Experimental Investigation of Leakage in the Modified Revolving Vane Expander

This study focuses on the leakage characteristics of a modified revolving vane expander (M-RVE) using both static and dynamic leakage analysis. The no-expansion scenario showed a maximum volumetric efficiency of 18.7% was achieved at 5.5 bar(g) suction pressure, showing the severity of internal leakages. The blocker angle study demonstrated the importance of the correct opening-angle selection to avoid under or over-expansion. The maximum volumetric efficiencies for opening angles of 94 deg and 145 deg were 2.8% and 8.3%, respectively, at suction and discharge pressures of 6.5 bar(g) and 1 atm, respectively. The static leakage test demonstrated that the M-RVE housing was properly sealed, and the observed leakage in the dynamic test was mostly due to internal leakages. The results showed that the leakages through the radial clearance, endface, and vane side gaps make up 54%, 33%, and 8.5% of the overall leakage. Comparison between the theoretical and experimental data of the leakages through the radial clearance gap showed significant deviations at higher suction pressures. The reasons are thought to be due to the shafts' tilt, and the cylinder and rotor head deflections. It is believed that the deflection of the shaft created new leakage paths or changed the geometry of the current paths.

Numerical Investigation of an Optimized Rotor Head Fairing for the RACER Compound Helicopter in Cruise Flight

The present work is part of the Clean Sky 2 project Full-Fairing Rotor Head Aerodynamic Design Optimization (FURADO), which deals with the aerodynamic design optimization of a full-fairing rotor head for the Rapid And Cost-Effective Rotorcraft (RACER) compound helicopter. The rotor head is a major drag source and previous investigations have revealed that the application of rotor head fairings can be an effective drag reduction measure. As part of the full-fairing concept, a new blade-sleeve fairing was aerodynamically optimized for cruise flight. Within this publication, the newly developed blade-sleeve fairing is put to test on an isolated, five-bladed rotor head and compared to an already existing reference blade-sleeve fairing, which was developed at Airbus Helicopters. Numerical flow simulations are performed with ANSYS Fluent 2019 R2 considering a rotating rotor head with cyclic pitch movement. The aerodynamic forces of the isolated rotor head are analyzed to determine the performance benefit of the newly developed blade-sleeve fairing. A drag reduction of 4.7% and a lift increase of 20% are obtained in comparison to the Airbus Helicopters reference configuration. Furthermore, selected surface and flow field quantities are presented to give an overview on the occurring flow phenomena.

Rotor head shape optimization in a salient pole synchronous machine

The purpose of this paper is to optimize the topology of the rotor head in a Salient Pole Synchronous Generator to maximize the magnetic flux in the stator yoke and in the air gap. The generator is modelled using FE method, and the ON-OFF method is used to manage the optimization domain. Genetic Algorithm is used to find the optimal solution for the problem. The resulting topology and convergence graphs are also presented, and the results are discussed.

Performance improvement of a compound helicopter rotor head by aerodynamic design optimisation of a blade-sleeve fairing

ABSTRACTWithin the present publication, the rotor head of a compound helicopter known as Rapid And Cost-Effective Rotorcraft (RACER) is investigated. In particular, the aerodynamic design optimisation of the RACER blade-sleeve fairings (BSFs) is conducted. For this purpose, an isolated rotor head is generated featuring a full-fairing beanie, the BSF and a truncated rotor blade (RB). Moreover, a single RB is investigated at two different azimuthal rotor positions, which correspond to the advancing and the retreating RB case. For this purpose, an averaged circumferential velocity is determined in the blade-sleeve region and superposed with the RACER cruise speed in order to estimate the prevailing flow conditions. The automated aerodynamic design optimisation is performed by means of a previously developed optimisation tool chain. A global multi-objective genetic optimisation algorithm is applied for the given problem. During preliminary work, a 2D aerodynamic design optimisation of selected blade-sleeve sections was conducted. These optimised aerofoils represent the design variables for the current optimisation problem. The shape modification of the 3D fairing is realised by exchanging specific aerofoils at certain spanwise sections.

Numerical CFD Analysis of an Aerodynamic Head Cover of a Rotorcraft Motor

Autogyros can become an alternative for the use of rotorcrafts in various fields of life, including agroforestry. They have better economic performance than helicopters, owing to, among other things, the presence of a bearing rotor. Most autogyros also have other advantages in terms of no need for the compliance with stringent regulatory regulations – with respect to new constructions, lower combustion, noise and emissions of toxic elements. The cover of the bearing rotor head is an important element of rotorcrafts, which demonstrates that aerodynamics plays an important role in aerodynamic designs. Therefore, in this article, air flow model testing is carried out for two types of the bearing rotor blades of an autogyro with and without a cover using the ANSYS Fluent program. An aerodynamic drag analysis was also performed.

The analysis of influence of parameters of a cutting instrument and cutting modes on quality and power indicators in the conditions of roundup of logs

