To see the other types of publications on this topic, follow the link: Axial thrust force of a turbine.
Journal articles on the topic 'Axial thrust force of a turbine'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Axial thrust force of a turbine.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Zhang, Fei, Yue Lv, Zhonghua Gui, and Zhengwei Wang. "Effect of the Diameter of Pressure-Balance Pipe on Axial Hydraulic Thrust." Journal of Marine Science and Engineering 9, no. 7 (June 30, 2021): 724. http://dx.doi.org/10.3390/jmse9070724.
Full textAbstract:
The axial hydraulic thrust has great influence on the safety and stability of a pump turbine. A common way to balance hydraulic thrust is to install a pressure-balance pipe, and the change in pipe diameter is one of the important factors affecting axial hydraulic thrust. In this paper, the influence of the diameter changes in a pressure-balance pipe on axial hydraulic thrust of a pump turbine, plus the seal clearance flow, is studied and analyzed under three work conditions, i.e., 100%, 75%, and 50% loads. It is found that under 100% and 75% load conditions, the axial hydraulic thrust increases vertically with the increase in pipe diameter; whereas, under 50% load condition, the axial hydraulic thrust increases first and then decreases with the increase in pipe diameter. The results aim to give guidelines for the choice of pressure-balance pipe diameters and to control the axial hydraulic thrust of a pumped-storage power station, so that the hydraulic excitation force can be better matched with the hydraulic mechanism.
2
Revaz, Tristan, and Fernando Porté-Agel. "Large-Eddy Simulation of Wind Turbine Flows: A New Evaluation of Actuator Disk Models." Energies 14, no. 13 (June 22, 2021): 3745. http://dx.doi.org/10.3390/en14133745.
Full textAbstract:
Large-eddy simulation (LES) with actuator models has become the state-of-the-art numerical tool to study the complex interaction between the atmospheric boundary layer (ABL) and wind turbines. In this paper, a new evaluation of actuator disk models (ADMs) for LES of wind turbine flows is presented. Several details of the implementation of such models are evaluated based on a test case studied experimentally. In contrast to other test cases used in previous similar studies, the present test case consists of a wind turbine immersed in a realistic turbulent boundary-layer flow, for which accurate data for the turbine, the flow, the thrust and the power are available. It is found that the projection of the forces generated by the turbine into the flow solver grid is crucial for rotor predictions, especially for the power, and less important for the wake flow prediction. In this context, the projection of the forces into the flow solver grid should be as accurate as possible, in order to conserve the consistency between the computed axial velocity and the projected axial force. Also, the projection of the force is found to be much more important in the rotor plane directions than in the streamwise direction. It is found that for the case of a wind turbine immersed in a realistic turbulent boundary-layer flow, the potential spurious numerical oscillations originating from sharp force projections are not harmful to the results. By comparing an advanced model which computes the non-uniform distribution of the turbine forces over the rotor with a simple model which assumes uniform effects of the turbine forces, it is found that both can lead to accurate results for the far wake flow and the thrust and power predictions. However, the comparison shows that the advanced model leads to better results for the near wake flow. In addition, it is found that the simple model overestimates the rotor velocity prediction in comparison to the advanced model. These elements are explained by the lack of local feedback between the axial velocity and the axial force in the simple model. By comparing simulations with and without including the effects of the nacelle and tower, it is found that the consideration of the nacelle and tower is relatively important both for the near wake and the power prediction, due to the shadow effects. The grid resolution is not found to be critical once a reasonable resolution is used, i.e. in the order of 10 grid points along each direction across the rotor. The comparison with the experimental data shows that an accurate prediction of the flow, thrust, and power is possible with a very reasonable computational cost. Overall, the results give important guidelines for the implementation of ADMs for LES.
3
Qiu, Li Jun, Jia Yang, and Su Ying Xu. "The Analysis and Design of Turbocharger Thrust Bearing." Advanced Materials Research 308-310 (August 2011): 1333–36. http://dx.doi.org/10.4028/www.scientific.net/amr.308-310.1333.
Full textAbstract:
Turbocharger turbine shaft thrust bearing is the role of high-speed rotating turbine to withstand the axial force generated by the turbine shaft and a part of the axial position. Fixed on the intermediate thrust bearing on the two sides and both sides of the ring, respectively, relative sliding. Sliding contact surface produces a condition of dynamic pressure oil film structure and shape of the oil wedge. Bearing the sides of the structural design of the oil wedge slot and forming a design to solve the main content. Bearing thrust bearing stiffness and rotation in the process of stress state and the smooth line is to improve the bearing life. Rotating turbine shaft to ensure the accuracy of key factors. Method of lubricating oil to the oil and oil Xie in the shape and precision bearings to ensure the prerequisite conditions and service life.
4
Lee, In-Beom, Seong-Ki Hong, and Bok-Lok Choi. "Investigation of the axial thrust load using numerical and experimental techniques during turbocharger operation." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 232, no. 6 (May 25, 2017): 755–65. http://dx.doi.org/10.1177/0954407017706859.
Full textAbstract:
Identification of the axial thrust load during the operating conditions of a turbocharger provides useful information to turbocharger designers. The axial force acting on the thrust bearing is mainly caused by the imbalance between the turbine wheel and the compressor wheel. It has a significant influence on the friction losses, which reduce the efficiency and the performance of a high-speed turbocharger. Well-known formulae for calculating the thrust load and the mechanical friction have been given in the literature. However, it is difficult to determine an accurate axial force by an analytical approach. This paper presents a detailed procedure for prediction of the axial thrust load during turbocharger operation. The first step is to identify the relationship between the externally applied load and the strain response using a specially designed test device and a numerical method. Next, if the operating strains and temperatures are measured, the strain signals due to the axial thrust can be adjusted by subtracting the thermal effects from the measured strains. Finally, the thrust loads in particular operating conditions are inversely obtained by inserting the adjusted strains into the calibration equations.
5
Sun, Huifang, Yue Lv, Jinbing Ni, Xianyu Jiang, and Zhengwei Wang. "Effect of Seal Locations of Pump-Turbine on Axial Hydraulic Trust." Journal of Marine Science and Engineering 9, no. 6 (June 4, 2021): 623. http://dx.doi.org/10.3390/jmse9060623.
Full textAbstract:
Axial hydraulic thrust is an important factor that affects safety and stability of pump turbine operation. Research and analysis of axial hydraulic thrust is of a great significance for guiding the safe and stable operation of a pumped storage power station. Since the runner shape of the pump turbine is flat and its radial dimension is large, an increase of leakage can happen easily. In order to reduce the leakage and improve the efficiency of the unit, a labyrinth ring seal is usually used in the upper crown and lower ring of the runner because the inner clearance of the seal has a great influence on the axial thrust. In order to study the influence of the change of labyrinth seal position on axial hydraulic thrust, a fluid domain model with a pressure balance pipe, upper crown clearance, and lower ring clearance is established for a pump turbine of a power station. The distribution position of labyrinth ring in the upper crown clearance is changed. The CFD numerical simulations are carried out under both 100% working load and 75% working load of turbine conditions, considering the flow in clearance areas. The research results of this paper have found that the axial hydraulic thrust of the 100% load condition is consistent with the change of the gap position compared with the 75% load condition. The amplitude of the change of the water thrust under the 100% load condition is greater. As the sealing position of the labyrinth ring in the upper crown gap moves away from the central axis, the resultant vertical and upward water thrust increases, and the operating efficiency of the unit first increases and then decreases. As the position of the labyrinth ring seal in the upper ring clearance moves away from the central axis, the resultant vertical and upward water thrust increases, and the operating efficiency of the unit first increases and then decreases. Defining the radial dimension ratio δ between the front clearance area and the total area of labyrinth ring, the closer δ is to 0.5, the unit efficiency is higher; the smaller that δ is, then the high pressure area in the upper crown clearance is smaller, and the hydraulic thrust force increases vertically. Considering a variety of factors, the clearance seal position has the optimal value. In the practical application of the project, the condition of excessive upward hydraulic thrust leading to the lifting of the unit can be avoided, and the phenomenon of excessive downward hydraulic thrust leading to the excessive load-bearing of the frame is evitable.
