of pressure caused by helicopter rotor influence on the building structure also must be taken into account due to increased wear of upper part of the building or devices mounted on its roof (for example, elevator drives). These oscillation may also cause vibrations of building’s structure, which is especially important in case of medical heliports – which are a vast majority of elevated heliports (and heliports in general) – because of strict requirements for acceptable vibration level. The article is aimed on summarize aerodynamic issues, which should be taken into account during design of elevated heliport.
Steel castings are often used in the construction of valve chambers of steam turbines. Stringent requirements are set due to the continuous operation of the material at elevated temperatures, in the order of 300°C to 600°C. The material of the valve chamber must be resistant to fatigue-creep changes as well as corrosion. This material must be also resistant to dynamic damage which occures when the turbine is starting and stopping. Dynamic damage is induced by a short-lasting but intense accumulation of localized stresses. The castings of the valve chambers of the steam turbine are usually made from the “three-component” type CrMoV-cast steel. Mentioned castings of the valve chamber are continuously subjected to high temperatures, either constant and periodically variable stresses. Due to this, the degradation process of material of the castings is taking place. It is caused by physicochemical processes such as: creep, relaxation, thermal fatigue, corrosion, erosion and changes in material properties, e.g. displacement of the critical point of brittleness. Finally, first cracks and deformations can be observed in the material during the operation. The art presents the process of revitalization technology of the steam turbine valve chamber which was subjected to long-term operation at high temperatures. The revitalization process is aimed at improving the plastic properties of the material and, as the result, extending its service life. The research presented in the article show that impact strength of the chamber material after revitalization is very high. Also the strength properties of the valve chamber, after revitalization, are high and in line with the requirements. The study show that the revitalization of the valve chamber was carried out correctly and restored the material to plastic deformation.
The article discusses assumptions for a prototype test stand designed for testing rotors in the conditions of work at their nominal speed, in particular gyrocopter and helicopter rotors. In the work presents an overview of similar solutions of test stand presented in the available literature and solutions proposed by companies, such as Swangate International or Luftfahrttechnik GmbH. Beyond these solutions the article also contains test stand used so far at the Institute of Aviation, these solutions were prepared for testing one type of rotor (for example: only for gyroplane rotors). The article provides the steps of designing a new test stand, which one of the basic assumptions is that it will be a universal test stand, giving the possibility to test different types of rotors. The article discusses two concepts of the stand with electric engine as a drive, gives the advantages and disadvantages of each concept, and indicates the selected solution. In addition to design and applied drive solution of the stand, the measuring part and data acquisition were also discussed. Moreover, the article focus on the advantages of rotor testing using the presented solution, as well as problems encountered during tests, in particular related to construction free vibrations and resonance. Vibration and resonance of the test stand are very important aspect of the entire design process, because it affects the quality and safety of the tests.
In order to increase the efficiency of jet engines hard to machine nickel-based and titanium-based alloys are in common use for aero engine components such as blades and blade integrated disks (BLISK). Electrochemical Machining (ECM) provides an economical and effective method for machining high strength and heat-resistant materials into complex shapes with high material removal rate without tool wear and without inducing residual stress. This article presents the physical and mathematical models of electrochemical shaping used in the manufacture of turbine engine parts. The modelling is based on the assumption that the multi-phase mixture filling the gap is treated as two-phase quasi-homogenous medium. The model describes the workpiece shape evolution in time, distribution the local gap size, flow parameters such as the static pressure and the velocity, temperature and void fraction as result of gas generation. The major features of the numerical computer program are briefly described with a selected example of machining a typical turbine blade. The results of computer simulation of effects of setting parameters ECM on accuracy-machined profile are discussed. The improvement of accuracy has been reached by using described sequence of ECM and Pulse ECM processes.
