Удосконалення характеристик кільцевого вхідного пристрою авіаційної силової установки з гвинтовентилятором

The article considers the method of improving the characteristics of the ring inlet device, taking into account the influence of the propeller of an aircraft power plant with a turboprop engine. It is shown that increasing the total pressure loss in the inlet device by 5% increases, approximately, the specific fuel consumption by 3% and reduces engine thrust by 6%, and uneven flow at the inlet to the engine is the cause of unstable compressor of the turboprop engine. It is proposed to improve the characteristics of the input device by modifying the shape of its shell and channel. Evaluation of the influence of the shape of the shell and the channel of the annular axial VP on its main aerodynamic characteristics, taking into account the non-uniformity of the flow on the fan in the calculated mode of operation of the SU is carried out by calculating the full pressure recovery factor. The object of the study is an annular axial input device in front of which is a coaxial fan turboprop fan. The process of modeling the influence of the shape of the shell and the channel on the recovery factor of total pressure, circular and radial non-uniformity of the flow through the input device is implemented in the software system of finite element analysis ANSYS CFX. Geometric models of coaxial screw fan, fairing and inlet device are built in ANSYS SpaceClaim and transferred using the built-in import function in ANSYS Workbench. Block-structured grid models of air propellers of the first and second rows of the fan in the amount of 1.9 million, fairing and inlet device, in the amount of 3.9 million, are built in the ANSYS TurboGrid environment. The standard Stern (Shear Stress Transport) Gamma Theta Transition was used to close the Navier-Stokes equation system. Based on the results of mathematical modeling of flow in coaxial fans and subsonic ring inlet device on the maximum cruising mode of the turboprop engine, the full pressure recovery factor is calculated and it is established that the most influential factor that increases its full pressure recovery factor.

A Resonant Pressure Microsensor with Temperature Compensation Method Based on Differential Outputs and a Temperature Sensor

This paper presents the analysis and characterization of a resonant pressure microsensor, which employs a temperature compensation method based on differential outputs and a temperature sensor. Leveraging a silicon-on-insulator (SOI) wafer, this microsensor mainly consists of a pressure-sensitive diagram and two resonant beams (electromagnetic driving and electromagnetic induction) to produce a differential output. The resonators were vacuum packaged with a silicon-on-glass (SOG) cap using anodic bonding and the wire interconnection was realized by sputtering an Au film on highly topographic surfaces using a hard mask. After the fabrication of the resonant pressure microsensor, systematic experiments demonstrated that the pressure sensitivity of the presented microsensor was about 0.33 kPa/Hz. Utilizing the differential frequency of the two resonators and the signal from a temperature sensor to replace the two-frequency signals by polynomial fitting, the temperature compensation method based on differential outputs aims to increase the surface fitting accuracy of these microsensors which have turnover points. Employing the proposed compensation approach in this study, the errors were less than 0.02% FS of the full pressure scale (a temperature range of −40 to 85 °C and a pressure range of 200 kPa to 2000 kPa).

Structured Response Plan After a Ground Movement Event

The vast majority of buried pipelines are not designed to accommodate significant localized ground movement caused by landslides, earthquakes, or subsidence/settlement. When a ground movement event occurs along the ROW of a buried pipeline, it is imperative that the pipeline operator determine whether the ground movement is a threat to pipeline integrity to protect those responding to the event, those living near the affected ROW, and the environment. This paper covers the development of a response plan that provides guidance to pipeline operators responding to a ground movement event while considering the unique conditions associated with such events. The response plan covers some critical decisions after an event, including, but not limited to (1) whether the event affects the pipeline, the local ROW, or those living adjacent to the ROW, (2) control of flow, i.e., the need for shutdown or pressure reduction, and (3) work needed to return the line to full-pressure service. The overall response plan is presented in three main phases: • Phase 1: Immediate Response, • Phase 2: Follow-on Assessment and Actions, and • Phase 3: Long-term Management. The structured response plan and associated guidance are presented in a self-contained stand-alone document available from PRCI. Parts of the document or the entire document can be adopted by operators, depending on the extent of existing procedures an operator may have. Alternatively, company-specific information and procedures can be added to the document to form a company-specific SOP.