6
Mao, Zhongyu, Ran Tao, Funan Chen, Huili Bi, Jingwei Cao, Yongyao Luo, Honggang Fan, and Zhengwei Wang. "Investigation of the Starting-Up Axial Hydraulic Force and Structure Characteristics of Pump Turbine in Pump Mode." Journal of Marine Science and Engineering 9, no. 2 (February 5, 2021): 158. http://dx.doi.org/10.3390/jmse9020158.
Full textAbstract:
During the starting up of the pump mode in pump turbines, the axial hydraulic force acting on the runner would develop with the guide vane opening. It causes deformation and stress on the support bracket, main shaft and runner, which influence the operation security. In this case, the axial hydraulic force of the pump turbine is studied during the starting up of pump mode. Its influences on the support bracket and main shaft are investigated in detail. Based on the prediction results of axial hydraulic force, the starting-up process can be divided into “unsteady region” and “Q flat region” with obviously different features. The mechanism is also discussed by analyzing pressure distributions and streamlines. The deformation of the support bracket and main shaft are found to have a relationship with the resultant force on the crown and band. A deflection is found on the deformation of the runner with the nodal diameter as the midline in the later stages of the starting-up process. The reason is discussed according to pressure distributions. The stress concentration of the support bracket is found on the connection between thrust seating and support plates. The stress of the runner is mainly on the connection between the crown and the blade’s leading-edge. This work will provide more useful information and strong references for similar cases. It will also help in the design of pump turbine units with more stabilized systems for reducing over-loaded hydraulic force, and in the solving of problems related to structural characteristics.
7
Cho, Soo-Yong, Yang-Beom Jung, and Kwang Phil Kyun. "Axial Force Prediction and Maneuvering on the Thrust Bearing on a Two-Stage Radial Turbine." Journal of the Korean Society for Power System Engineering 22, no. 5 (October 31, 2018): 51–62. http://dx.doi.org/10.9726/kspse.2018.22.5.051.
Full text
8
Wimshurst, A., and R. Willden. "Spanwise flow corrections for tidal turbines." International Marine Energy Journal 1, no. 2 (Nov) (November 1, 2018): 111–21. http://dx.doi.org/10.36688/imej.1.111-121.
Full textAbstract:
Actuator line computations of two different tidal turbine rotor designs are presented over a range of tip speed ratios. To account for the reduction in blade loading on the outboard sections of these rotor designs, a spanwise flow correction is applied. This spanwise flow correction is a modified version of the correction factor of Shen et al. (Wind Energy 2005; 8: 457-475) which was originally developed for wind turbine rotors at high tip speed ratios. The modified correction is described as ‘directionally dependent’ in that it allows a more aggressive reduction in the tangential (torque producing) direction than the axial (thrust producing) direction and hence allows the sectional force vector to rotate away from the rotor plane (towards the streamwise direction). When using the modified correction factor, the actuator line computations show a significant improvement in the accuracy of prediction of the rotor thrust and torque, when compared to similar actuator line computations that do not allow the sectional force vector to rotate. Furthermore, the rotation of the sectional force vector is attributed to the changing surface pressure distribution on the outboard sections of the blade, which arises from the spanwise flow along the blade. The rotation of the sectional force vector can also be used to explain the reduction in sectional lift coefficient and increase in sectional drag coefficient that has been observed on the outboard blade sections of several rotors in the literature
9
Tongchitpakdee, Chanin, Sarun Benjanirat, and Lakshmi N. Sankar. "Numerical Studies of the Effects of Active and Passive Circulation Enhancement Concepts on Wind Turbine Performance." Journal of Solar Energy Engineering 128, no. 4 (July 16, 2006): 432–44. http://dx.doi.org/10.1115/1.2346704.
Full textAbstract:
The aerodynamic performance of a wind turbine rotor equipped with circulation enhancement technology (trailing-edge blowing or Gurney flaps) is investigated using a three-dimensional unsteady viscous flow analysis. The National Renewable Energy Laboratory Phase VI horizontal axis wind turbine is chosen as the baseline configuration. Experimental data for the baseline case is used to validate the flow solver, prior to its use in exploring these concepts. Calculations have been performed for axial and yawed flow at several wind conditions. Results presented include radial distribution of the normal and tangential forces, shaft torque, root flap moment, and surface pressure distributions at selected radial locations. At low wind speed (7m∕s) where the flow is fully attached, it is shown that a Coanda jet at the trailing edge of the rotor blade is effective at increasing circulation resulting in an increase of lift and the chordwise thrust force. This leads to an increased amount of net power generation compared to the baseline configuration for moderate blowing coefficients (Cμ⩽0.075). A passive Gurney flap was found to increase the bound circulation and produce increased power in a manner similar to Coanda jet. At high wind speed (15m∕s) where the flow is separated, both the Coanda jet and Gurney flap become ineffective. The effects of these two concepts on the root bending moments have also been studied.
10
Chen, Huixiang, Daqing Zhou, Yuan Zheng, Shengwen Jiang, An Yu, and You Guo. "Load Rejection Transient Process Simulation of a Kaplan Turbine Model by Co-Adjusting Guide Vanes and Runner Blades." Energies 11, no. 12 (November 30, 2018): 3354. http://dx.doi.org/10.3390/en11123354.
Full textAbstract:
To obtain the flow mechanism of the transient characteristics of a Kaplan turbine, a three-dimensional (3-D) unsteady, incompressible flow simulation during load rejection was conducted using a computational fluid dynamics (CFD) method in this paper. The dynamic mesh and re-meshing methods were performed to simulate the closing process of the guide vanes and runner blades. The evolution of inner flow patterns and varying regularities of some parameters, such as the runner rotation speed, unit flow rate, unit torque, axial force, and static pressure of the monitored points were revealed, and the results were consistent with the experimental data. During the load rejection process, the guide vane closing behavior played a decisive role in changing the external characteristics and inner flow configurations. In this paper, the runner blades underwent a linear needle closure law and guide vanes operated according to a stage-closing law of “first fast, then slow,” where the inflection point was t = 2.3 s. At the segment point of the guide vane closing curve, a water hammer occurs between guide vanes and a large quantity of vortices emerged in the runner and the draft tube. The pressure at the measurement points changes dramatically and the axial thrust rises sharply, marking a unique time in the transient process. Thus, the quality of a transient process could be effectively improved by properly setting the location of segmented point. This study conducted a dynamic simulation of co-adjustment of the guide vanes and the blades, and the results could be used in fault diagnosis of transient operations at hydropower plants.
11
Alber, Jörg, Rodrigo Soto-Valle, Marinos Manolesos, Sirko Bartholomay, Christian Navid Nayeri, Marvin Schönlau, Christian Menzel, Christian Oliver Paschereit, Joachim Twele, and Jens Fortmann. "Aerodynamic effects of Gurney flaps on the rotor blades of a research wind turbine." Wind Energy Science 5, no. 4 (November 26, 2020): 1645–62. http://dx.doi.org/10.5194/wes-5-1645-2020.
