To see the other types of publications on this topic, follow the link: Rotor flows.
Journal articles on the topic 'Rotor flows'
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 'Rotor flows.'
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
STATSENKO, V., O. BURMISTENKOV, and T. BILA. "DETERMINATION OF THE BULK MATERIALS PARTICLES DISTRIBUTION DURING MIXING IN THE CONTINUOUS ACTION CENTRIFUGAL MIXERS ROTOR." Herald of Khmelnytskyi National University. Technical sciences 281, no. 1 (2020): 238–44. http://dx.doi.org/10.31891/2307-5732-2020-281-1-238-244.
Full textAbstract:
The article presents the results of the bulk materials particles movement study in continuous centrifugal mixers with conical rotors. Mathematical models of particle motion in the rotor are developed. The systems of differential equations that describe the particles motion on the rotor bottom and side surface are given. Particle trajectories are shown. The effect of the particle flow initial position in the rotor on the particles distribution at the rotor exit is studied. A relationship is established between the particles distribution at the rotor exit and the mixture homogeneity, which was estimated using the coefficient of variation. The mathematical modelling results of a two-component mixture particles distribution under various initial motion conditions of these components are presented. Four variants of the mixture components movement inside the rotor are considered. The initial conditions for the particles motion differed in the initial components flows position at the rotor bottom, as well as in these flows number. For all cases, histograms of the particles distribution along the rotor outer edge with a 150 step were plotted. In all zones, the particles number of each mixture component was calculated and its percentage composition was determined. Based on the data obtained, the mixture homogeneity was determined. It was found that the mixture homogeneity increases with a decrease in the difference between the particles flows initial motion conditions in the rotor. It was also found that dividing the flows into parts increases the mixture uniformity.
2
Frontin, Cory, Ganesh Vijayakumar, and Pietro Bortolotti. "Aerodynamic and production comparison of wind farms with downwind versus conventional upwind turbines." Journal of Physics: Conference Series 2767, no. 9 (2024): 092008. http://dx.doi.org/10.1088/1742-6596/2767/9/092008.
Full textAbstract:
Abstract Ever-increasing turbine scales and their associated logistical challenges have reignited questions about the performance of downwind rotor configurations. A particular potential benefit of downwind rotor configurations is the farm-scale power increase that may be conferred by tilt-driven downward wake entrainment and associated wake recovery. In this work, a comprehensive aerodynamic analysis is carried out to understand the mechanisms for wake entrainment and recovery across a spectrum of velocity and inflow alignment conditions on a small, structured farm in order to understand the impact of downwind rotors on farm production. The results show that the benefits demonstrated previously in the literature for downwind-rotor farms in aligned flows are fragile, and, outside of strong farm/flow alignment conditions, power production benefits for small farms with downwind rotor configurations are significantly if not completely mitigated by misalignment effects. The work indicates that farm-scale benefits for downwind rotors must be realized either from large-scale entrainment benefits, with more exotic farm arrangements that can take advantage of the aerodynamic effects, or from beneficial fatigue impacts from entrainment of less turbulent outer boundary layer flows.
3
Hah, C., and A. J. Wennerstrom. "Three-Dimensional Flowfields Inside a Transonic Compressor With Swept Blades." Journal of Turbomachinery 113, no. 2 (1991): 241–50. http://dx.doi.org/10.1115/1.2929092.
Full textAbstract:
The concept of swept blades for a transonic or supersonic compressor was reconsidered by Wennerstrom in the early 1980s. Several transonic rotors designed with swept blades have shown very good aerodynamic efficiency. The improved performance of the rotor is believed to be due to reduced shock strength near the shroud and better distribution of secondary flows. A three-dimensional flowfield inside a transonic rotor with swept blades is analyzed in detail experimentally and numerically. A Reynolds-averaged Navier–Stokes equation is solved for the flow inside the rotor. The numerical solution is based on a high-order upwinding relaxation scheme, and a two-equation turbulence model with a low Reynolds number modification is used for the turbulence modeling. To predict flows near the shroud properly, the tip-clearance flow also must be properly calculated. The numerical results at three different operating conditions agree well with the available experimental data and reveal various interesting aspects of shock structure inside the rotor.
4
Van Zante, Dale E., Anthony J. Strazisar, Jerry R. Wood, Michael D. Hathaway, and Theodore H. Okiishi. "Recommendations for Achieving Accurate Numerical Simulation of Tip Clearance Flows in Transonic Compressor Rotors." Journal of Turbomachinery 122, no. 4 (1999): 733–42. http://dx.doi.org/10.1115/1.1314609.
Full textAbstract:
The tip clearance flows of transonic compressor rotors are important because they have a significant impact on rotor and stage performance. A wall-bounded shear layer formed by the relative motion between the overtip leakage flow and the shroud wall is found to have a major influence on the development of the tip clearance flow field. This shear layer, which has not been recognized by earlier investigators, impacts the stable operating range of the rotor. Simulation accuracy is dependent on the ability of the numerical code to resolve this layer. While numerical simulations of these flows are quite sophisticated, they are seldom verified through rigorous comparisons of numerical and measured data because these kinds of measurements are rare in the detail necessary to be useful in high-speed machines. In this paper we compare measured tip-clearance flow details (e.g., trajectory and radial extent) with corresponding data obtained from a numerical simulation. Laser-Doppler Velocimeter (LDV) measurements acquired in a transonic compressor rotor, NASA Rotor 35, are used. The tip clearance flow field of this transonic rotor is simulated using a Navier–Stokes turbomachinery solver that incorporates an advanced k–ε turbulence model derived for flows that are not in local equilibrium. A simple method is presented for determining when the wall-bounded shear layer is an important component of the tip clearance flow field. [S0889-504X(00)02504-6]
5
Freitas, Felipe Augusto Lustosa Meireles, Ronaldo Barcelos e. Silva, Leonardo Da Rosa Schmidt, Silvana Maldaner, and Lucinéia Fabris. "Análise da potência mecânica de rotores de Savonius de mesma razão de aspecto." Ciência e Natura 42 (February 7, 2020): 33. http://dx.doi.org/10.5902/2179460x40635.
