Tables of geometric, high-speed and energy characteristics for the bottom parts of a tornado

2018 ◽  
pp. 63-70
Author(s):  
Ирина Юрьевна Крутова
Keyword(s):  
Kinetic Energy ◽  
Rotational Motion ◽  
High Speed ◽  
Natural Phenomenon ◽  
Dynamic Parameters ◽  
Bottom Part ◽  
Energy Characteristics ◽  
Gas Dynamic ◽  
Destruction Zone ◽  
Object Of Study

В настоящей работе при заданном в таблице Фудзиты значении ширины полосы разрушений для всех торнадо установлены два внешних радиуса притока воздуха в придонную часть торнадо: <sub>in</sub><sub>1 </sub> и r<sub>in</sub><sub>2</sub>. Первый из этих радиусов <sub>in</sub><sub>1 </sub> такой, что кинетическая энергия вращательного движения построенного потока составляет половину всей его кинетической энергии. При втором радиусе r<sub>in</sub><sub>2</sub> кинетическая энергия всего потока становится равной кинетической энергии самого слабого торнадо, при котором имеют место разрушения. Знание значений этих радиусов позволит более надежно прогнозировать возникновение торнадо. The natural phenomenon of a tornado, known for its destructive power, is an object of study of many scientists. The available part of the data of field observations of this natural phenomenon is systematized and collected in the so-called Fujita scale. In particular, it indicates the width of the fracture band for tornadoes of different intensity, and only the values of the maximum wind speed are given from the gas dynamic parameters. Bautin S.P. proposed and justified the scheme of occurrence and functioning of natural ascending swirling flows of the tornado and tropical cyclones. Based on both this scheme and the data of the Fujita scale, the external radii of air inflow in the near-bottom parts of tornadoes of various intensities are established and the gas dynamic parameters of these flows are calculated. It turned out that in the case of the lowest intensity from the Fujita scale, the kinetic energy of the rotational motion of the air is half of the entire kinetic energy of the flow in the bottom part. As tornado intensity increases, the kinetic energy of rotational motion becomes the more prominent part of the total kinetic energy of the flow. In this paper, given the Fujita value of the width of the destruction zone for all tornadoes along with the two external radii of air inflow into the bottom part of the tornado are established as r<sub>in</sub><sub>1 </sub> and r<sub>in</sub><sub>2</sub>. The first of these radii, namely r<sub>in</sub><sub>1 </sub>, denotes the radius at which the kinetic energy of the rotational motion of the constructed stream is half of all the kinetic energy of this stream. The second one denoted as r<sub>in</sub><sub>2</sub>, is the radius at which the kinetic energy of the entire stream becomes equal to the kinetic energy of the weakest destructive tornado. Knowing the values of these radii allows reliable predicting the origin of the tornado.

scholarly journals NUMERICAL CALCULATIONS OF ENERGY CHARACTERISTICS FOR SIMULATION THE STEADY-STATE OUTPUT OF AN ARTIFICIAL TORNADO

2018 ◽  
pp. 84-92
Author(s):  
R. E. Volkov ◽  
A. G. Obukhov ◽  
N. V. Terekhova
Keyword(s):  
Steady State ◽  
Kinetic Energy ◽  
Rotational Motion ◽  
Numerical Experiments ◽  
Swirling Flow ◽  
Numerical Calculations ◽  
Stationary Mode ◽  
Energy Characteristics ◽  
Acceleration Time ◽  
Mode Of Operation

The article deals with the results of numerical experiments simulating various ways of reaching the steadystate regime of an ascending swirling air flow in an artificially created tornado. The values of the total kinetic energy and kinetic energy of the rotational motion of the flow are calculated, and the functional dependences of its energy characteristics on time are found. In addition, the acceleration time is determined for various methods of outputting a swirling flow to a stationary mode of operation.

Actual issues of systematization of scientific knowledge on the conditions of shot in the forensic ballistics

2020 ◽  
Vol 2020 (3) ◽  
pp. 164-169
Author(s):  
Igor' Latyshov ◽  
Fedor Samuylenko
Keyword(s):  
Scientific Knowledge ◽  
Communication Systems ◽  
Production Method ◽  
Natural Phenomenon ◽  
Projectile Energy ◽  
Energy Characteristics ◽  
Shot Classification ◽  
Forensic Ballistics

In this research, there was considered a challenge of constructing a system of scientific knowledge of the shot conditions in judicial ballistics. It was observed that there are underlying factors that are intended to ensureits [scientific knowledge] consistency: identification of the list of shot conditions, which require consideration when solving expert-level research tasks on weapons, cartridges and traces of their action; determination of the communication systems in the course of objects’ interaction, which present the result of exposure to the conditions of the shot; classification of the shot conditions based on the grounds significant for solving scientific and practical problems. The article contains the characteristics of a constructive, functional factor (condition) of weapons and cartridges influence, environmental and fire factors, the structure of the target and its physical properties, situational and spatial factors, and projectile energy characteristics. Highlighted are the forms of connections formed in the course of objects’ interaction, proposed are the author’s classifications of forensically significant shooting conditions with them being divided on the basis of the following criteria: production from the object of interaction, production from a natural phenomenon, production method, results weapon operation and utilization, duration of exposure, type of structural connections between interaction objects, number of conditions that apply when firing and the forming traces.