Full textAbstract:
Abstract. This paper investigates the aerodynamic impact of Gurney flaps on a research wind turbine of the Hermann-Föttinger Institute at the Technische Universität Berlin. The rotor radius is 1.5 m, and the blade configurations consist of the clean and the tripped baseline cases, emulating the effects of forced leading-edge transition. The wind tunnel experiments include three operation points based on tip speed ratios of 3.0, 4.3, and 5.6, reaching Reynolds numbers of approximately 2.5×105. The measurements are taken by means of three different methods: ultrasonic anemometry in the wake, surface pressure taps in the midspan blade region, and strain gauges at the blade root. The retrofit applications consist of two Gurney flap heights of 0.5 % and 1.0 % in relation to the chord length, which are implemented perpendicular to the pressure side at the trailing edge. As a result, the Gurney flap configurations lead to performance improvements in terms of the axial wake velocities, the angles of attack and the lift coefficients. The enhancement of the root bending moments implies an increase in both the rotor torque and the thrust. Furthermore, the aerodynamic impact appears to be more pronounced in the tripped case compared to the clean case. Gurney flaps are considered a passive flow-control device worth investigating for the use on horizontal-axis wind turbines.
12
Ehrich, Sebastian, Carl Schwarz, Hamid Rahimi, Bernhard Stoevesandt, and Joachim Peinke. "Comparison of the Blade Element Momentum Theory with Computational Fluid Dynamics for Wind Turbine Simulations in Turbulent Inflow." Applied Sciences 8, no. 12 (December 6, 2018): 2513. http://dx.doi.org/10.3390/app8122513.
Full textAbstract:
In this work three different numerical methods are used to simulate a multi-megawatt class class wind turbine under turbulent inflow conditions. These methods are a blade resolved Computational Fluid Dynamics (CFD) simulation, an actuator line based CFD simulation and a Blade Element Momentum (BEM) approach with wind fields extracted from an empty CFD domain. For all three methods sectional and integral forces are investigated in terms of mean, standard deviation, power spectral density and fatigue loads. It is shown that the average axial and tangential forces are very similar in the mid span, but differ a lot near the root and tip, which is connected with smaller values for thrust and torque. The standard deviations in the sectional forces due to the turbulent wind fields are much higher almost everywhere for BEM than for the other two methods which leads to higher standard deviations in integral forces. The difference in the power spectral densities of sectional forces of all three methods depends highly on the radial position. However, the integral densities are in good agreement in the low frequency range for all methods. It is shown that the differences in the standard deviation between BEM and the CFD methods mainly stem from this part of the spectrum. Strong deviations are observed from 1.5 Hz onward. The fatigue loads of torque for the CFD based methods differ by only 0.4%, but BEM leads to a difference of up to 16%. For the thrust the BEM simulation results deviate by even 29% and the actuator line by 7% from the blade resolved case. An indication for a linear relation between standard deviation and fatigue loads for sectional as well as integral quantities is found.
13
Agbormbai, James, Weidong Zhu, and Liang Li. "Vortex Ring Theory—An Alternative to the Existing Actuator Disk and Rotating Annular Stream Tube Theories." Applied Sciences 11, no. 14 (July 17, 2021): 6576. http://dx.doi.org/10.3390/app11146576.
Full textAbstract:
Currently, the actuator disk theory (ADT) and the rotating annular stream-tube theory (RAST), both of which predicate on the axial momentum and generalized momentum theories, among others, are commonly used in investigating the aerodynamic characteristics of horizontal axis wind turbines (HAWTs). These theories, which are based on a rotor with an infinite number of blades, typically do not properly capture the flow physics of wind blowing past the rotors of HAWTs. A vortex ring theory (VRT) that analyzes HAWTs based solely on the characteristics of fluids flowing past obstructions is proposed. The VRT is not predicated on the assertion that the induced velocity in the wake is twice the induced velocity at the rotor. On the contrary, it splits the axial induction factor in the wake into two components, namely, the induction or interference factor due to the solidity of the rotor and the induction factor due to the wake of the rotor aw; aw and its azimuthal counterpart are determined using the Biot–Savart law. The pressure differences across the rotor segments of a HAWT are derived from the Bernoulli equation for all the three theories. Blade segment/local areas based on the blade sectional geometry of the rotor are used in the case of the VRT to estimate the local forces. All the calculations in this study are based on the design parameters of the 5MW National Renewable Energy Laboratory’s reference offshore wind turbine. Pressure differences are plotted as functions of local radii using the calculated axial and azimuthal induction factors for each theory. The local power coefficient is plotted as a function of the local tip-speed ratio, while the local thrust coefficient is plotted as a function of the local radii for all the three theories. There is piece-wise agreement between the VRT, the ADT, the RAST and numerical and experimental data available in the literature.
14
Tiainen, Jonna, Ahti Jaatinen-Värri, Aki Grönman, Petri Sallinen, Juha Honkatukia, and Toni Hartikainen. "Validation of the Axial Thrust Estimation Method for Radial Turbomachines." International Journal of Rotating Machinery 2021 (February 24, 2021): 1–18. http://dx.doi.org/10.1155/2021/6669193.
Full textAbstract:
The fast preliminary design and safe operation of turbomachines require a simple and accurate prediction of axial thrust. An underestimation of these forces may result in undersized bearings that can easily overload and suffer damage. While large safety margins are used in bearing design to avoid overloading, this leads to costly oversizing. In this study, the accuracy of currently available axial thrust estimation methods is analyzed by comparing them to each other and to theoretical pressure distribution, numerical simulations, and new experimental data. Available methods tend to underestimate the maximum axial thrust and require data that are unavailable during the preliminary design of turbomachines. This paper presents a new, simple axial thrust estimation method that requires only a few preliminary design parameters as the input data and combines the advantages of previously published methods, resulting in a more accurate axial thrust estimation. The method is validated against previously public data from a radial pump and new experimental data from a centrifugal compressor, the latter measured at Lappeenranta-Lahti University of Technology LUT, Finland, and two gas turbines measured at Aurelia Turbines Oy, Finland. The maximum deviation between the estimated axial thrust using the hybrid method and the measured one is less than 13%, while the other methods deviate by tens of percent.
15
Xia, Bin, Fanyu Kong, Hui Zhang, Lei Yang, and Wanghuan Qian. "Investigation of axial thrust deviation between the theory and experiment for high-speed mine submersible pump." Advances in Mechanical Engineering 10, no. 8 (August 2018): 168781401878925. http://dx.doi.org/10.1177/1687814018789256.
Full textAbstract:
In this article, three types of high-speed mine submersible pumps were designed and experimented. During the reliability performance test, the axial thrust balancing device of GFQ150-700 was overloaded and damaged due to an unsuitable designed value of axial thrust. The designed hydraulic axial thrust with the actual value is compared in this article, and the reason for axial thrust deviation is discussed. Results show that axial thrust of the theoretical calculation is close to the numerical simulation value at a certain extent. GFQ100-1000 obtains the maximum theoretical axial thrust, while the maximum simulated value is produced in GFQ150-700, and that is corroborated by experiments. The axial blade force is related to the pump stage and area differences between the blade suction and pressure surface. Due to the increasing stage in GFQ100-1000, the axial blade force increases to a remarkable value in an opposite direction with respect to GFQ150-700. The opposite blade force offsetting other hydraulic forces in GFQ100-1000 is responsible for the maximum hydraulic axial thrust emerges in GFQ150-700 instead of GFQ100-1000.
16
Ji, Xing-Ying, Xiao-Bin Li, Wen-Tao Su, Xu Lai, and Tian-Xiao Zhao. "On the hydraulic axial thrust of Francis hydro-turbine." Journal of Mechanical Science and Technology 30, no. 5 (May 2016): 2029–35. http://dx.doi.org/10.1007/s12206-016-0409-x.
Full text
17
Leksono, S., I. Ketut Aria Pria Utama, and Wasis Dwi Aryawan. "Minimizing Axial Energy Loss by Using Vane Turbine in the Propeller Slipstream." Applied Mechanics and Materials 664 (October 2014): 138–42. http://dx.doi.org/10.4028/www.scientific.net/amm.664.138.
Full textAbstract:
The paper describes the results of analytical investigation on the application of vane-turbine in the propeller slipstream. The vane-turbine is attached on single-and twin-screw ships with total number of investigated ships are 20. Performance of the turbine was analyzed by actuator disc method. The effect of vane-turbine on ship performance is investigated. Discussions are focused on two main topics, namely speed loss and power efficiency gain. Final result finds out that the ratio of the thrust-power producing by vane turbine and thrust-power producing by propeller will influence the efficiency gain.