Full textAbstract:
An experimental performance study of Savonius small rotors is performed in this work. Two Savonius prototypes, two blades and the same aspect ratio, were constructed from vinyl polychloride and use different air flow. Experimental tests allowed the rotation speed of each rotor to be determined for different air flows. It is important to note that the average angular velocity of the smaller rotor is approximately fifty percent higher than the larger rotor. At the same time, the absorption torque on the rotor shaft was measured and the mechanical power of each Savonius wind turbine prototype was estimated. The main result was that wind turbines of the same aspect ratio have different performances.
6
Redchyts, Dmytro, Koldo Portal-Porras, Serhii Tarasov, et al. "Aerodynamic Performance of Vertical-Axis Wind Turbines." Journal of Marine Science and Engineering 11, no. 7 (2023): 1367. http://dx.doi.org/10.3390/jmse11071367.
Full textAbstract:
The nonstationary separated incompressible flows around Darrieus and Savonius rotors of vertical-axis wind turbines were investigated through computational simulation using the Reynolds averaged Navier–Stokes equations and Spalart–Allmaras turbulence model. The implicit finite-volume algorithm, the basis of which was artificial compressibility method, was chosen to obtain the numerical solution. The series of computational and physical experiments for Darrieus rotors with varied numbers and shapes of blades were performed. The detailed visualization of the flow was presented. The turbulent flows surrounding the Darrieus and Savonius rotors were studied, and as a part of these investigations, the major phases of vortex progress were identified. For this purpose, three series of computer tests on the aerodynamic and power properties of Savonius rotors with two and three buckets were performed, and their results are also presented. The influence of tip-speed ratio, solidity, and Reynolds numbers on the power coefficients of the Darrieus and Savonius rotors was investigated. It has been demonstrated that increasing Reynolds number from 104 to 106 causes a rise in Darrieus rotors power coefficient from 0.15 up to 0.5. The maximum values of power coefficient are moved away from higher values of tip-speed ratio from 2 to 5 as a result of a decrease in Darrieus rotor solidity from 1.0 to 0.33. The greatest power coefficient for a Savonius rotor with two blades is 0.23 and for a Savonius rotor with three blades is 0.19.
7
Koya, M., and S. Kotake. "Numerical Analysis of Fully Three-Dimensional Periodic Flows Through a Turbine Stage." Journal of Engineering for Gas Turbines and Power 107, no. 4 (1985): 945–52. http://dx.doi.org/10.1115/1.3239840.
Full textAbstract:
Fully three-dimensional periodic flows through a turbine stage of stator and rotor are studied numerically by solving time-dependent three-dimensional Euler equations with the finite-volume method. The phase relation of stator and rotor flows and the related blade-row interaction are accounted for in the time-space domain. The established method of numerical calculation makes a practical contribution to predict actual turbine flows through a turbine stage of stator and rotor which have an arbitrary number of blades.
8
Arndt, N. "Blade Row Interaction in a Multistage Low-Pressure Turbine." Journal of Turbomachinery 115, no. 1 (1993): 137–46. http://dx.doi.org/10.1115/1.2929198.
Full textAbstract:
The objective of this work was to enhance the understanding of unsteady flow phenomena in multistage low-pressure turbines. For this purpose, hot-film probe measurements were made downstream of every rotor blade row of a five-stage low-pressure turbine. Rotor–rotor interaction and stator–rotor interaction were observed to have a profound influence on the flow through the low-pressure turbine. Interaction of rotors of different turbine stages occurred owing to the influence of the wakes shed by one rotor blade row upon the flow through the next downstream rotor blade row. This wake-induced rotor–rotor interaction resulted in strongly amplitude-modulated periodic and turbulent velocity fluctuations downstream of every rotor blade row with the exception of the most upstream one. Significantly different wake depths and turbulence levels measured downstream of every rotor blade row at different circumferential positions evidenced the effect of the circumferentially nonuniform stator exit flow upon the next downstream rotor blade row. Stator-rotor interaction also strongly influenced the overturning and the under-turning of the rotor wakes, caused by the rotor secondary flows, in the rotor endwall regions. Low rotor wake overturning and underturning, i.e., reduced rotor secondary flow influence, were observed to correlate well with low rotor wake turbulence levels.
9
Kühnlein, Christian, Andreas Dörnbrack, and Martin Weissmann. "High-Resolution Doppler Lidar Observations of Transient Downslope Flows and Rotors." Monthly Weather Review 141, no. 10 (2013): 3257–72. http://dx.doi.org/10.1175/mwr-d-12-00260.1.
Full textAbstract:
Abstract The authors present observations of the temporal evolution of downslope windstorms with rotors and internal hydraulic jumps of unprecedented detail and spatiotemporal coverage. The observations were carried out by means of a coherent Doppler lidar in the lee of the southern Sierra Nevada range during the sixth intensive observational period of the Terrain-induced Rotor Experiment (T-REX) in 2006. Two representative flow regimes are analyzed and juxtaposed in this paper. The first case shows pulses of high-momentum air that propagate eastward through the valley with an internal hydraulic jump on the leading edge. The region downstream of the transient internal hydraulic jump is characterized by turbulence but no coherent rotor circulation was observed. During the second case, the strongest windstorm of the field campaign T-REX occurred. The observed features of this event resemble the classical notion of a rotor. Altogether, the Doppler lidar observations of both downslope flow events reveal a complex, turbulent flow that is highly transient, intermittent, 3D, and interacts with a significant along-valley flow.
10
Allen, C. B. "Multigrid multiblock hovering rotor solutions." Aeronautical Journal 108, no. 1083 (2004): 255–61. http://dx.doi.org/10.1017/s000192400000511x.
