scholarly journals Development of Hydraulic Turbodrills for Deep Well Drilling

2021 ◽  
Vol 11 (16) ◽  
pp. 7517
Author(s):  
Mikhail V. Dvoynikov ◽  
Dmitry I. Sidorkin ◽  
Andrey A. Kunshin ◽  
Danil A. Kovalev
Keyword(s):  
High Speed ◽  
Drilling Fluid ◽  
Hydraulic Turbine ◽  
Maximum Power ◽  
Rotor Blades ◽  
Stable Operation ◽  
Support Unit ◽  
Spindle Shaft ◽  
Fold Reduction ◽  
Foreign Analog

The article discusses the possibility of improving the design of the turbine of a hydraulic drilling machine for drilling wells in very hard rocks and at considerable depths (5000–12,000 m). The analysis of the results of studies on the technical and technological characteristics of downhole drilling motors showed that it is impossible to ensure stable operation due to the limitation on the operating temperature, while with an increase in the flow rate of the drilling fluid, they do not provide the required power on the spindle shaft, and cannot reach high-speed drilling. In such conditions, turbodrills with a significant change in the profile of the stator and rotor blades and a reinforced support unit are most suitable. The paper presents an invariant mathematical model, which made it possible to determine the optimal geometric parameters based on preselected boundary conditions and the main performance characteristics of the turbine being developed. The results obtained were tested by the finite element method, which showed a convergence of 12.5%. At the same time, zones with the lowest and highest flow rates were identified. Additionally, this paper presents a comparative analysis of the obtained hydraulic turbine with turbodrills of the TSSH-178T and Neyrfor TTT 2 7/8 brands. In comparison with the domestic turbodrill, the developed turbine design shows a 13-fold reduction in its length and a 3-fold reduction in torque, provided that the maximum power is increased by 1.5 times. In comparison with the foreign analog, there is a decrease in length by 8.5 times, an increase in torque by 5 times, and in maximum power by 6.5 times.

Stable operation of multiple-lateral-mode ridge-waveguide lasers for high-speed printing

1997 ◽  
Vol 33 (3) ◽  
pp. 214
Author(s):  
R. LaComb ◽  
D.K. Wagner ◽  
L. DiMarco ◽  
J. Connolly
Keyword(s):  
High Speed ◽  
Ridge Waveguide ◽  
Stable Operation ◽  
Waveguide Lasers ◽  
Lateral Mode ◽  
Ridge Waveguide Lasers

Stability of Milling Operations With Asymmetric Cutter Dynamics in Rotating Coordinates

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Alptunc Comak ◽  
Orkun Ozsahin ◽  
Yusuf Altintas
Keyword(s):  
Time Domain ◽  
Machine Tools ◽  
High Speed ◽  
End Mill ◽  
Spindle Shaft ◽  
Milling Operations ◽  
Stability Model ◽  
Principal Directions ◽  
The Stability ◽  
Rotating Coordinates

High-speed machine tools have parts with both stationary and rotating dynamics. While spindle housing, column, and table have stationary dynamics, rotating parts may have both symmetric (i.e., spindle shaft and tool holder) and asymmetric dynamics (i.e., two-fluted end mill) due to uneven geometry in two principal directions. This paper presents a stability model of dynamic milling operations with combined stationary and rotating dynamics. The stationary modes are superposed to two orthogonal directions in rotating frame by considering the time- and speed-dependent, periodic dynamic milling system. The stability of the system is solved in both frequency and semidiscrete time domain. It is shown that the stability pockets differ significantly when the rotating dynamics of the asymmetric tools are considered. The proposed stability model has been experimentally validated in high-speed milling of an aluminum alloy with a two-fluted, asymmetric helical end mill.

Modeling and Analysis of Grid-Connected Inverter for PV Generation

2013 ◽  
Vol 760-762 ◽  
pp. 451-456 ◽  
Author(s):  
Neng Cao ◽  
Ya Jun Cao ◽  
Jiao Yu Liu
Keyword(s):  
Control System ◽  
Power Quality ◽  
High Speed ◽  
Control Algorithm ◽  
Maximum Power ◽  
Maximum Power Point ◽  
Incremental Conductance ◽  
Conductance Method ◽  
Power Point ◽  
Pv Generation

In order to improve the efficiency of photovoltaic generation as well as the power quality, grid-connected inverters for PV generation research was carried out for photovoltaic maximum power point tracking. Based on some current studies on the incremental conductance method, an advanced incremental conductance control algorithm was proposed, which can track maximum power point rapidly and accurately. The oscillation phenomenon, which exists near the maximum power point, was improved at a great extent, so to the efficiency of photovoltaic cells generation electricity. The inverter control system has an advantage in its high speed and flexibility by applying advanced control algorithm. And the source harmonic current is remarkably reduced. In addition, the power factor is enhanced and the power quality is improved. Finally, according to the principle of inverter control system and based on the analysis on the mathematical model of photovoltaic inverter, a simulation model of that is established based on MATLAB/SIMULINK.