18
Chen, Xue Mei, Qing Liang Chen, Feng Tao He, and Xi Feng Fan. "Experimental Study on Orbital Drilling Force and Machining Quality of CFRP." Advanced Materials Research 1061-1062 (December 2014): 542–49. http://dx.doi.org/10.4028/www.scientific.net/amr.1061-1062.542.
Full textAbstract:
This paper aims to investigate orbital drilling process in carbon-fiber reinforced plastic (CFRP) composites with multi-point orbital drilling tool based on the robot automatic drilling system. One orthogonal experiment has been carried out, and the cutting forces of different parameters were measured online by dynamometer. Furthermore, the cutting force model was established through regression analysis, and the impacts of cutting parameters on thrust force were deeply analyzed. In addition, delamination and tear defects were inspected respectively, and the relationship between thrust force and delamination and tear was discussed. Our results indicate that thrust force increased with the increasing feed rate and axial feed depth, while decreased with the increasing spindle speed. Axial feed depth was found as the predominant factor on thrust force and defects. At last, the cutting parameters was optimized and then thrust force decreased more than 26% with almost none tear and burr around the hole, which indicates a better machine quality.
19
Leto, Angelo. "Investigation of a Radial Turbines Compatibility for Small Rocket Engine." E3S Web of Conferences 197 (2020): 11009. http://dx.doi.org/10.1051/e3sconf/202019711009.
Full textAbstract:
In the radial turbine preliminary design for an expander rocket engine, a comparison was made with axial turbine used in Pratt & Whitney RL10 engine. One of the primary requirements of a liquid propellant rocket engine is the generation of a high thrust, which depends on both the mass flow rate of the propellant and the pressure in the thrust chamber. In expander-cycle engines, which are the subject of the present study, the liquid propellant is first compressed using centrifugal turbo-pumps, then it is used to cool the combustion chamber and the nozzle and, once vaporized, it flows through the turbines used to drive the turbo-pumps. The aim was to demonstrate the greater efficiency of the radial turbine with a reduction of the pressure ratio with respect to the axial turbine.
20
Baun, D. O., and R. D. Flack. "A Plexiglas Research Pump With Calibrated Magnetic Bearings/Load Cells for Radial and Axial Hydraulic Force Measurement." Journal of Fluids Engineering 121, no. 1 (March 1, 1999): 126–32. http://dx.doi.org/10.1115/1.2821992.
Full textAbstract:
A research pump intended for both flow visualization studies and direct measurement of hydrodynamic radial and axial forces has been developed. The impeller and the volute casing are constructed from Plexiglas which facilitates optical access for laser velocimetry measurements of the flow field both inside the impeller and in the volute casing. The pump housing is designed for flexibility allowing for each interchange of impellers and volute configurations. The pump rotor is supported by three radial magnetic bearings and one double acting magnetic thrust bearing. The magnetic bearings have been calibrated to characterize the force versus coil current and air gap relationship for each bearing type. Linear calibration functions valid for rotor eccentricities of up to 2/3 of the nominal bearing clearances and force level of ±58 N (13 lbf) and ±267 N (60 lbf) for the radial and axial bearings, respectively, were found. A detailed uncertainty analysis of the force calibration functions was conducted such that meaningful uncertainty bounds can be applied to in situ force measurements. Hysteresis and eddy current effects were quantified for each bearing such that their effect on the in situ force measurements could be assessed. By directly measuring the bearing reaction forces it is possible to determine the radial and axial hydraulic loads acting on the pump impeller. To demonstrate the capability of the magnetic bearings as active load cells representative hydraulic force measurements for a centered 4 vane 16 degree log spiral radial flow impeller operating in a single tongue spiral volute casing were made. At shut-off a nondimensional radial thrust of 0.084 was measured. A minimum nondimensional radial thrust of about 0.007 was observed at the nominal design flow. The nondimensional radial thrust increased to about 0.019 at 120 percent of design flow. The nondimensional axial thrust had a maximum at shut-off of 0.265 and decreased steadily to approximately 0.185 at 120 percent of design flow. Two regions of increasing axial thrust, in the flow range 75 to 100 percent of design flow, were observed. The measurements are compared to radial and axial force predictions using classical force models. The direct radial force measurements are compared to a representative set of radial force measurements from the literature. In addition, the directly measured radial force at design flow is compared to a single representative radial force measurement (obtained from the literature) calculated from the combination of static pressure and net momentum flux distribution at the impeller exit.
21
KUROKAWA, Junichi, Morihito INAGAKI, Hiroshi IMAMURA, Tadashi TAGUCHI, Kazuo NIIKURA, and Jun MATSUI. "Transient Axial Thrust of High-Head Pump-Turbine at Load Rejection." Proceedings of the JSME annual meeting 2002.3 (2002): 181–82. http://dx.doi.org/10.1299/jsmemecjo.2002.3.0_181.
Full text
22
Hu, Bo, Xuesong Li, Yanxia Fu, Chunwei Gu, Xiaodong Ren, and Jiaxing Lu. "Axial Thrust, Disk Frictional Losses, and Heat Transfer in a Gas Turbine Disk Cavity." Energies 12, no. 15 (July 29, 2019): 2917. http://dx.doi.org/10.3390/en12152917.
Full textAbstract:
The gas turbine is a kind of high-power and high-performance energy machine. Currently, it is a hot issue to improve the efficiency of the gas turbines by reducing the amount of secondary air used in the disk cavity. The precondition is to understand the effects of the through-flow rate on the axial thrust, the disk frictional losses, and the characteristics of heat transfer under various experimental conditions. In this paper, experiments are conducted to analyze the characteristics of flow and heat transfer. To ensure the safe operation of the gas turbine, the pressure distribution and the axial thrust are measured for various experimental conditions. The axial thrust coefficient is found to decrease as the rotational speed and the through-flow rate increases. By torque measurements, the amounts of the moment coefficient drop as the rotational speed increases while increase with through-flow rate. In order to better analyze the temperature field within the cavity, both the local and the average Nusselt number are investigated with the help of thermochromic liquid crystal technique. Four correlations for the local Nusselt number are determined according to the amounts of a through-flow coefficient. The results in this study can help the designers to better design the secondary air system in a gas turbine.
23
Wang, Yu Kui, Z. Q. Zeng, Zhen Long Wang, and Y. S. Huang. "Analysis of Elastic Deformation of Axial Foil Hydrodynamic Thrust Bearing Used in Turbine Generator." Advanced Materials Research 188 (March 2011): 199–202. http://dx.doi.org/10.4028/www.scientific.net/amr.188.199.
Full textAbstract:
In this paper, an elastic deformation of the axial foil hydrodynamic thrust bearing used in 100KW gas turbine generator is studied. The finite element model of the foil hydrodynamic thrust bearing was established using Solidworks and ANSYS. The foil hydrodynamic thrust bearing which considered foil deformation was analyzed and calculated based on the results of the approximate calculation. The FEA model considered the interaction of plane foil deformation and wave foil. The wave foil was not hypothesized as the linear distributed spring when set up the finite element model. The ANSYS results have demonstrated that the deformation of foil bearing designed based on the result of numerical calculation can meet the requirement of minimal film thickness of bearing lubricant layer.
24
Macháček, Michael, Stanislav Pospíšil, and Hrvoje Kozmar. "Scaling of wind turbine aerodynamics: wind tunnel experiments." MATEC Web of Conferences 313 (2020): 00053. http://dx.doi.org/10.1051/matecconf/202031300053.