Full textAbstract:
AbstractThe effect of multigrid acceleration implemented within an upwind-biased Euler method for hovering rotor flows is presented. Previous work has considered multigrid convergence for structured single block rotor solutions. However, for forward flight simulation a multiblock approach is essential and, hence, the flow-solver has been extended to include multigrid acceleration within a multiblock solver. The requirement to capture the vortical wake development over several turns means a long numerical integration time is required for hovering rotors, and the solution (wake) away from the blade is significant. Hence, the solution evolution and convergence is different to a fixed wing case where convergence depends primarily on propagating errors away from the surface as quickly as possible, and multigrid acceleration is shown here to be less effective for hovering rotor flows. Previous single block simulations demonstrated that a simple multigridV-cycle was the most effective, smoothing in the decreasing mesh density direction only, with a relaxed trilinear prolongation operator. This is also shown to be the case for multiblock simulations. Results are presented for multigrid computations with 2, 3, and 4, mesh levels, and a CPU reduction of approximately 80% is demonstrated for 4 mesh levels.
11
Johnston, James P. "Effects of System Rotation on Turbulence Structure: A Review Relevant to Turbomachinery Flows." International Journal of Rotating Machinery 4, no. 2 (1998): 97–112. http://dx.doi.org/10.1155/s1023621x98000098.
Full textAbstract:
Turbomachine rotor flows may be affected by system rotation in various ways. Coriolis and centrifugal forces are responsible for (i) modification of the structure of turbulence in boundary layers and free shear layers, (ii) the generation of secondary flows, and (iii) “buoyancy” currents in cases where density gradients occur. Turbulence modification involves reduction (stabilization) or increase (destabilization) of turbulent Reynolds stresses by Coriolis forces; effects which areof special importance for the understanding and prediction of flows in radial and mixed flow pump and compressor rotors. Stabilization/destabilization effects are discussed by a selective review of the basic research literature on flows in straight, radial, rotating channels and diffusers.
12
Kirtley, K. R., T. A. Beach, and C. Rogo. "Aeroloads and Secondary Flows in a Transonic Mixed-Flow Turbine Stage." Journal of Turbomachinery 115, no. 3 (1993): 590–600. http://dx.doi.org/10.1115/1.2929294.
Full textAbstract:
A numerical simulation of a transonic mixed-flow turbine stage has been carried out using an average passage Navier–Stokes analysis. The mixed-flow turbine stage considered here consists of a transonic nozzle vane and a highly loaded rotor. The simulation was run at the design pressure ratio and is assessed by comparing results with those of an established throughflow design system. The three-dimensional aerodynamic loads are studied as well as the development and migration of secondary flows and their contribution to the total pressure loss. The numerical results indicate that strong passage vortices develop in the nozzle vane, mix out quickly, and have little impact on the rotor flow. The rotor is highly loaded near the leading edge. Within the rotor passage, strong spanwise flows and other secondary flows exist along with the tip leakage vortex. The rotor exit loss distribution is similar in character to that found in radial inflow turbines. The secondary flows and nonuniform work extraction also tend to redistribute a nonuniform inlet total temperature profile significantly by the exit of the stage.
13
Chew, John W., and Nicholas J. Hills. "Computational fluid dynamics for turbomachinery internal air systems." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 365, no. 1859 (2007): 2587–611. http://dx.doi.org/10.1098/rsta.2007.2022.
Full textAbstract:
Considerable progress in development and application of computational fluid dynamics (CFD) for aeroengine internal flow systems has been made in recent years. CFD is regularly used in industry for assessment of air systems, and the performance of CFD for basic axisymmetric rotor/rotor and stator/rotor disc cavities with radial throughflow is largely understood and documented. Incorporation of three-dimensional geometrical features and calculation of unsteady flows are becoming commonplace. Automation of CFD, coupling with thermal models of the solid components, and extension of CFD models to include both air system and main gas path flows are current areas of development. CFD is also being used as a research tool to investigate a number of flow phenomena that are not yet fully understood. These include buoyancy-affected flows in rotating cavities, rim seal flows and mixed air/oil flows. Large eddy simulation has shown considerable promise for the buoyancy-driven flows and its use for air system flows is expected to expand in the future.
14
Dehaeze, F., and G. N. Barakos. "Mesh Deformation Method for Rotor Flows." Journal of Aircraft 49, no. 1 (2012): 82–92. http://dx.doi.org/10.2514/1.c031251.
Full text
15
Zhang, Haoguang, Wenhao Liu, Enhao Wang, Yanhui Wu, and Weidong Yao. "Mechanism investigation of enhancing the stability of an axial flow rotor by blade angle slots." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 13 (2019): 4750–64. http://dx.doi.org/10.1177/0954410019829272.
Full textAbstract:
This paper seeks to reveal the mechanisms of enhancing the stability of a subsonic axial flow rotor by applying blade angle slots casing treatment (BSCT). When blade angle slots are applied, there is about 9% stall margin improvement for the experiment and about 8% stall margin improvement for the calculation, but the decrease in the rotor maximum efficiency is about 11% for the experiment and the calculation. The compared results between smooth wall and blade angle slots indicate that the backflow in the rotor top passage is weakened by the injected and sucked flows formed inside the slots of BSCT. Moreover, the injected flows inside the slots interfere with the flows in the rotor passage upstream, and this interference leads to large flow losses. Therefore, the rotor efficiency for blade angle slots is much lower than that for smooth wall. To confirm that the structural optimization of blade angle slots can effectively improve the compressor stability with small efficiency losses, optimized blade angle slots casing treatment (BSCT1) was designed according to the past experience of slot casing treatment. The calculated result shows that the optimized blade angle slots generate about 59% stall margin improvement, and the compressor maximum efficiency with the optimized blade angle slots is about 0.05% more than that for smooth wall. The flow field analyses show that the strong sucked flows formed inside the slots for BSCT1 can prevent the backflow, which exists in the rotor top passage for BSCT, from appearing. In addition, the level of interference of the flows in the rotor passage upstream for BSCT1 is much lower than that for BSCT, and the corresponding losses with BSCT1 become lower. Therefore, the rotor with BSCT1 has a larger stable operating range and better efficiencies than that with BSCT.
