A review of physical vapor deposition coatings for rolling bearings

Rolling bearings are critical in automotive engines, wind turbine drive trains, and numerous other mechanical systems. Rolling bearings can suffer from early failures, which result in high operation and maintenance costs. Surface engineering techniques, such as the application of coatings and additives for lubricants have been developed to improve the tribological performance of rolling bearings. In this article, the performance of physical vapor deposition coatings on components working under rolling/sliding contacts and rolling bearings is reviewed. The applications of physical vapor deposition coatings in the rolling bearing industry are summarized. The effects of coating thickness, coating mechanical properties, test conditions, coating bonding layer, and coating architecture on coating performance are discussed. At the end of the article, possible approaches to further improve the performance of physical vapor deposition coatings on rolling bearings are proposed.

Techno-economic analysis of the influence of different operating conditions on gas turbine centrifugal compressor set performance

In today’s world where fuel prices have increased drastically and there are great concerns about environmental issues, there is the need to properly match centrifugal compressors to their Gas Turbine (GT) drivers, so as to achieve an efficient overall package, lower turbine fuel consumption, longer time between overhauls, and most importantly, package operational flexibility in meeting alternate process conditions. This study highlights the influence of operating and environmental conditions on the overall performance of the gas turbine compressor set. GasTurb and CMap simulation softwares were employed to model and simulate the performances of the GT and centrifugal compressors respectively. The outcome of the performance plots show that at a design inlet flow volume of 15928 cubic meters per hour, the compressor required power from the gas turbine drive to transport RaNatGas is approximately 7450kW as against 7065kW and 6500kW for MaNatGas and LaNatGas mixtures respectively. Techno-economic analysis of the gas turbine compressor set shows that the fuel cost of transporting a given volume flow of RaNatGas to a specific location for a year gives about$13.5million when compared with MaNatGas and LaNatGas mixtures which cost about $13.02million and 12.3million respectively. Keywords: Natural Gas, Performance Simulations, Polytropic Efficiency, Polytropic Head, Gas Compositions

TRENDS IN THE DEVELOPMENT OF METHODS FOR DIAGNOSTICS OF THE TECHNICAL STATE OF THE BLADES OF GAS-PUMPING UNITS

Object of research: degradation processes occurring in the blades of a gas-pumping unit (GPU) during its long-term operation and cause the appearance of defects that lead to a change in their technical condition and breakage of the working blades and, as a result, to accidents. Solved problem: obtaining a method for diagnosing the GPU blades, which can be used to determine its technical condition during the GPU operation. The main scientific results: a classification of methods for diagnosing the GPU blades and their analysis was developed, according to the results of which it was established that the improvement of a new method of aerodynamic calculation of profiles relative to the GPU blades by developing mathematical models of the deformation process and flow around the GPU blades and calculation formulas for assessing their aerodynamic characteristics, will allow to simulate possible options for changing the technical state of the blades (the amount of wear of the blades, their number, deformation, etc.), to study their influence on the parameters of the oscillatory processes of the blades and to compile a dictionary (base) of diagnostic signs of their state. The use of such a base will make it possible to quickly determine the technical condition of the blades during the GPU operation and prevent the occurrence of emergency situations The area of practical use of the research results: the enterprises of the gas transmission system, which operate GPU with a gas turbine drive An innovative technological product: a method of direct aerodynamic calculation of airfoils relative to GPU blades to determine their technical condition during operation. Scope of application of the innovative technological product: gas-pumping units with a gas turbine drive with a capacity of 6.3 MW to 25.0 MW

Intelligent Diagnosis Technology of Wind Turbine Drive System based on Neural Network

The seriousness of air pollution appears to be the importance of wind energy as a non-polluting energy source. Today, the use of wind power has become a trend for new countries to develop new energy sources. Wind turbines are the key equipment for converting wind energy into electrical energy, the quality of the state directly affects the efficiency of wind power generation. Therefore, how to effectively diagnose the wind turbine drive system is the guarantee of wind power generation. This paper establishes a fault diagnosis method for wind turbine drive based on vibration characteristics, by wavelet packet decomposition of vibration signals. The feature extraction is carried out and back propagation neural network is used for classification research. Finally, the simulation results show that the recognition rate is over 90%, which verify effectiveness of the proposed method.