Full textAbstract:
A small-scale wind turbine model was designed and manufactured to study its aerodynamic thrust force and the harvested flow energy. To provide a good understanding of the aerodynamics of the small-scale wind turbine at the low Reynolds number, the performance of three different types of blade airfoils was studied. The main motivation for the design of a new miniature wind turbine model was to achieve realistic values of the thrust force and the power coefficient on the model scale. A new blade profile with a thickness of 10% was designed and employed to reach the high tip-speed ratio, which is characteristic of contemporary wind turbines.
25
Dandekar, C., E. Orady, and P. K. Mallick. "Drilling Characteristics of an E-Glass Fabric-Reinforced Polypropylene Composite and an Aluminum Alloy: A Comparative Study." Journal of Manufacturing Science and Engineering 129, no. 6 (April 4, 2007): 1080–87. http://dx.doi.org/10.1115/1.2752827.
Full textAbstract:
This paper presents an experimental study on the drilling characteristics of an E-glass fabric-reinforced polypropylene composite and aluminum alloy 6061-T6. Both materials have many similar structural applications, especially in the automotive industry. The drilling characteristics considered were axial thrust force, torque, temperature increase during drilling, and chip morphology. Both axial thrust force and torque were significantly higher for the aluminum alloy but were independent of the cutting speed for both materials. However, both increased linearly with increasing feed rate for the composite, but nonlinearly for the aluminum alloy. The Shaw-Oxford equation for predicting axial thrust and torque worked well with the aluminum alloy but did not fit the composite’s axial thrust and torque characteristics. Both materials exhibited temperature rise at locations close to the drilled hole. The temperature rise decreased with increasing feed rate as well as increasing cutting speed; however, the maximum temperature rise in the composite was significantly lower than that in the aluminum alloy. There was also a significant difference in the morphology of chips of these two materials.
26
Wang, Qingyan, Hongzhong Ma, Shengrang Cao, and Bingyan Chen. "Structure Optimal Design of Electromagnetic Levitation Load Reduction Device for Hydroturbine Generator Set." Mathematical Problems in Engineering 2015 (2015): 1–5. http://dx.doi.org/10.1155/2015/814084.
Full textAbstract:
Thrust bearing is one part with the highest failure rate in hydroturbine generator set, which is primarily due to heavy axial load. Such heavy load often makes oil film destruction, bearing friction, and even burning. It is necessary to study the load and the reduction method. The dynamic thrust is an important factor to influence the axial load and reduction design of electromagnetic device. Therefore, in the paper, combined with the structure features of vertical turbine, the hydraulic thrust is analyzed accurately. Then, take the turbine model HL-220-LT-550, for instance; the electromagnetic levitation load reduction device is designed, and its mathematical model is built, whose purpose is to minimize excitation loss and total quality under the constraints of installation space, connection layout, and heat dissipation. Particle swarm optimization (PSO) is employed to search for the optimum solution; finally, the result is verified by finite element method (FEM), which demonstrates that the optimized structure is more effective.
27
NAKAJIMA, Tomomi, Yoshio SHIKANO, and Yutaka YAMASHITA. "318 Prediction of Unsteady Force for Axial Turbine Buckets." Proceedings of Ibaraki District Conference 2012.20 (2012): 91–92. http://dx.doi.org/10.1299/jsmeibaraki.2012.20.91.
Full text
28
LIU, Hongwei. "Axial Thrust Analysis of Ocean Current Turbine and Design of Hydraulic Equilibrator." Journal of Mechanical Engineering 45, no. 12 (2009): 70. http://dx.doi.org/10.3901/jme.2009.12.070.
Full text
29
Bagheri-Sadeghi, Nojan, Brian T. Helenbrook, and Kenneth D. Visser. "Maximal power per device area of a ducted turbine." Wind Energy Science 6, no. 4 (July 29, 2021): 1031–41. http://dx.doi.org/10.5194/wes-6-1031-2021.
Full textAbstract:
Abstract. The aerodynamic design of a ducted wind turbine for maximum total power coefficient was studied numerically using the axisymmetric Reynolds-averaged Navier–Stokes equations and an actuator disc model. The total power coefficient characterizes the rotor power per total device area rather than the rotor area. This is a useful metric to compare the performance of a ducted wind turbine with an open rotor and can be an important design objective in certain applications. The design variables included the duct length, the rotor thrust coefficient, the angle of attack of the duct cross section, the rotor gap, and the axial location of the rotor. The results indicated that there exists an upper limit for the total power coefficient of ducted wind turbines. Using an Eppler E423 airfoil as the duct cross section, an optimal total power coefficient of 0.70 was achieved at a duct length of about 15 % of the rotor diameter. The optimal thrust coefficient was approximately 0.9, independent of the duct length and in agreement with the axial momentum analysis. Similarly independent of duct length, the optimal normal rotor gap was found to be approximately the duct boundary layer thickness at the rotor. The optimal axial position of the rotor was near the rear of the duct but moved upstream with increasing duct length, while the optimal angle of attack of the duct cross section decreased.
30
Dring, R. P. "Radial Mixing in an Axial Turbine." Journal of Turbomachinery 118, no. 2 (April 1, 1996): 262–67. http://dx.doi.org/10.1115/1.2836635.
Full textAbstract:
The objective of this work was to examine radial mixing in an axial turbine from a number of different perspectives. These include: (1) its impact on the spanwise distributions of the force on the airfoils and the change in the fluid momentum as it passed between them, (2) the mixing coefficient distribution based on measured secondary flow velocities, and (3) comparisons of measured and calculated profile redistribution for an axisymmetric inlet profile and for profiles generated by introducing hot and cold streaks upstream of the turbine. It was seen that a simple diffusive transport model could give a good prediction of most of the measured results.
31
Teo, C. J., and Z. S. Spakovszky. "Modeling and Experimental Investigation of Micro-hydrostatic Gas Thrust Bearings for Micro-turbomachines." Journal of Turbomachinery 128, no. 4 (February 1, 2005): 597–605. http://dx.doi.org/10.1115/1.2219760.
Full textAbstract:
One major challenge for the successful operation of high-power-density micro-devices lies in the stable operation of the bearings supporting the high-speed rotating turbomachinery. Previous modeling efforts by Piekos (2000, “Numerical Simulation of Gas-Lubricated Journal Bearings for Microfabricated Machines,” Ph.D. thesis, Department of Aeronautics and Astronautics, MIT), Liu et al. (2005, “Hydrostatic Gas Journal Bearings for Micro-Turbo Machinery,” ASME J. Vib. Acoust., 127, pp. 157–164), and Spakovszky and Liu (2005, “Scaling Laws for Ultra-Short Hydrostatic Gas Journal Bearings,” ASME J. Vib. Acoust. 127, pp. 254–261) have focused on the operation and stability of journal bearings. Thrust bearings play a vital role in providing axial support and stiffness, and there is a need to improve the understanding of their dynamic behavior. In this work, a rigorous theory is presented to analyze the effects of compressibility in micro-flows (characterized by low Reynolds numbers and high Mach numbers) through hydrostatic thrust bearings for application to micro-turbomachines. The analytical model, which combines a one-dimensional compressible flow model with finite-element analysis, serves as a useful tool for establishing operating protocols and assessing the stability characteristics of hydrostatic thrust bearings. The model is capable of predicting key steady-state performance indicators, such as bearing mass flow, axial stiffness, and natural frequency as a function of the hydrostatic supply pressure and thrust-bearing geometry. The model has been applied to investigate the static stability of hydrostatic thrust bearings in micro-turbine generators, where the electrostatic attraction between the stator and rotor gives rise to a negative axial stiffness contribution and may lead to device failure. Thrust-bearing operating protocols have been established for a micro-turbopump, where the bearings also serve as an annular seal preventing the leakage of pressurized liquid from the pump to the gaseous flow in the turbine. The dual role of the annular pad poses challenges in the operation of both the device and the thrust bearing. The operating protocols provide essential information on the required thrust-bearing supply pressures and axial gaps required to prevent the leakage of water into the thrust bearings. Good agreement is observed between the model predictions and experimental results. A dynamic stability analysis has been conducted, which indicates the occurrence of instabilities due to flow choking effects in both forward and aft thrust bearings. A simple criterion for the onset of axial rotor oscillations has been established and subsequently verified in a micro-turbocharger experiment. The predicted frequencies of the unstable axial oscillations compare well with the experimental measurements.