16
Chaisuriyathepkul, Anont, Krisda Suchiva, Pongdhorn Sea-Oui, and Chakrit Sirisinha. "Effect of Mixing Conditions on Phase Morphology of NR/EPDM Blends." Advanced Materials Research 747 (August 2013): 467–70. http://dx.doi.org/10.4028/www.scientific.net/amr.747.467.
Full textAbstract:
A number of mixing parameters including mixing temperature, rotor speed, fill factor, mixing time, and loading sequence have strong influences on mixing quality. In this work, an in-house developed co-rotating batch mixer equipped with the MX2 rotors, which providing a combination of shear and extensional flows, was used to prepare NR/EPDM blends under various mixing temperatures, rotor speeds, and mixing times. Phase morphology and magnitude of coefficient of dispersive mixing (CDM) were used as qualitative and quantitative determination of mixing quality, respectively. It was found that the lower the mixing temperature, the greater the mixing quality would be obtained. The optimum rotor speed was observed at 60 rpm which was probably caused by the counter-balancing effect of shear stress and shear heating.
17
Allen, C. B. "Multigrid acceleration of an upwind Euler method for hovering rotor flows." Aeronautical Journal 105, no. 1051 (2001): 517–24. http://dx.doi.org/10.1017/s0001924000017954.
Full textAbstract:
The effect of multigrid acceleration implemented within an upwind-biased Euler method for hovering rotor flows is presented. The requirement to capture the vortical wake development over several turns means a long numerical integration time is required for hovering rotors, and the solution (wake) away from the blade is significant. Furthermore, the flow in the region near the blade root is effectively incompressible. Hence, the solution evolution and convergence is different to a fixed wing case where convergence depends primarily on propagating errors away from the surface as quickly as possible, and multigrid acceleration is shown to be less effective for hovering rotor flows. It is found that a simple V-cycle is the most effective, smoothing in the decreasing mesh density direction only, with a relaxed trilinear prolongation operator. Results are presented for multigrid computations with 2, 3, 4, and 5 mesh levels, and a CPU reduction of approximately 80% is demonstrated for five mesh levels.
18
Zhang, Hai, Qun Zheng, Guoqiang Yue, and Jie Gao. "Numerical analysis of flows and aerodynamic forces in honeycomb and labyrinth seals." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 227, no. 9 (2012): 1965–79. http://dx.doi.org/10.1177/0954406212470894.
Full textAbstract:
Rotor dynamics and flow characteristics are computed for a honeycomb seal and a corresponding labyrinth seal. Firstly, rotor dynamic parameters, such as amplitude and frequency of vibration are calculated. Then these parameters are used for unsteady fluid flow computation. Numerical results indicate that the rotor vibration can reduce sealing performance and result in additional aerodynamic force on rotor. Further, the aerodynamic forces tend to reduce the self-excited vibration of rotor, and this effect becomes more apparent with the increase of pressure difference. Vortex in seal cavities is deemed to be the primary cause of the above mentioned results. The differences between the two types of seals are presented in this article. Finally, authors conclude that suitable structure design of honeycomb and labyrinth seals, or their combination can minimize rotor vibration.
19
Jennions, I. K., and J. J. Adamczyk. "Evaluation of the Interaction Losses in a Transonic Turbine HP Rotor/LP Vane Configuration." Journal of Turbomachinery 119, no. 1 (1997): 68–76. http://dx.doi.org/10.1115/1.2841012.
Full textAbstract:
Transonic turbine rotors produce shock waves, wakes, tip leakage flows, and other secondary flows that the downstream stators have to ingest. While the physics of wake ingestion and shock interaction have been studied quite extensively, few ideas for reducing the aerodynamic interaction losses have been forthcoming. This paper aims to extend previously reported work performed by GE Aircraft Engines in this area. It reports on both average-passage (steady) and unsteady three-dimensional numerical simulations of a candidate design to shed light on the interaction loss mechanisms and evaluate the design. The results from these simulations are first shown against test data for a baseline configuration to engender confidence in the numerical approach. Simulations with the proposed newly designed rotor are then performed to show the trade-offs that are being made in such designs. The new rotor does improve the overall efficiency of the group and physical explanations are presented based on examining entropy production.
20
Yamamoto, A. "Production and Development of Secondary Flows and Losses in Two Types of Straight Turbine Cascades: Part 2—A Rotor Case." Journal of Turbomachinery 109, no. 2 (1987): 194–200. http://dx.doi.org/10.1115/1.3262085.
Full textAbstract:
Part 1 of this paper [1] presents the detailed mechanism of secondary flows and the associated losses occurring within a straight stator cascade with a relatively low turning angle of about 65 deg. The significant contribution of secondary flows on the loss production process was shown only near the blade suction surface downstream from the cascade throat (Z/Cax = 0.74) in which regional flows decelerated due to adverse pressure gradient. In the second part, the same experimental analysis is applied to a straight rotor cascade with a much larger turning angle of 102 deg. Flow surveys were made at 12 traverse planes located throughout the rotor cascade. The larger turning results in a similar but much stronger contribution of the secondary flows to the loss developing mechanism. Evolution of overall loss starts quite early within the cascade, and the rate of the loss growth is much larger in the rotor case than in the stator case.
21
Chan, Shining, Yeyu Chen, Fei Xing, and Huoxing Liu. "Effect of Stagger Angle of Rotor Channels on the Wave Rotor." Energies 15, no. 24 (2022): 9455. http://dx.doi.org/10.3390/en15249455.