Characteristics of Stable Rotating Stall Cells in an Axial Compressor

2017 ◽  
Author(s):  
Adam R. Hickman ◽  
Scott C. Morris
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Pressure Ratio ◽  
Pressure Sensors ◽  
Axial Compressor ◽  
Field Measurements ◽  
Rotating Stall ◽  
Flow Coefficient ◽  
Stable Operation ◽  
Double Phase

Flow field measurements of a high-speed axial compressor are presented during pre-stall and post-stall conditions. The paper provides an analysis of measurements from a circumferential array of unsteady shroud static pressure sensors during stall cell development. At low-speed, the stall cell approached a stable size in approximately two rotor revolutions. At higher speeds, the stall cell developed within a short amount of time after stall inception, but then fluctuated in circumferential extent as the compressor transiently approached a stable post-stall operating point. The size of the stall cell was found to be related to the annulus average flow coefficient. A discussion of Phase-Locked Average (PLA) statistics on flow field measurements during stable operation is also included. In conditions where rotating stall is present, flow field measurements can be Double Phase-Locked Averaged (DPLA) using a once-per-revolution (1/Rev) pulse and the period of the stall cell. The DPLA method provides greater detail and understanding into the structure of the stall cell. DPLA data indicated that a stalled compressor annulus can be considered to contained three main regions: over-pressurized passages, stalled passages, and recovering passages. Within the over-pressured region, rotor passages exhibited increased blade loading and pressure ratio compared to pre-stall values.

The Effect of Transient Fuel Staging on Self-Excited Instabilities in a Multi-Nozzle Model Gas Turbine Combustor

2017 ◽  
Author(s):  
Wyatt Culler ◽  
Janith Samarasinghe ◽  
Bryan D. Quay ◽  
Domenic A. Santavicca ◽  
Jacqueline O’Connor
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
High Speed ◽  
Equivalence Ratio ◽  
Growth Time ◽  
Stable Operation ◽  
Time Constants ◽  
Decay Times ◽  
Fuel Staging ◽  
Passive Techniques

Combustion instability in gas turbines can be mitigated using active techniques or passive techniques, but passive techniques are almost exclusively used in industrial settings. While fuel staging, a common passive technique, is effective in reducing the amplitude of self-excited instabilities in gas turbine combustors at steady-state conditions, the effect of transients in fuel staging on self-excited instabilities is not well understood. This paper examines the effect of fuel staging transients on a laboratory-scale five-nozzle can combustor undergoing self-excited instabilities. The five nozzles are arranged in a four-around-one configuration and fuel staging is accomplished by increasing the center nozzle equivalence ratio. When the global equivalence ratio is φ = 0.70 and all nozzles are fueled equally, the combustor undergoes self-excited oscillations. These oscillations are suppressed when the center nozzle equivalence ratio is increased to φ = 0.80 or φ = 0.85. Two transient staging schedules are used, resulting in transitions from unstable to stable operation, and vice-versa. It is found that the characteristic instability decay times are dependent on the amount of fuel staging in the center nozzle. It is also found that the decay time constants differ from the growth time constants, indicating hysteresis in stability transition points. High speed CH* chemiluminescence images in combination with dynamic pressure measurements are used to determine the instantaneous phase difference between the heat release rate fluctuation and the combustor pressure fluctuation throughout the combustor. This analysis shows that the instability onset process is different from the instability decay process.

scholarly journals Numerical study of unsteady flow and exciting force for swept turbomachinery blades

2016 ◽  
Vol 20 (suppl. 3) ◽  
pp. 669-676
Author(s):  
Di Zhang ◽  
Ma Jiao-Bin ◽  
Qi Jing
Keyword(s):  
Boundary Layer ◽  
Unsteady Flow ◽  
Pressure Fluctuation ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Aerodynamic Performance ◽  
Rotor Blades ◽  
Stable Operation ◽  
Straight Blade ◽  
Excitation Force