32
Yang, Cong Xin, Yi Xiong Liu, and Bin Wang. "Buckling Analysis on Large Wind Turbine Tower." Advanced Materials Research 512-515 (May 2012): 604–7. http://dx.doi.org/10.4028/www.scientific.net/amr.512-515.604.
Full textAbstract:
The buckling of 2.5MW horizontal axis wind turbine tower tube (5.8m*3.2m*95.2m) is studied by theoretical analysis and numerical simulation. The buckling critical value of tower under axial force is found by theoretical method. The buckling modal of tower under axial force, wind pressure, bending moment and lateral force is simulated by ANSYS software. The buckling of tower with opening and frame at the bottom is also simulated by ANSYS software. The results show that both load and opening have influence on buckling performance, different load and opening have different impact to buckling of tower tube.
33
San Andre´s, Luis. "Effects of Misalignment on Turbulent Flow Hybrid Thrust Bearings." Journal of Tribology 124, no. 1 (May 3, 2001): 212–19. http://dx.doi.org/10.1115/1.1400997.
Full textAbstract:
An extended computational bulk-flow analysis for prediction of performance in angled injection, orifice-compensated hydrostatic/hydrodynamic thrust bearings is presented. The fluid motion within the thin film lands is governed by mass conservation and momentum transport equations. Mass flow conservation and a simple model for momentum transport within the hydrostatic bearing recesses are also accounted for. A perturbation analysis for small amplitude shaft axial motions and angulations leads to zeroth and first-order equations describing the equilibrium and perturbed fluid flows. The computational procedure predicts the bearing flow rate, thrust load and restoring moments, drag torque, and 27 force and moment coefficients. The effects of misalignment on the dynamic performance of a refrigerant fluid-hybrid thrust bearing are evaluated at an optimal operating condition. The axial force/displacement stiffness coefficient and the direct moment/angle stiffness coefficients show a maximum for a certain recess pressure ratio, while the damping coefficient steadily increases with the applied load. As the misalignment angle increases, both moment and force coefficients also increase. Most operating conditions show a whirl frequency ratio equal to 0.50. Thus, thrust hybrid bearings offer the same limited stability characteristics as hydrodynamic thrust bearings when undergoing self-excited shaft angular motions.
34
Comyn, Graeme I., David S. Nobes, and Brian A. Fleck. "PERFORMANCE EVALUATION AND WAKE STUDY OF A MICRO WIND TURBINE." Transactions of the Canadian Society for Mechanical Engineering 35, no. 1 (March 2011): 101–17. http://dx.doi.org/10.1139/tcsme-2011-0007.
Full textAbstract:
In preparation for a study on icing of wind turbine blades, we tested a horizontal axis micro wind turbine in a low speed wind tunnel. The ratio of wind turbine rotor area to wind tunnel cross-sectional area resulted in highly blocked experimental configuration. The turbine was instrumented to measure rotational speed of the rotor, axial thrust and power output. Performance characteristics were calculated and compared with the manufacturer’s published data. In addition, the near wake of the turbine was measured with a Kiel probe. One dimensional axial momentum theory, including a modification that includes channel walls, was applied to determine power extracted from the wind by the rotor. The results were compared to actual power output and show that though the assumptions of the model over-predict power by 50 % the basic trend is followed.
35
Flores Mateos, Lilia, and Michael Hartnett. "Incorporation of a Non-Constant Thrust Force Coefficient to Assess Tidal-Stream Energy." Energies 12, no. 21 (October 31, 2019): 4151. http://dx.doi.org/10.3390/en12214151.
Full textAbstract:
A novel method for modelling tidal-stream energy capture at the regional scale is used to evaluate the performance of two marine turbine arrays configured as a fence and a partial fence. These configurations were used to study bounded and unbounded flow scenarios, respectively. The method implemented uses turbine operating conditions (TOC) and the parametrisation of changes produced by power extraction within the turbine near-field to compute a non-constant thrust coefficient, and it is referred to as a momentum sink TOC. Additionally, the effects of using a shock-capture capability to evaluate the resource are studied by comparing the performance of a gradually varying flow (GVF) and a rapidly varying flow (RVF) solver. Tidal-stream energy assessment of bounded flow scenarios through a full fence configuration is better performed using a GVF solver, because the head drop is more accurately simulated; however, the solver underestimates velocity reductions due to power extraction. On the other hand, assessment of unbounded flow scenarios through a partial fence was better performed by the RVF solver. This scheme approximated the head drop and velocity reduction more accurately, thus suggesting that resource assessment with realistic turbine configurations requires the correct solution of the discontinuities produced in the tidal-stream by power extraction.
36
Yuan, Z., F. Chu, R. Hao, and S. Wang. "Clearance-excitation force of shrouded turbine rotor accounting for pitching motion." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 221, no. 2 (February 1, 2007): 187–94. http://dx.doi.org/10.1243/0954406jmes284.
Full textAbstract:
Based on the basic mechanism of turbine rotor's clearance-excitation force and the motion patterns of turbine wheel, a new comprehensive leakage flow mechanism for shrouded turbine rotors is presented by taking into account both the radial and axial clearance variations due to rotor's whirling and pitching motions. According to this mechanism, a comprehensive analytical expression for clearance-excitation force of shrouded turbine rotor is developed. The developed expression reflects both the whirling eccentricity and the pitching angle of turbine rotor, and embodies the mean radial and axial clearances as well. Validations are performed to verify the effectiveness of the present expression. Numerical analyses are conducted to demonstrate the properties of the present clearance-excitation force. It is concluded that the present clearance-excitation force expression not only improves the classical one quantitatively, but also discloses the weak non-linearity of the clearance-excitation force. This is proved to be useful in the analyses of complicated rotordynamic systems where several non-linear factors couple together.
37
Zhang, Wanchao, Yujie Zhou, Kai Wang, and Xiaoguo Zhou. "Forced Motion CFD Simulation and Load Refinement Evaluation of Floating Vertical-Axis Tidal Current Turbines." Polish Maritime Research 27, no. 3 (September 1, 2020): 40–49. http://dx.doi.org/10.2478/pomr-2020-0045.
Full textAbstract:
AbstractSimulation of the hydrodynamic performance of a floating current turbine in a combined wave and flow environment is important. In this paper, ANSYS-CFX software is used to analyse the hydrodynamic performance of a vertical-axis turbine with various influence factors such as tip speed ratio, pitching frequency and amplitude. Time-varying curves for thrust and lateral forces are fitted with the least squares method; the added mass and damping coefficients are refined to analyse the influence of the former factors. The simulation results demonstrate that, compared with non-pitching and rotating turbines under constant inflow, the time-varying load of rotating turbines with pitching exhibits an additional fluctuation. The pitching motion of the turbine has a positive effect on the power output. The fluctuation amplitudes of thrust and lateral force envelope curves have a positive correlation with the frequency and amplitude of the pitching motion and tip speed ratio, which is harmful to the turbine’s structural strength. The mean values of the forces are slightly affected by pitching frequencies and amplitudes, but positively proportional to the tip speed ratio of the turbine. Based upon the least squares method, the thrust and lateral force coefficients can be divided into three components, uniform load coefficient, added mass and damping coefficients, the middle one being significantly smaller than the other two. Damping force plays a more important role in the fluctuation of loads induced by pitching motion. These results can facilitate study of the motion response of floating vertical-axis tidal current turbine systems in waves.