Full textAbstract:
A wave rotor optimizes the use of energy resources by enhancing thermodynamic cycles, and further optimization of wave rotor geometry is emerging as an attractive research area. Among the geometric features, the stagger angle of channels lacks sufficient study in spite of its important effects. To address this question, this work developed and applied the velocity triangle models to modify the basic geometry of wave rotors for different stagger angles, and investigated the flow fields with two-dimensional numerical methods. Results showed that: (1) different stagger angles worked out similar unsteady pressure wave systems and kept nearly constant compression and expansion ratios of the wave rotor; (2) increased stagger angle made the inlet and outlet flows turn toward the axial direction, which was beneficial to compact and light-weighted integration of the wave rotor to a gas turbine; (3) increased stagger angle made the wave rotor consume more shaft power, but even the maximum shaft power was small. This work revealed a critical mechanism how the velocity variation across an unsteady pressure wave produced rim work in a staggered channel, and made a recommendation to comprehensive optimization of wave rotor geometry for better integration in a gas turbine and acceptable shaft power consumption.
22
Steinhoff, John, and K. Ramachandran. "Free-wake analysis of compressible rotor flows." AIAA Journal 28, no. 3 (1990): 426–31. http://dx.doi.org/10.2514/3.10410.
Full text
23
Venkateswaran, S. "Experimental Study of Casing Boundary Layers in a Multistage Axial Compressor." Journal of Fluids Engineering 113, no. 2 (1991): 240–44. http://dx.doi.org/10.1115/1.2909486.
Full textAbstract:
Measurements of the casing boundary layers were obtained in a four-stage, low speed axial flow compressor, to verify the ‘law of the wall’ applicability to these complex flows. Some of the available shear stress models of the two-dimensional flows have been examined towards the quantitative assessment of skin friction. The shear stress prediction obtained from the Ludwieg-Tillmann relation applied to the streamwise or untwisted profile agreed closely with the measured shear stress by the hot wire. The skin friction was fairly constant for rotor and stator flows and was close to the flat plate values. The boundary layer profiles exhibited a well pronounced semi-logarithmic region with the universal constants of the law of the wall far removed from the standard two dimensional values, especially for rotor flows. Stator flows showed signs of similarity to two dimensional flows.
24
Chuang, H. A., and J. M. Verdon. "A Nonlinear Numerical Simulator for Three-Dimensional Flows Through Vibrating Blade Rows." Journal of Turbomachinery 121, no. 2 (1999): 348–57. http://dx.doi.org/10.1115/1.2841321.
Full textAbstract:
The three-dimensional, multistage, unsteady, turbomachinery analysis, TURBO, has been extended to predict the aeroelastic response of a blade row operating within a cylindrical annular duct. In particular, a blade vibration capability has been incorporated, so that the TURBO analysis can be applied over a solution domain that deforms with a vibratory blade motion. Also, unsteady far-field conditions have been implemented to render the computational inlet and exit boundaries transparent to outgoing unsteady disturbances and to allow for the prescription of incoming aerodynamic excitations. The modified TURBO analysis has been applied to predict unsteady subsonic and transonic flows. The intent is to validate this nonlinear analysis partially for blade flutter applications via numerical results for benchmark unsteady flows, and to demonstrate this analysis for a realistic fan rotor. For these purposes, we have considered unsteady subsonic flows through a three-dimensional version of the 10th Standard Cascade and unsteady transonic flows through the first-stage rotor of the NASA Lewis Rotor 67 fan. Some general correlations between aeromechanical stabilities and fan operating characteristics will be presented.
25
Pullan, Graham. "Secondary Flows and Loss Caused by Blade Row Interaction in a Turbine Stage." Journal of Turbomachinery 128, no. 3 (2004): 484–91. http://dx.doi.org/10.1115/1.2182001.
Full textAbstract:
A study of the three-dimensional stator-rotor interaction in a turbine stage is presented. Experimental data reveal vortices downstream of the rotor which are stationary in the absolute frame—indicating that they are caused by the stator exit flowfield. Evidence of the rotor hub passage vortices is seen, but additional vortical structures away from the endwalls, which would not be present if the rotor were tested in isolation, are also identified. An unsteady computation of the rotor row is performed using the measured stator exit flowfield as the inlet boundary condition. The strength and location of the vortices at rotor exit are predicted. A formation mechanism is proposed whereby stator wake fluid with steep spanwise gradients of absolute total pressure is responsible for all but one of the rotor exit vortices. This mechanism is then verified computationally using a passive-scalar tracking technique. The predicted loss generation through the rotor row is then presented and a comparison made with a steady calculation where the inlet flow has been mixed out to pitchwise uniformity. The loss produced in the steady simulation, even allowing for the mixing loss at inlet, is 10% less than that produced in the unsteady simulation. This difference highlights the importance of the time-accurate calculation as a tool of the turbomachine designer.
26
Guo, Z., та D. L. Rhode. "Assessment of Two- and Three-Scale k–ε Models for Rotating Cavity Flows". Journal of Turbomachinery 118, № 4 (1996): 826–34. http://dx.doi.org/10.1115/1.2840940.
Full textAbstract:
A three-scale k–ε turbulence model was recently developed for complex flows such as the rotor–rotor and rotor–stator cavities found in gas turbine engines. The three-scale model is a logical extension of the previous two-scale k–ε model of Ko and Rhode (1990). Both multiscale turbulence models are presented and assessed via comparison with measurements for possible adoption in future cavity computations. A single computer code solving the two-dimensional axisymmetric Navier–Stokes equations with a “switch” for selecting among the various turbulence models being compared was used. It was found for both cavity cases that the three-scale model gives a marginal improvement over the two-scale model. Further, both multiscale models give a substantial improvement over the standard k–ε model for the rotor–stator case, especially in the near-wall region where different eddy sizes are found. However, the feasibility of using a multiscale model for the rotor–rotor case is unclear since it gives improved values over the standard high-Re model in some regions but worse values in other regions. In addition, the solutions provide enhanced insight concerning the large changes in flow pattern previously photographed in the rotor–rotor case as rotation increases. In particular, it is shown how: (a) the number of recirculation zones increase with increasing rotation rate and (b) the recirculation zones decrease in size with a decreasing G ratio.