The aerodynamic performance of blade affects the vibration characteristics and stable operation of turbomachinery closely. The aerodynamic performance of turbine stage can be improved by using swept blade. In this paper, the RANS method and the RNG k-? turbulence mode were adopted to investigate the unsteady flow characteristics and excitation force of swept blade stage. According to the results, for the swept blade, the fluid of boundary layer shifts in radial direction due to the influence of geometric construction. It is observed that there is similar wake development for several kinds of stators, and the wake has a notable effect on the boundary layer of the rotor blades. When compared with straight blade, pressure fluctuation of forward-swept blade is decreased while the pressure fluctuation of backward-swept blade is increased. The axial and tangential fundamental frequency excitation force factors of 15?forward-swept blade are 0.139 and 0.052 respectively, which are the least, and all excitation force factors are in the normal range. The excitation factor of the forward-swept blade is decreased compared with straight blade, and the decreasing percentage is closely related to the swept angle. As for backward-swept blades, the situation is the other way around. Additionally, the change of axial excitation factor is more obvious. So the vibration reduction performance of forward-swept blade is better.

scholarly journals METHOD OF SELECTING THE OPERATION PARAMETERS OF ELECTRIC SPINDLE WITH AEROSTATIC SUPPORTS FOR SEPARATION OF SEMICONDUCTOR PLATES TO CRYSTALS. PARTS 2–3

2021 ◽  
Vol 3 (56) ◽  
pp. 25-41
Author(s):  
Alexander E. KOVENSKY ◽  
◽  
Vladimir L. BASINIUK ◽  
Ryta E. VOLKOTRUB ◽  
◽  
...  
Keyword(s):  
Rotational Speed ◽  
High Speed ◽  
Resonant Mode ◽  
Forced Oscillations ◽  
Diamond Cutting ◽  
Spindle Shaft ◽  
Operation Parameters ◽  
Main Components ◽  
Full Scale Tests ◽  
Diamond Disc

The article presents the results of studies of the shaft oscillation processes of a precision horizontal highspeed electric spindle with aerostatic radial and axial supports, used at Planar OJSC in equipment for separation of semiconductor plates into crystals. The studies were carried out using the developed mathematical models that take into account the design features of these electric spindles, including the cantilever mounting of the cutting tool, the imbalance of the diamond disc with the mandrel and the mass ratio of the main components of the electric spindle, as well as the results of their full-scale tests. Based on the analysis of the data obtained, regularities are shown that connect the amplitude values of the oscillations of the electric spindle shaft with the imbalance of the diamond disc with the mandrel and the rotational speed of the electric spindle, which made it possible to propose engineering dependences for choosing the permissible values of the imbalance and rational, from the standpoint of resonance conditions and permissible shaft oscillations, rotational speed of the electric spindle. Recommendations have been developed for the creation of a system for monitoring and active control of the parameters and functioning of the electric spindle in the process of separating semiconductor plates into crystals, which make it possible to use the resonant mode of radial oscillations to improve cutting conditions, excluding direct contact of the working surfaces of aerostatic supports, their seizure and loss of performance of the electric spindle. The article presents a method of selecting the operation parameters of a high-speed precision horizontal electric spindle with aerostatic radial and axial supports and a cantilever mounting of a diamond cutting disc. It is based on the analysis of the simulation results of shaft forced oscillations and data on the shaft oscillations during the operation of the electric spindle with different rotation frequencies and imbalances. The results obtained can be used to monitor shaft oscillations during the operation of the electric spindle, while the high operation efficiency of which is achieved by adaptive control of rotation frequencies taking into account the amplitudes of these oscillations.

Application of R/S Rheometer in Low Temperature Drilling Fluid Rheology Determination

2012 ◽  
Vol 490-495 ◽  
pp. 3114-3118
Author(s):  
Xiao Ling Jiang ◽  
Zong Ming Lei ◽  
Kai Wei
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Low Temperature ◽  
High Speed ◽  
Drilling Fluid ◽  
Drilling Fluids ◽  
Rheological Parameter ◽  
Fluid Temperature ◽  
Fluid Rheology ◽  
Rotary Viscometer