38
Karaskiewicz, Krzysztof, and Marek Szlaga. "Experimental and Numerical Investigation of Radial Forces Acting on Centrifugal Pump Impeller." Archive of Mechanical Engineering 61, no. 3 (December 10, 2014): 445–54. http://dx.doi.org/10.2478/meceng-2014-0025.
Full textAbstract:
Abstract The paper presents the results of measurements and predictions of radial thrust in centrifugal pump with specific speed ns = 26. In the pump tested, a volute with rectangular cross-section was used. The tests were carried out for several rotational speeds, including speeds above and below the nominal one. Commercial code ANSYS Fluent was used for the calculations. Apart from the predictions of the radial force, the calculations of axial thrust were also conducted, and correlation between thrust and the radial force was found. In the range of the measured rotational speeds, similarity of radial forces was checked.
39
Makhdum, Farrukh, Dk Nurdiyana Pg Norddin, Anish Roy, and Vadim V. Silberschmidt. "Ultrasonically Assisted Drilling of Carbon Fibre Reinforced Plastics." Solid State Phenomena 188 (May 2012): 170–75. http://dx.doi.org/10.4028/www.scientific.net/ssp.188.170.
Full textAbstract:
Carbon fibre-reinforced plastics (CFRPs) gained substantial acclaim in recent decades and are used in aerospace, automotive and structural applications due to their high strength-to-weight ratio, high stiffness, high fatigue and corrosion resistance. CFRPs are manufactured near to net shape but some machining processes such as drilling cannot be avoided. Drilling induces damage (delamination, matrix cracking, matrix burning, lamina cracking and fibre pull out) in CFRP because of high axial thrust forces and a temperature rise. In this research an attempt is made to use ultrasonically assisted drilling (UAD) to reduce the axial thrust forces. In UAD high frequency (~ 20 kHz) vibrations are superimposed on a drill bit, preferably in axial direction, to reduce the thrust forces. In this study, experiments are conducted in two stages. At the first stage an initial setup with an existing UAD transducer is used to compare UAD with conventional drilling (CD) of CFRP. A reduced thrust force is experienced in case of UAD when compared to CD. At the second stage, drilling dynamics, i.e. feed speed, is changed along with the improvement of the transducer, and an enormous amount of force reduction (>80%) is observed in case of UAD (as compared to CD).
40
Kumar, P. Santhana, R. Joseph Bensingh, and A. Abraham. "Computational Analysis of 30 Kw Contra Rotor Wind Turbine." ISRN Renewable Energy 2012 (August 16, 2012): 1–5. http://dx.doi.org/10.5402/2012/939878.
Full textAbstract:
The aim of this study is to optimize and analyze the characteristics of the upwind primary rotor and the downwind secondary rotor of the contra rotor wind turbine to increase the aerodynamic performance by using computational fluid dynamic (CFD). The main objective is to provide maximum energy that can be extracted by the primary and secondary rotor from the renewable resource of wind to increase the thrust power. For this purpose, two kinds of rotor configurations which are 3-bladed single and 3-bladed contra-rotating rotor were compared by using CFD. The results of the primary and secondary rotor are validated with measurements of the 30 KW Contra rotor wind turbine available on literature and plotted for power output. The optimum axial distance between the two rotors are investigated through CFD for increased performance. In addition, the increased thrust and torque for each rotor configuration are compared for aerodynamic feasibility.
41
Dong, Song, Wenhe Liao, Kan Zheng, and Wenrui Ma. "Investigation on thrust force in rotary ultrasonic drilling of CFRP/aluminum stacks." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, no. 2 (September 24, 2019): 394–404. http://dx.doi.org/10.1177/0954406219877209.
Full textAbstract:
The stacks of carbon fiber-reinforced polymer (CFRP) and aluminum are widely used in aviation industry due to its excellent mechanical and physical properties. Recently, rotary ultrasonic drilling technology which is recognized as a useful machining method has been introduced to machining these stacks. Thrust force influences the machinability directly such as tool wear, cutting temperature, and hole qualities. In this study, a theoretical model of thrust force for rotary ultrasonic drilling of CFRP/aluminum stacks is proposed. Based on the analysis of kinematic characteristics, the axial uncut chip thickness of rotary ultrasonic drilling is presented. Then the whole machining process of stacks is divided into five different states. Forces on cutting edge and chisel edge in different materials are modeled, respectively. After that, the thrust forces of five-state rotary ultrasonic drilling process are achieved by integrating with integral limits analysis in each state. Finally, verification experiments are conducted, and experimental results show that the trends of thrust forces agree well with the thrust force model. Therefore, this theoretical model can be used to evaluate the thrust force in rotary ultrasonic drilling of CFRP/aluminum stacks.
42
Eryilmaz, I., L. Pawsey, and V. Pachidis. "Multidisciplinary methodology for turbine overspeed analysis." Aeronautical Journal 122, no. 1257 (November 2018): 1711–33. http://dx.doi.org/10.1017/aer.2018.100.
Full textAbstract:
ABSTRACTIn this paper, an integrated approach to turbine overspeed analysis is presented, taking into account the secondary air system dynamics and mechanical friction in a turbine assembly following an unlocated high-pressure shaft failure. The axial load acting on the rotating turbine assembly is a governing parameter in terms of overspeed protection since it governs the level of mechanical friction which acts against the turbine acceleration due to gas torque. The axial load is dependent on both the force coming from secondary air system cavities surrounding the disc and the force on the rotor blades. It is highly affected by secondary air system dynamics because rotor movement modifies the geometry of seals and flow paths within the network. As a result, the primary parameters of interest in this study are the axial load on the turbine rotor, the friction torque between rotating and static structures and the axial position of the rotor.Following an initial review of potential damage scenarios, several cases are run to establish the effect of each damage scenario and variable parameter within the model, with comparisons being made to a baseline case in which no interactions are modelled. This allows important aspects of the secondary air system to be identified in terms of overspeed prevention, as well as guidelines on design changes in current and future networks that will be beneficial for overspeed prevention.
43
Wang, Jiabao, Shoudao Huang, Chao Guo, and Yaojing Feng. "Research on the Axial Force of Conical-Rotor Permanent Magnet Synchronous Motors with Turbines." Energies 11, no. 10 (September 22, 2018): 2532. http://dx.doi.org/10.3390/en11102532.
Full textAbstract:
The general method to suppress the axial force of the permanent magnet synchronous motor (PMSM) direct-drive turbine is to increase the number of balance devices, such as balance disks and special bearings, to counteract its influence, but this also leads to complex system structure and higher mechanical losses. Aiming to solve the above issue, this paper presents a novel PMSM structure with a conical-rotor (CR). Due to its adaptive equilibrium of axial force and simple structure of rotor with turbine, the CR-PMSM can help improve the system efficiency. Both surface-type and interior-type motors are analyzed, and the axial magnetic force of CR-PMSM is studied in detail. The 3-D finite-element method (FEM) is used to model and simulate the machine, and the magnetic-field distribution, axial magnetic force and driving performance are obtained. Also, the control rule of d-axis current is analyzed to achieve the adaptive equilibrium of axial force. A 2.0 kW, 6000 r/min prototype motor is fabricated and tested to validate the theory.
44
Bagheri-Sadeghi, Nojan, Brian T. Helenbrook, and Kenneth D. Visser. "Ducted wind turbine optimization and sensitivity to rotor position." Wind Energy Science 3, no. 1 (April 25, 2018): 221–29. http://dx.doi.org/10.5194/wes-3-221-2018.