27
Shaza Rae Selvarajoo, Zulfaa Mohamed-Kassim, and Wei Shyang Chang. "Aerodynamic Characterization of Darrieus Turbines during Self-Start at different Azimuthal Quadrants." CFD Letters 15, no. 2 (2023): 126–42. http://dx.doi.org/10.37934/cfdl.15.2.126142.
Full textAbstract:
One key technology to extract kinetic energy from wind and water is the vertical-axis turbines. However, these flows and currents often fluctuate, forcing the turbine rotors to operate in transient modes. To improve rotor performance, the transient aerodynamic characteristics across the four quadrants of the rotor sweep must be well-understood. We address this need by simulating the transient process of a 3-bladed Darrieus turbine rotor during self-start using the dedicated turbine aerodynamics software QBlade. The simulated transient evolution of the rotor compares well against the experimental and computational-fluid-dynamics data from previous studies. When the rotor self-starts within its first three cycles, its torque is contributed differently from each of the four quadrants. Respectively, its windward and upwind quadrant positively contributes by up to 43% and 326% each to the overall torque, and the leeward and downwind quadrant negatively reduces by up to -346% and -85% each from the overall torque. However, upon reaching steady state, these roles change where the positive torques are contributed by the upwind and leeward quadrants by up to 120% and 10%, respectively, while the negative torques are caused by the downwind and windward quadrants by up to -18% and -13%, respectively. Insights into these rotor dynamics can be later used to propose newer rotor designs or operations to improve the transient performance of the turbine
28
Sydney, Anish, and J. Gordon Leishman. "Time-Resolved Measurements of Rotor-Induced Particle Flows Produced by a Hovering Rotor." Journal of the American Helicopter Society 59, no. 2 (2014): 1–16. http://dx.doi.org/10.4050/jahs.59.022004.
Full text
29
Bai, Xing-Zhi, Zhe Zhang, Wen-Hua Wu, et al. "Fluid Dynamics of Interacting Rotor Wake with a Water Surface." Drones 8, no. 9 (2024): 469. http://dx.doi.org/10.3390/drones8090469.
Full textAbstract:
Rotor-type cross-media vehicles always induce considerably complex mixed air–water flows when approaching the water surface, resulting in relative thrust loss and structural damage on rotor. The interactions between a water surface and rotor wake bring potential risks to the cross-media process, which is known as the near-water effect of the rotor. In this paper, experimental investigations are used to explore the fluid dynamics of the near-water effect of the rotor. Qualitative droplet observation was carried out on the 0.25 m and 0.56 m diameter commercial rotor blades and the 0.07 m diameter ducted fan near the water surface first to gain a qualitative understanding of droplet characteristics. The results show that the rotor wake caused water surface deformation, droplet tearing off, splashing, and entrainment into the rotor disk. The depression formed by the rotor downwash flow impacting the water surface is named as three modes: dimpling, splashing, and penetrating, and the correlation between the depression modes and the aerodynamic characteristics of the rotor is primary analyzed. The flow mechanisms of dimpling mode were studied using the particle image velocimetry (PIV) technique. The results showed that the cavity and liquid crown obviously alter the flow direction of water surface jets, but not all rotors near water enter the vortex ring state. Two splashing mechanisms were revealed, including the direct ejection of droplets at the rim of depression and the tearing of liquid crown by the water surface jets. The blade tip vortex in the surface jet is a potential cause of entrainment into the rotor disk and secondary breakup of the droplet.
30
Cîrciu, Ionică, Doru Luculescu, Vasile Prisacariu, Eduard Mihai, and Constantin Rotaru. "Theoretical Analysis and Experimental Researches regarding the Asymmetrical Fluid Flow Applied in Aeronautics." Advances in Materials Science and Engineering 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/681284.
Full textAbstract:
The current paper has been written in order to find the best solutions to replace the antitorque rotor of single-rotor helicopters, with removal of its disadvantages through the Coandă Effect. This would significantly increase the flight performance. The research mainly aims at obtaining a controlled lateral force due to Coandă flows through the tail boom, a force which would be useful for the stabilization needed because of the lifting rotor during the flight of single-rotor helicopters.
31
Vogel, C. R., and R. H. J. Willden. "Designing multi-rotor tidal turbine fences." International Marine Energy Journal 1, no. 1 (Aug) (2018): 61–70. http://dx.doi.org/10.36688/imej.1.61-70.
Full textAbstract:
An embedded Reynolds-Averaged Navier-Stokes blade element actuator disk model is used to investigate the hydrodynamic design of tidal turbines and their performance in a closely spaced cross-stream fence. Turbines designed for confined flows are found to require a larger blade solidity ratio than current turbine design practices imply in order to maximise power. Generally, maximum power can be increased by operating turbines in more confined flows than they were designed for, although this also requires the turbines to operate at a higher rotational speed, which may increase the likelihood of cavitation inception. In-array turbine performance differs from that predicted from single turbine analyses, with cross-fence variation in power and thrust developing between the inboard and outboard turbines. As turbine thrust increases the cross-fence variation increases, as the interference effects between adjacent turbines strengthen as turbine thrust increases, but it is observed that cross-stream variation can be mitigated through strategies such as pitch-to-feather power control. It was found that overall fence performance was maximised by using turbines designed for moderately constrained (blocked) flows, with greater blockage than that based solely on fence geometry, but lower blockage than that based solely on the turbine and local flow passage geometry to balance the multi-scale flow phenomena around tidal fences.
32
Bazilevs, Y., A. Korobenko, J. Yan, A. Pal, S. M. I. Gohari, and S. Sarkar. "ALE–VMS formulation for stratified turbulent incompressible flows with applications." Mathematical Models and Methods in Applied Sciences 25, no. 12 (2015): 2349–75. http://dx.doi.org/10.1142/s0218202515400114.