With six-speed rotary viscometer measuring the rheology of drilling fluid at low temperature, during the high-speed process, the drilling fluid temperature is not constant at low temperature, which leads to the inaccuracy in rheological measurement. When R/S rheometer is used cooperating with constant low-temperature box , the temperature remains stable during the process of determining the drilling fluid rheology under low temperature. The R/S rheometer and the six-speed rotational viscometer are both coaxial rotational viscometers, but they work in different ways and the two cylindrical clearance between them are different.How to make two viscometer determination result can maintain consistent?The experimental results show that, The use of R/S rheometer, with the shear rate for 900s-1 shear stress values instead of six speed rotary viscometer shear rate for 1022s-1 shear stress values.Then use two-point formula to calculate rheological parameters.The R/S rheometer rheological parameter variation with temperature has a good linear relationship,Can better reflect the rheological properties of drilling fluids with low temperature changerule

On the performance of foil thrust bearing with misaligned bearing runner

2017 ◽  
Vol 69 (2) ◽  
pp. 105-115 ◽  
Author(s):  
Abdelrasoul M. Gad
Keyword(s):  
High Speed ◽  
Thrust Bearing ◽  
Approximation Technique ◽  
Hydrodynamic Effect ◽  
Stable Operation ◽  
Content Type ◽  
Thrust Bearings ◽  
Load Carrying ◽  
Foil Thrust Bearing ◽  
Stiffness And Damping

Purpose Compliant foil thrust bearings are promising bearings for high-speed oil-free turbomachinery. However, most previous experimental and numerical approaches to investigate the performance of these bearings have ignored the effect of bearing runner misalignment. Therefore, this paper aims to evaluate the effects of static and dynamic angular misalignments of the bearing runner on the performance of a gas-lubricated foil thrust bearing. Design/methodology/approach The bearing runner is allowed a maximum angular misalignment that produces a minimum gas film thickness as low as 20 per cent of the nominal clearance. Then, the variations of bearing load carrying capacity, viscous power loss and stiffness and damping coefficients of the gas film with runner misalignment are thoroughly analyzed. The flow in the gas film is modeled with compressible Reynolds equation along with the Couette approximation technique, and the deformation of the compliant bearing is calculated with a robust analytical model. Small perturbations method is used to calculate the force and moment dynamic coefficients of the gas film. Findings The results show that misaligned foil thrust bearings are capable of developing a restoring moment sufficient enough to withstand the imposed misalignments. Furthermore, the enhanced hydrodynamic effect ensures a stable operation of the misaligned bearing, and the results highlighted the role of the compliant bearing structure to maintain foil bearing prominent features even at misaligned conditions. Originality/value The value of this study is the evaluation of the effects of runner angular misalignments on the static and dynamic characteristics of Generation II bump-type foil thrust bearing.

ASSESSMENT OF MULTALL AS CFD CODE FOR THE ANALYSIS OF TUBE-AXIAL FANS

2021 ◽  
pp. 1-12
Author(s):  
Piero Danieli ◽  
Massimo Masi ◽  
Giovanni Delibra ◽  
Alessandro Corsini ◽  
Andrea Lazzaretto
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Velocity Distribution ◽  
High Speed ◽  
State Of The Art ◽  
Stable Operation ◽  
Pressure Curve ◽  
Analysis Tool ◽  
Low Speed ◽  
Axial Fans

Abstract This work deals with the application of the open source CFD code MULTALL to the analysis of tube-axial-fans. The code has been widely validated in the literature for high-speed turbomachine flows but not applied yet to low speed tutbomachines. The aim of this work is to assess the degree of reliability of MULTALL as a tool for simulating the internal flow in industrial axial-flow fan rotors. To this end, the predictions of the steady-state air flow field in the annular sector of a 315 mm tube-axial fan obtained by MULTALL 18.3 are compared with those obtained by two state-of-the-art CFD codes and experimental data of the global aerodynamic performance of the fan and the pitch-wise averaged velocity distribution downstream of the rotor. All the steady-state RANS calculations were performed on either fully structured hexahedron or hexa-dominant grids using classical formulations of algebraic turbulence models. The pressure curve and the trend of the aeraulic efficiency in the stable operation range of the fan predicted by MULTALL show very good agreement with both the experimental data and the other CFD results. Although the estimation of the fan efficiency predicted by MULTALL can be noticeably improved by the more sophisticated state-of-the-art CFD codes, the analysis of the velocity distribution at the rotor exit supports the use of MULTALL as a reliable CFD analysis tool for designers of low-speed axial fans.

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