FEATURES OF THE INITIAL STAGE OF FORMATION OF FAST CORONAL MASS EJECTION ON FEBRUARY 25, 2014

We have analyzed the fast coronal mass ejection (CME) that occurred on February 25, 2014. The analysis is based on images taken in the 131, 211, 304, and 1700 Å UV channels of the SDO/AIA instrument and from observations obtained in the Hα line (6562.8 Å) with the telescopes of the Teide and Big Bear Observatories. The February 25, 2014 CME is associated with the ejection and subsequent explosive expansion of the magnetic flux rope, which appeared near the solar surface presumably due to the tether-cutting magnetic reconnection. The impulse of full pressure (thermal plus magnetic) resulting from such an “explosion” acts on the overlying coronal arcades, causing them to merge and form an accelerated moving frontal structure of the CME. This pressure impulse also generates a blast collisional shock wave ahead of the CME, whose velocity decreases rapidly with distance. At large distances R>7R₀ (R₀ is the solar radius) from the center of the Sun in front of the CME, a shock wave of another type is formed — a “piston” collisional shock wave whose velocity varies little with distance. At R≥15R₀, there is a transition from a collisional to a collisionless shock wave.

FEATURES OF THE INITIAL STAGE OF FORMATION OF FAST CORONAL MASS EJECTION ON FEBRUARY 25, 2014

We have analyzed the fast coronal mass ejection (CME) that occurred on February 25, 2014. The analysis is based on images taken in the 131, 211, 304, and 1700 Å UV channels of the SDO/AIA instrument and from observations obtained in the Hα line (6562.8 Å) with the telescopes of the Teide and Big Bear Observatories. The February 25, 2014 CME is associated with the ejection and subsequent explosive expansion of the magnetic flux rope, which appeared near the solar surface presumably due to the tether-cutting magnetic reconnection. The impulse of full pressure (thermal plus magnetic) resulting from such an “explosion” acts on the overlying coronal arcades, causing them to merge and form an accelerated moving frontal structure of the CME. This pressure impulse also generates a blast collisional shock wave ahead of the CME, whose velocity decreases rapidly with distance. At large distances R>7R₀ (R₀ is the solar radius) from the center of the Sun in front of the CME, a shock wave of another type is formed — a “piston” collisional shock wave whose velocity varies little with distance. At R≥15R₀, there is a transition from a collisional to a collisionless shock wave.

A theoretical model for coal swelling induced by gas adsorption in the full pressure range

The phenomenon of coal swelling caused by gas adsorption is well known. For Enhanced Coal Bed Methane Recovery and carbon storage, coal swelling induced by gases adsorption may cause significant reservoir permeability change. In this paper, based on the assumption that the surface energy change caused by adsorption is equal to the change in elastic energy of the coal matrix, a theoretical model is derived to describe coal swelling induced by gas adsorption in the full pressure range. The Langmuir constant, coal density, solid elastic modulus, and Poisson’s ratio are required in this model. These model parameters are easily obtained through laboratory testing. The developed model is verified by available experimental data. The results show that the presented model shows good agreement with the experimental observations of swelling. The model errors are within 14% for pure gas, and within 20% for mixed gas. It is shown that this model is able to describe coal swelling phenomena for full pressure range and different gas type including pure gas and mixed. In addition, it is also shown that the errors of the presented model and the Pan’s model are almost the same, but the presented model is solved more easily.

THE ANALYSIS AND EXPERIMENTAL ASSESSMENT OF LOCAL HYDRAULIC LOSSES IN THE BALL CRANE UNDER REGULATION

In the article there is given an analysis and experimental results of researches of local hydraulic losses in a ball valve at regulation, there is given the dependence of coefficients of local resistances of the ball valve of Bugatti Dy – 20 mm from Reynolds number ζ = f(Re) at various angles of rotation of the crane α. Experimental values of local resistivity coefficients of a ball crane for rotation angles α in the Reynolds number range Re =1,8 ×104 ¸ 3,1×104 and values for full-pass control locking ball cranes with a floating plug and a plug fixed in supports Dy from 50 to 1400mm at Reynolds numbers Re 2 ×104, as well as with reference literature data for the gate were compared (ball) with a spherical disk located in a straight pipe network at Reynolds numbers Re >104. The paper clarifies and shows the numerical picture of velocity and full pressure distribution in the ball valve under investigation. The empirical dependence of values of resistance coefficients of the ball crane at different values of crane rotation angle ζ = f(α) in auto-model resistance region is presented.

Влияние способа подачи воздуха на параметры прецессирующего вихревого жгута в гидродинамической вихревой камере

The effect of the method of gas-phase injection into a swirled fluid flow on parameters of a precessing vortex core is studied experimentally. Conditions of the appearance of the vortex-core precession effect were modeled in a hydrodynamic sudden expansion vortex chamber. The dependences of the vortexcore precession frequency, flow-pulsation level, and full pressure differential in the vortex chamber on the consumption gas content in the flow have been obtained. The results of measurements permit one to determine optimum conditions for the most effective control of vortex-core precession.