Full textAbstract:
A numerical formulation for incompressible flows with stable stratification is developed using the framework of variational multiscale methods. In the proposed formulation, both density and temperature stratification are handled in a unified manner. The formulation is augmented with weakly-enforced essential boundary conditions and is suitable for applications involving moving domains, such as fluid–structure interaction. The methodology is tested using three numerical examples ranging from flow-physics benchmarks to a simulation of a full-scale offshore wind-turbine rotor spinning inside an atmospheric boundary layer. Good agreement is achieved with experimental and computational results reported by other researchers. The wind-turbine rotor simulation shows that flow stratification has a strong influence on the dynamic rotor thrust and torque loads.
33
Wang, X., C. Xie, W. Zhang, and G. Q. Q. G. Meng. "Influence of Rotor Geometry on Cavitation Characteristics of Rotational Hydrodynamic Cavitation Generator." IOP Conference Series: Earth and Environmental Science 1037, no. 1 (2022): 012025. http://dx.doi.org/10.1088/1755-1315/1037/1/012025.
Full textAbstract:
Abstract The RNG k-ε turbulence model and mass transport cavitation model are applied to simulate the cavitating flows in a rotational hydrodynamic cavitation generator with a rotor and a stator. The cavitation generator is designed to have surface dimples on the rotor. The cavitating flows analyses in cavitation generator are focused mainly in the rotor. The accuracy and reliability of the calculation model and method are demonstrated by the good agreement between with experimental and numerical results. The pressure distribution, streamline distribution and vapor volume fraction distribution in cavitation generator with five different structures (5 different diameter of rotor dimples d=11mm, 13mm, 15mm, 17mm, 19mm) under the same operation condition are analysed. The calculation results show that the characteristics of streamline and cavitaion area and pressure area are quite different based on the magnitude of the dimple diameter of the rotor. It is observed that with the rotor dimple diameter increase, the cavity bubbles firstly appear in the low pressures area of dimple bottom and develops rapidly towards the wall and top of dimple; the mass transfer between water and vapor is even more intense; the low pressures area increases in dimple and the vortex area expands and the number of vortices increases, which induces the strong turbulence on the surface of the rotor and inside the rotor. The increasing the diameter of the rotor dimple is an effective means to enhance the cavitation effect of the rotational hydrodynamic cavitation generator.
34
Billy, Frédéric, Mihai Arghir, and Gérard Pineau. "Navier–Stokes Analysis of a Regular Two-Dimensional Roughness Pattern Under Turbulent Flow Regime." Journal of Tribology 128, no. 1 (2005): 122–30. http://dx.doi.org/10.1115/1.2000271.
Full textAbstract:
The present work deals with the flow characteristics induced by a two-dimensional textured surface. The texture consists of identical and equally spaced rectangles with characteristic lengths at least one order of magnitude larger than the clearance of the thin film. Periodic boundary conditions enable the analysis of a single groove and the complete Navier–Stokes analysis is carried on for turbulent flow Reynolds numbers. The analysis is performed for shear driven flows (Couette), pressure driven flows (Poiseuille), and combined Couette–Poiseuille flows. First, the presence of inertial forces generated by the groove is emphasized by the momentum balance performed for the computational cell. The peculiar effect of the groove is also shown by the rotor and the stator shear stresses variations. Finally, it is shown that despite the presence of fluid inertia forces, cell-averaged rotor, and stator shear stresses obtained for pure Couette or Poiseuille flows can be added or subtracted to obtain with good accuracy the characteristics of combined shear and pressure driven flows.
35
Altman, Donald B. "Critical layers in accelerating two-layer flows." Journal of Fluid Mechanics 197 (December 1988): 429–51. http://dx.doi.org/10.1017/s0022112088003313.
Full textAbstract:
A series of laboratory experiments on accelerating two-layer shear flows over topography is described. The mean flow reverses at the interface of the layers, forcing a critical layer to occur there. It is found that for a sufficiently thin interface, a slowly growing recirculating region, the ‘acceleration rotor’, develops on the interfacial wave at mean-flow Richardson numbers of O(0.5). This, in turn, can induce a secondary dynamical shear instability on the trailing edge of the wave. A single-mode, linear, two-layer numerical model reproduces many features of the acceleration rotor if mean-flow acceleration and bottom forcing are included. Velocity measurements are obtained from photographs using image processing software developed for the automated reading of particle-streak photographs. Typical results are shown.
36
Valarezo, Walter O. "Surface panel method for installed multiple rotor flows." Journal of Aircraft 28, no. 8 (1991): 496–501. http://dx.doi.org/10.2514/3.46054.
Full text
37
Cheah, S. C., H. Iacovides, D. C. Jackson, H. Ji, and B. E. Launder. "Experimental investigation of enclosed rotor-stator disk flows." Experimental Thermal and Fluid Science 9, no. 4 (1994): 445–55. http://dx.doi.org/10.1016/0894-1777(94)90022-1.
Full text
38
Ji, Hong-Keun, and Jae-Yong Song. "Study on the Fire Risk in Locked-Rotor Condition of Single-Phase Induction Motor." Fire Science and Engineering 34, no. 2 (2020): 64–71. http://dx.doi.org/10.7731/kifse.78b50c46.
Full textAbstract:
In this paper, the fire risk of a single-phase induction motor under a locked-rotor condition is described. In general, motor failure occurs in the locked-rotor condition owing to poor rotation of the rotor. Large inrush current flows when a motor starts, which is approximately 2–15 times larger than the rated current. In a single-phase induction motor under the locked-rotor condition, a large current that corresponds to the inrush current flows continuously through the stator winding. Such an overcurrent rises the temperature inside the stator winding, and thus the insulating material may catch fire. In this study, the restrained operating condition of the single-phase induction motor was simulated. Further, the degree of the overcurrent and temperature rise in the stator winding was measured. The experimental results, confirmed that the overcurrent was seven times larger than the rated current and the fire commenced at a temperature of approximately 300 ℃ inside the stator winding.