Synthesis and Analysis of a Combined Magnetic and Gas Dynamic Suspension for a Model Range of New-Generation High-Speed Micro Gas Turbine Power Units

2021 ◽  
pp. 5-17
Author(s):  
Sergey A. GANDZHA ◽  
◽  
Nikolay I. NEUSTROEV ◽  
Pavel A. TARANENKO ◽  
◽  
...  
Keyword(s):  
Gas Turbine ◽  
High Speed ◽  
Turbine Unit ◽  
Electrical Machine ◽  
Gas Turbine Unit ◽  
Micro Gas Turbine ◽  
Gas Dynamic ◽  
Study Results ◽  
Generator Design ◽  
New Generation

The modern power industry is characterized by intense development of distributed generation, with which numerous sources of different capacities are connected into a single network. This makes it possible to improve the reliability of the entire system, since the probability of several sources to fail simultaneously is quite low. Electric generation based on high-speed gas turbine units accounts for a significant share in the overall balance, due to which scientific research and new engineering solutions in this area are important and relevant. An innovative design of a high-speed gas turbine unit based on a switched axial generator is proposed. This electrical machine has a diamagnetic armature, which eliminates magnetic losses, due to which better efficiency of the power unit is achieved and its design is simplified. The high speed of rotation and the presence of critical resonant rotor speeds generated the need to adopt appropriate engineering decisions in regard of its supports. A combined suspension involving the use of magnetic and gas-dynamic bearings is proposed. The magnetic bearings support the gas turbine unit operation at low speeds during its acceleration, and the gas-dynamic bearings support its operation at high nominal speed. The generator design and the combined suspension layout are shown. The numerical analyses of magnetic and gas-dynamic bearings for a gas turbine unit for a capacity of 100 kW and rotation speed of 70 000 rpm are given. The study results can be used for a series of gas turbine units with capacities ranging from 10 to 500 kW. In our opinion, this concept is competitive with modern analogs with a radial generator design.

A New Method of Torque Compensation for High Speed Indexing Cam Mechanism

1999 ◽  
Vol 121 (2) ◽  
pp. 319-323 ◽  
Author(s):  
Teng Guilan ◽  
Fu Haibo ◽  
Zhou Weiyi
Keyword(s):  
Kinetic Energy ◽  
High Speed ◽  
Output Shaft ◽  
New Method ◽  
Linkage Mechanism ◽  
Energy Fluctuation ◽  
Positioning Accuracy ◽  
Input Shaft ◽  
Cam Mechanism

Severe vibration and poor positioning accuracy may occur in an indexing cam mechanism operating at a high speed. Torque fluctuation of the input shaft and the resulting fluctuation of kinetic energy of the mechanism may be the major cause of the vibration. In this paper a method is proposed to minimize the fluctuation by using a so-called “speed-varying flywheel” that produces an opposite kinetic energy fluctuation that can counteract the effect of the energy fluctuation. The flywheel is installed on the output shaft of an additional cam-linkage mechanism. The parameter of the cam-linkage mechanism is optimized. An example is given to demonstrate the effectiveness of this method.

CFD Investigation of the Flow of Trailing Edge Cooling Slots

2018 ◽  
Author(s):  
Y. Jiang ◽  
N. Gurram ◽  
E. Romero ◽  
P. T. Ireland ◽  
L. di Mare
Keyword(s):  
Mach Number ◽  
Kinetic Energy ◽  
Flow Separation ◽  
Film Cooling ◽  
High Speed ◽  
Turbine Blades ◽  
Cross Flow ◽  
Turbulent Energy ◽  
Trailing Edge ◽  
Flow Interactions

Slot film cooling is a popular choice for trailing edge cooling in high pressure (HP) turbine blades because it can provide more uniform film coverage compared to discrete film cooling holes. The slot geometry consists of a cut back in the blade pressure side connected through rectangular openings to the internal coolant feed passage. The numerical simulation of this kind of film cooling flows is challenging due to the presence of flow interactions like step flow separation, coolant-mainstream mixing and heat transfer. The geometry under consideration is a cutback surface at the trailing edge of a constant cross-section aerofoil. The cutback surface is divided into three sections separated by narrow lands. The experiments are conducted in a high speed cascade in Oxford Osney Thermo-Fluids Laboratory at Reynolds and Mach number distributions representative of engine conditions. The capability of CFD methods to capture these flow phenomena is investigated in this paper. The isentropic Mach number and film effectiveness are compared between CFD and pressure sensitive paint (PSP) data. Compared to steady k–ω SST method, Scale Adaptive Simulation (SAS) can agree better with the measurement. Furthermore, the profiles of kinetic energy, production and shear stress obtained by the steady and SAS methods are compared to identify the main source of inaccuracy in RANS simulations. The SAS method is better to capture the unsteady coolant-hot gas mixing and vortex shedding at the slot lip. The cross flow is found to affect the film significantly as it triggers flow separation near the lands and reduces the effectiveness. The film is non-symmetric with respect to the half-span plane and different flow features are present in each slot. The effect of mass flow ratio (MFR) on flow pattern and coolant distribution is also studied. The profiles of velocity, kinetic energy and production of turbulent energy are compared among the slots in detail. The MFR not only affects the magnitude but also changes the sign of production.