Full textAbstract:
Abstract. The design of a ducted wind turbine modeled using an actuator disc was studied using Reynolds-averaged Navier–Stokes (RANS) computational fluid dynamics (CFD) simulations. The design variables included the rotor thrust coefficient, the angle of attack of the duct cross section, the radial gap between the rotor and the duct, and the axial location of the rotor in the duct. Two different power coefficients, the rotor power coefficient (based on the rotor swept area) and the total power coefficient (based on the exit area of the duct), were used as optimization objectives. The optimal value of thrust coefficients for all designs was nearly constant, having a value between 0.9 and 1. The rotor power coefficient was sensitive to rotor gap but was insensitive to the rotor's axial location for positions ranging from upstream of the throat to nearly half the distance down the duct. Compared to the design that maximized rotor power coefficient, the design for maximal total power coefficient was characterized by a smaller angle of attack, a smaller rotor gap, and a downstream placement of the rotor. The insensitivity of power output to the rotor position implies that a rotor placed further downstream in the duct could produce the same power with a considerably smaller duct exit area and thus a greater total power coefficient. The design for that maximized total power coefficient exceeded Betz's limit with a total power coefficient of 0.67.
45
Nishi, Yasuyuki, and Junichiro Fukutomi. "Effect of Blade Outlet Angle on Unsteady Hydrodynamic Force of Closed-Type Centrifugal Pump with Single Blade." International Journal of Rotating Machinery 2014 (2014): 1–16. http://dx.doi.org/10.1155/2014/838627.
Full textAbstract:
Geometrically, the single-blade centrifugal impeller, commonly used today as a sewage pump, is not axially symmetric. For this reason, the static pressure around the impeller fluctuates greatly when the impeller is rotating, and not only the radial thrust but also the axial thrust shows large fluctuations. Therefore, it is extremely important for the improvement of pump reliability to quantitatively grasp these fluctuating hydrodynamic forces. In this study, we investigated the unsteady hydrodynamic forces in a closed-type centrifugal pump with a single blade for different blade outlet angles using a numerical analysis that takes into account both experiment and the leakage flow. The results clearly showed the effect of the blade outlet angle on that act on the impeller. The root-mean-square value of the fluctuating component of the total radial thrust was roughly the same for whichever impeller at low flow rate, but at high flow rates, the value increased for impellers with larger blade outlet angles. Moreover, when the leakage flow rate increased with increasing static pressure around the impeller, such that the rear and front shroud parts were subject to high pressure, the absolute value of the axial thrust on both these parts increased.
46
Szczęch, Marcin, Wojciech Horak, and Yuliia Tarasevych. "NUMERICAL ANALYSIS OF OPERATING PARAMETERS OF HYDRODYNAMIC THRUST BEARINGS LUBRICATED WITH MAGNETIC FLUID." Tribologia 291, no. 3 (June 30, 2020): 43–51. http://dx.doi.org/10.5604/01.3001.0014.4764.
Full textAbstract:
The paper presents the results of numerical simulations (CFD) of hydrodynamic thrust slide bearings lubricated with magnetorheological (MR) fluid. The analyses were carried out to evaluate the influence of the rheological properties of the lubricant, as well as the geometry of the bearing's thrust pad surface. Bearing load conditions were considered on the key functional features of the system, i.e. axial force and torque. The paper presents a comparative analysis of various geometries of thrust bearings and points out possible functional features of hydrodynamic thrust bearings lubricated with fluids with controlled rheological properties.
47
Ghaisas, Niranjan S., Aditya S. Ghate, and Sanjiva K. Lele. "Effect of tip spacing, thrust coefficient and turbine spacing in multi-rotor wind turbines and farms." Wind Energy Science 5, no. 1 (January 6, 2020): 51–72. http://dx.doi.org/10.5194/wes-5-51-2020.
Full textAbstract:
Abstract. Large eddy simulations (LESs) are performed to study the wakes of a multi-rotor wind turbine configuration comprising four identical rotors mounted on a single tower. The multi-rotor turbine wakes are compared to the wake of a conventional turbine comprising a single rotor per tower with the same frontal area, hub height and thrust coefficient. The multi-rotor turbine wakes are found to recover faster, while the turbulence intensity in the wake is smaller, compared to the wake of the conventional turbine. The differences with the wake of a conventional turbine increase as the spacing between the tips of the rotors in the multi-rotor configuration increases. The differences are also sensitive to the thrust coefficients used for all rotors, with more pronounced differences for larger thrust coefficients. The interaction between multiple multi-rotor turbines is contrasted with that between multiple single-rotor turbines by considering wind farms with five turbine units aligned perfectly with each other and with the wind direction. Similar to the isolated turbine results, multi-rotor wind farms show smaller wake losses and smaller turbulence intensity compared to wind farms comprised of conventional single-rotor turbines. The benefits of multi-rotor wind farms over single-rotor wind farms increase with increasing tip spacing, irrespective of the axial spacing and thrust coefficient. The mean velocity profiles and relative powers of turbines obtained from the LES results are predicted reasonably accurately by an analytical model assuming Gaussian radial profiles of the velocity deficits and a hybrid linear-quadratic model for the merging of wakes. These results show that a larger power density can be achieved without significantly increased fatigue loads by using multi-rotor turbines instead of conventional, single-rotor turbines.
48
Svorcan, Jelena, Ognjen Pekovic, and Toni Ivanov. "Estimation of wind turbine blade aerodynamic performances computed using different numerical approaches." Theoretical and Applied Mechanics 45, no. 1 (2018): 53–65. http://dx.doi.org/10.2298/tam171130004s.
Full textAbstract:
Although much employed, wind energy systems still present an open, contemporary topic of many research studies. Special attention is given to precise aerodynamic modeling performed in the beginning since overall wind turbine performances directly depend on blade aerodynamic performances. Several models different in complexity and computational requirements are still widely used. Most common numerical approaches include: i) momentum balance models, ii) potential flow methods and iii) full computational fluid dynamics solutions. Short explanations, reviews and comparison of the existing computational concepts are presented in the paper. Simpler models are described and implemented while numerous numerical investigations of isolated horizontal-axis wind turbine rotor consisting of three blades have also been performed in ANSYS FLUENT 16.2. Flow field is modeled by Reynolds Averaged Navier-Stokes (RANS) equations closed by two different turbulence models. Results including global parameters such as thrust and power coefficients as well as local distributions along the blade obtained by different models are compared to available experimental data. Presented results include fluid flow visualizations in the form of velocity contours, sectional pressure distributions and values of power and thrust force coefficients for a range of operational regimes. Although obtained numerical results vary in accuracy, all presented numerical settings seem to slightly under- or over-estimate the global wind turbine parameters (power and thrust force coefficients). Turbulence can greatly affect the wind turbine aerodynamics and should be modeled with care.
49
Da˛browski, Leszek, and Michał Wasilczuk. "A Method of Friction Torque Measurement for a Hydrodynamic Thrust Bearing." Journal of Tribology 117, no. 4 (October 1, 1995): 674–78. http://dx.doi.org/10.1115/1.2831534.
Full textAbstract:
Measurements of thrust bearing friction torque are difficult because of the small values of the friction force in comparison with the axial load. Another problem of a thrust bearing test rig design is the necessity of accommodation of the axial load so that it does not interact with the frictional forces. Separation of fluid drag in the housing from torque in the bearing itself is also important. An analysis of a design in which the above-mentioned problems have been solved is presented. Theoretical analysis and calibration of the torque meter proved that the effect of axial load was successfully compensated for. Example of the results obtained due to the torque meter illustrate the application of the new design.
50
Gao, Yong Qiang, Jin Qiu Zhang, Jie Yue, and Zhi Zhao Peng. "Design and Damping Force Analysis for Turbine Composite Regenerative Damper." Advanced Materials Research 446-449 (January 2012): 1360–65. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.1360.
Full textAbstract:
Turbine composite regenerative damper is one of new type damper which can regenerate the energy of vibration. The component and principle of generator and regenerate energy for turbine composite regenerative damper is introduce, and based on hydrodynamics and axial turbine basic principle, the relationship between induced electromotive force and piston velocity ,load resistance is induced. At last, the relationship between damping force and piston velocity, load resistance is induced too. The method is meaningful to understand and instruct the design of turbine composite regenerative damper.