Digital tachographs as devices recording the work of a lorry and driver’s work are a constant factor in the work of a professional driver. It is therefore important to preserve the security of recording and storing electronic information. In this matter, cryptography also becomes an inseparable field of science. The control services set up to conduct roadside inspections do not detect all violations in the recording devices by encrypting information in information systems. One of the frequent vehicle operating parameters that can be falsified are the speed of the vehicle and its rotational speed, as well as the time and efficiency of the driver’s work. These parameters affect the amount of fuel consumption. The reduction of fuel consumption translates directly to the reduction of harmful substances emitted by the car to the environment. Variable compression engines are becoming the future of motoring in the case of internal combustion engines. It is noticeable that there are more frequent deliberate of regulations; and more violations rules concerning the proper functioning of recording devices by recording driver activity. Current methods of preventing violations are insufficient. The article points out the violations related to the actual rotational speed of the crankshaft of the internal combustion engine in relation to the vehicle speed profile, which is directly related to the fuel consumption and the emission of harmful substances. The article describes the ways to reduce fuel consumption, of which the correct driving technique is important in addition to the previously marked parameters. The factors that increase the awareness of professional drivers in the aspect of proper driving techniques are described.
In the article, changes in the properties of oils during operation were characterized. The main reason for this is the continuous aging process of the used oil caused by the interaction of oxygen contained in the air, which reacts relatively easily with hydrocarbons and the oxidation process is accelerated just by high temperature. Then the problem of microorganisms occurring in petroleum products and their effect on the properties of oils and the operation of the internal combustion engine was presented. The next part of the article presents effective microorganisms, i.e. what they are and how they work, in particular, their composition and appropriate development conditions. In addition, some of their specific applications were briefly described. In the next part of the article, the research methodology, applied oil samples with additives of effective microorganisms, both for fresh oil and used oil were described. In addition, the measuring test stand with instrumentation and measuring device was shown. The main part of the article contains the characteristics of dynamic viscosity as a function of temperature for fresh oil and used oil compared with oils with the addition of microorganisms in liquid form and ceramic tubes. The developed graphs enabled analysis of the effect of the addition of microorganisms on oil viscosity as ecological products.
Marine engines are very complex technical objects, having many important functional systems, which include, inter alia, injection system, characterized by high unreliability. In this system, there may be different types of defects (damage) that affect the engine parameters, including specific fuel consumption, as well as failures endanger the safety of the ship. The indicator diagrams and analysis of indicated parameters have limited utility in the diagnosis of damages of marine engine, although this is a method commonly used in operational practice. To achieve greater diagnostic effectiveness, when, based on indicator diagrams, are calculated and then the characteristics of heat release is analysed - net of heat release characteristics and the intensity of the heat release, it was demonstrated. This procedure is particularly effective in the diagnosis of damages of marine diesel engine injection system components. It has been shown that the characteristics of heat release contain information about the condition of the injection systems, which enable to diagnose their failures. This is shown on the example of a clogged nozzle holes (their carbonizations). The obtained results allowed selecting the diagnosis symptoms, useful in detecting these faults in the injection system, from the characteristics of heat release: net heat release (Q) and intensity of heat release (q). The object of the research was typical marine medium speed engine Sulzer A25/30.
The main idea of this article was to compare the results of new design electric brake to the older version of hydraulic brake in laboratory tests. The energy of braking should be very similar due to the same mass of the airplane. That is why the laboratory tests of both brakes were took place in the same stand. Of course, the parameters were similar but not at all. The main idea was to create the solution, which could be used in vehicle like airplane. The electric brakes could replace traditional hydraulic brake solution. The results could be interesting for every researcher who is interested in brakes. Other important idea of this article was to describe the tests of new electric brake prototype. The purpose of the tests was to check designing of electric brakes. The electric brake prototype should ensure sufficient efficiency, safety, reliability and durability during braking, which is required in certification processes and is particularly important when researching innovative solutions. It was really important to verify the design and check the parameters. Of course, there is really important to remember that in every new type of the prototype solutions there are many pros and cons, which are typical only for considered design. Nowadays every electric brake design is different because there is a lot of new concept.