APPLICATION OF THE IMPLICIT METHOD OF CHARACTERISTICS ON A REGULAR GRID FOR SOLVING THE GAS-DYNAMIC PROBLEMS

2021 ◽  
pp. 80-92
Author(s):  
A.M. Lipanov ◽  
Keyword(s):  
Solid Propellant ◽  
Method Of Characteristics ◽  
Rocket Engine ◽  
Second Order ◽  
Implicit Method ◽  
Dynamic Parameters ◽  
Time Layer ◽  
Engine Operation ◽  
Order Of Accuracy ◽  
Gas Dynamic

In this work, an implicit method is proposed to numerically solve a system of the onedimensional nonstationary equations of gas dynamics transformed by the method of characteristics. Internal points of the channel for a solid-propellant charge are considered at a preignition period of the solid-propellant rocket engine operation. The use of the implicit method makes it possible to calculate the values of gas-dynamic parameters at nodal points of the regular coordinate grid. Calculations of the gas-dynamic parameters both when integrating over time and along the spatial coordinate are performed with the second order of accuracy. Both subsonic and supersonic flows are studied. It is shown that, when predicting the expected pressure value during the transition from one time layer to another with the second order of accuracy, the twenty-fold efficiency of the implicit method is achieved in comparison with the explicit difference method. The trial calculation is performed.

scholarly journals Research into Correlation between the Lubrication Mode of Contact Surfaces and Dynamic Parameters of Turbo-Generator Transmissions

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Marek Kočiško ◽  
Petr Baron ◽  
Monika Telíšková ◽  
Jozef Török ◽  
Anna Bašistová
Keyword(s):  
Acoustic Emission ◽  
High Frequency ◽  
High Speed ◽  
Oil Quality ◽  
The State ◽  
Dynamic Parameters ◽  
High Frequency Vibration ◽  
Turbo Generator ◽  
Friction Mode ◽  
Contact Surfaces

The paper presents the results of an experimental study aimed at assessing the correlation between the measurement of dynamic parameters (vibration, high-frequency vibration, and acoustic emission) and the analysis of friction mode and the state of lubrication of the contact surfaces of two gearboxes in the turbo-generator assembly (high-speed single-body steam turbine—gearbox—generator) with the transmission power of no more than 50 MW. The analysis confirmed the assumption of a significant correlation of the monitored high-frequency vibration signal with the unsatisfactory engagement of the gear teeth. Through vibration analysis, an increased level of the tooth vibration component and vibration multiples with increased acoustic emission were identified in gearbox operation. The gear oil of one of the gearboxes examined showed a loss of additive elements in the real operation of the contact surfaces of the teeth engagement. The trend analysis confirmed the complexity of the monitored transmission operation in terms of the friction mode and the influence of the oil quality on the state of the tooth flank microgeometry.

Flow Visualization and Forces From a Squeeze Film Damper Operating With Natural Air Entrainment

2003 ◽  
Vol 125 (2) ◽  
pp. 325-333 ◽  
Author(s):  
Luis San Andre´s ◽  
Sergio E. Diaz
Keyword(s):  
High Speed ◽  
Air Entrainment ◽  
Squeeze Film ◽  
Natural Phenomenon ◽  
Squeeze Film Damper ◽  
Feed Pressure ◽  
Video Recordings ◽  
Free Air ◽  
Through Flow ◽  
Discharge Operation

Measurements of dynamic film pressures and high-speed photographs of the flow field in an open-ended Squeeze Film Damper (SFD) operating with natural free air entrainment are presented for increasing whirl frequencies (8.33–50 Hz), and a range of feed pressures to 250 kPa (37 psig). The flow conditions range from lubricant starvation (air ingestion) to a fully flooded discharge operation. The test dynamic pressures and video recordings show that air entrainment leads to large and irregular gas fingering and striation patterns. This is a natural phenomenon in SFDs operating with low levels of external pressurization (reduced lubricant through flow rates). Air ingestion and entrapment becomes more prevalent as the whirl frequency raises, and increasing the feed pressure aids little to ameliorate the loss in dynamic forced performance. As a result of the severity of air entrainment, experimentally estimated damping forces decrease steadily as the whirl frequency (operating speed) increases.

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