В сравнении с другими технологическими операциями оцилиндровка бревен самая ответственная, трудоемкая и энергоемкая технологическая операция, определяющая внешний вид готового изделия и его качество. В настоящее время в ведущих в этой области странах постоянно совершенствуются процессы оцилиндровки бревен, режимы обработки и режущие инструменты. В связи с этим исследование влияния параметров режущего инструмента и режима резания на мощностные и качественные показатели оцилиндровки бревен, следует считать актуальными. В задачи экспериментальных исследований входило изучение влияния параметров резцов и режима резания на мощностные и качественные показатели оцилиндровки бревен резанием; установление связи характера стружкообразования. В настоящей статье приведены результаты экспериментальных опытов и методика их выполнения, описана конструкция опытного узла резания, установленного на суппорте экспериментальной установки, приведены графические схемы и технические характеристики. Данная конструкция обеспечивает четыре степени свободы для резца, что позволяет ориентировать лезвие в пространстве и получать углы, необходимые для проведения экспериментов. Державка имеет два поворотных плоских шарнира с лимбами, а также устройство для поворота режущей кромки на требуемые углы скоса и положения резца. При проведении опытов в соответствии с методической сеткой определялась зависимость мощности на резание от основных режимных и инструментальных факторов при оцилиндровке сосновых и еловых бревен с влажностью 30%. Опыты выполнялись на основе методики однофакторного эксперимента. Результаты подвергались статистической обработке, в последующем обработка полученных данных производилась графическим методом с выявлением степенных зависимостей. На основе зависимостей мощности резания от основных факторов авторами были получены частные и общие зависимости мощности резания. В режущей охватывающей головке позиционного оцилиндровочного станка должны быть две группы ножей: ножи для черновой обработки и ножи для чистовой обработки. Основными доминирующими факторами, влияющими на мощность резания при оцилиндровке бревен черновыми резцами, являются подача на резец, главный угол в плане, угол скоса резца. Для чистовых резцов при равных прочих условиях доминирующим фактором является угол наклона режущей кромки резца. С увеличением подачи на резец в пределах от 0,2 до 0,6 мм/об, мощность резания при оцилиндровке черновыми резцами возрастает. С увеличением главного в плане чернового резца мощность резания уменьшается. С увеличением угла скоса чернового резца мощность резания возрастает. Для обеспечения нормальных условий оцилиндровки бревен многорезцовым инструментом в виде охватывающей роторной головки, в практике на позиционных станках рекомендуются следующие значения для черновых резцов: Sz = S0 = 0,4÷0,6 мм/об; φ = 50÷60°; ε = 15÷20°, резцы острые (ρ = 10–15 мкм), материал резцов – быстрорежущая сталь P9, P18. Резцы: цельные или оснащенные пластинками из быстрорежущей стали. Для обеспечения нормальных условий резания и требуемого качества поверхности обработки угол наклона чистовых острых резцов рекомендуется в пределах 20–30°. In comparison with other technological operations roundup of logs the most responsible, heavy and power-intensive technological work defining appearance of finished product and its quality. Now in the countries conducting in this area processes of roundup of logs, processing conditions and cutting instruments constantly are improved. In this regard a research of influence of parameters of a cutting instrument and cutting mode on power and quality indicators of roundup of logs, it is necessary to consider urgent. Entered problems of the pilot studies: studying of influence of parameters of cutters and a cutting mode on power and quality indicators of roundup of logs cutting; establishment of communication of character of a cutting. Results of the experimental experiences and technique of their realization are given in this article, the design of experienced knot of the cutting established on a support of the pilot unit is described graphic schemes and principal specifications are provided. This design provides four degree of freedoms for a cutter that allows to focus an edge in space and to receive corners necessary for carrying out experiments. The chuck has two rotary flat hinges with limbuses, and also the device for turn of a trimming blade on the required rake angles and provisions of a cutter. When carrying out experiences according to a methodical grid dependence of power was defined on cutting from the major regime and instrumental factors at roundup of pine and fir-tree logs with humidity of 30%. Experiences were carried out on the basis of a technique of a one-factorial experiment. Results were exposed to statistical processing, in subsequent processing of the obtained data was made by a graphic method with identification of exponential laws. On the basis of dependences of power of cutting on major factors we received private and common dependences of power of cutting. In the cutting covering head of the positional machine, there have to be two groups of knives: knives for roughing and knives for smoothing. The major dominating factors influencing cutting power at roundup of logs draft cutters are: giving on a cutter, the main corner in the plan, a cutter rake angle. For fair cutters under equal other conditions the dominating factor is the slope angle of a trimming blade of a cutter. With increase in giving at a cutter ranging from 0,2 to 0,6 mm/cycle, cutting power at roundup by draft cutters increases. With increase in the main thing in respect of a draft cutter the power of cutting decreases. With increase in a rake angle of a draft cutter the power of cutting increases. For providing standard conditions of roundup of logs with the many knifes tool in the form of the covering rotor head, in practice on positional machines the following values for draft cutters are recommended: Sz = S0 = 0,4÷0,6 mm/cycle; φ = 50÷60 °; ε = 15÷20°, cutters sharp (ρ = 10–15 microns), material of cutters – quick cutting steel (R9, R18). Cutters: integral or equipped with plates from quick cutting steel. For providing standard conditions of cutting and the required quality of a surface of processing, the slope angle of fair sharp cutters is recommended within 20÷30°.

The Analysis of Electrical Energy Consumption of the Impact Screwdriver During Assembly of Fixed Threaded Joints

The paper deals with the possibilities of reducing the consumption of electrical energy of the impact screwdriver during the assembly of fixed threaded joints. The recommendations related to a decrease in electrical energy consumption would allow reducing product costs but so far there have been no such recommendations from the producers of the tool as to the effective operating regimes of the impact screwdrivers in relation to electrical energy consumption and necessary tightening moment of the nut. The aim of the study is to find out the economical operating mode of the electrical impact screwdriver when assembling fixed threaded joints. By varying the set speed of the rotor head and working time of the impact mechanism, there is an opportunity to determine electrical energy consumption of the tool for the given tightening moment. The results of the experiment show that at the same tightening moment obtained the electrical energy consumption of the impact screwdriver is less at a higher starting set speed of the rotor head but shorter operating time of the impact mechanism than at a lower speed of the rotor head and longer operating time of the impact mechanism.