39
Vasiliev, V. I. "On the Prediction of Axisymmetric Rotating Flows by a One-Equation Turbulence Model." Journal of Fluids Engineering 122, no. 2 (2000): 264–72. http://dx.doi.org/10.1115/1.483254.
Full textAbstract:
A one-equation model previously tested for parabolic flows and 2-D separated flows was implemented for rotating flows. Flows in rotor-stator disk systems, and in sealed cavities between contrarotating and corotating disks, were calculated and compared with known experimental and numerical data. For buoyancy-driven flow in a rotating cavity, an analytic solution for the turbulent regime was obtained. [S0098-2202(00)01302-X]
40
Mehrabi, Ali, and Ali Reza Davari. "Experimental Investigation of Impacting Flow between a Sub-Scale Twin-Rotor Configuration." International Journal of Engineering and Technology Innovation 10, no. 3 (2020): 211–24. http://dx.doi.org/10.46604/ijeti.2020.4933.
Full textAbstract:
In this paper, a series of experiments have been performed to understand the semi-quiescent and the impacting flow structure beneath the twin-rotor configuration body using a multipurpose test stand with a sub-scale model airframe in the ground effects. So, the main purpose was to perform a qualitative investigation on the recirculated impacting flow between the twin-rotors. Pressure and velocity measurements were performed by the pressure ports embedded longitudinally along the airframe. The results show that for a single rotor an impinging jet-like small region and rearward and upward flows were below the body. The presence of the second rotor in configurations causes an impacting flow formation in the longitudinal center region below the airframe and a semi-quiescent flow formed there. The positive effects of this flow includes increasing the sub-body pressure and lifting force, the pressure distribution balance, and desirable pressure gradient on sidewalls of the airframe. Tuft tests observations confirm that the location of the impacting flow formation is affected by the pressure and velocity measurements. The mentioned impacting flow aerodynamic effects must be taken into account in design of the flight controls trims and stability systems of twin-rotor configurations.
41
Smith, Natalie R., and Nicole L. Key. "Vane Clocking Effects on Stator Suction Side Boundary Layers in a Multistage Compressor." International Journal of Rotating Machinery 2016 (2016): 1–14. http://dx.doi.org/10.1155/2016/5921463.
Full textAbstract:
The stator inlet flow field in a multistage compressor varies in the pitchwise direction due to upstream vane wakes and how those wakes interact with the upstream rotor tip leakage flows. If successive vane rows have the same count, then vane clocking can be used to position the downstream vane in the optimum circumferential position for minimum vane loss. This paper explores vane clocking effects on the suction side vane boundary layer development by measuring the quasi-wall shear stress on the downstream vane at three spanwise locations. Comparisons between the boundary layer transition on Stator 1 and Stator 2 are made to emphasize the impact of rotor-rotor interactions which are not present for Stator 1 and yet contribute significantly to transition on Stator 2. Vane clocking can move the boundary layer transition in the path between the wakes by up to 24% of the suction side length at midspan by altering the influence of the Rotor 1 wakes in the 3/rev modulation from rotor-rotor interactions. The boundary layer near the vane hub and tip experiences earlier transition and separation due to interactions with the secondary flows along the shrouded endwalls. Flow visualization and Stator 2 wakes support the shear stress results.
42
Wang, Zhiyuan, Can Kang, Yongchao Zhang, Hyoung-Bum Kim, and Feng Jin. "Effect of blade chord length on startup performance of H-type tidal current turbine rotor." AIP Advances 13, no. 3 (2023): 035131. http://dx.doi.org/10.1063/5.0141151.
Full textAbstract:
This study aims to reveal the effect of the blade chord length on the startup performance of the lift rotor that converts the kinetic energy of tidal currents. The computational fluid dynamics technique was used to simulate unsteady flows around the rotor. The six degrees of freedom method was adopted to model the correlation between the rotational speed of the rotor and influential torques acting on the rotor. A comparative analysis of transient flows, rotational speed, and output torque was implemented at different initial azimuthal angles. The results show that as the rotor starts up at the minimum torque, the time required to attain the maximum rotational speed is longer than that associated with the maximum torque. As the maximum rotational speed is reached, low-pressure elements are produced in the area enclosed by the rotor blades, which is insensitive to the initial setting angle. A large area of low pressure is responsible for low output torque. During the startup process, the rotational speed experiences stages of sharp increase, fluctuating decrease, and moderate fluctuation, as is common at different blade chord lengths. As the chord length increases from 0.16 to 0.24 m, the startup process is extended by 0.63 s, and the average rotational speed in the stabilization stage decreases.
43
Strazisar, A. J. "Investigation of Flow Phenomena in a Transonic Fan Rotor Using Laser Anemometry." Journal of Engineering for Gas Turbines and Power 107, no. 2 (1985): 427–35. http://dx.doi.org/10.1115/1.3239743.
Full textAbstract:
Several flow phenomena, including flow field periodicity, rotor shock oscillation, and rotor shock system geometry have been investigated in a transonic low aspect ratio fan rotor using laser anemometry. Flow periodicity is found to increase with increasing rotor pressure rise and to correlate with blade geometry variations. Analysis of time-accurate laser anemometer data indicates that the rotor shock oscillates about its mean location with an amplitude of 3–4 percent of rotor chord. The shock surface is nearly two-dimensional for levels of rotor pressure rise at and above the peak efficiency level but becomes more complex for lower levels of pressure rise. Spanwise shock lean generates radial flows due to streamline deflection in the hub-to-shroud streamsurface.
44
Hebert, G. J., and W. G. Tiederman. "Comparison of Steady and Unsteady Secondary Flows in a Turbine Stator Cascade." Journal of Turbomachinery 112, no. 4 (1990): 625–32. http://dx.doi.org/10.1115/1.2927703.
Full textAbstract:
The effect of periodic rotor wakes on the secondary flow structure in a turbine stator cascade was investigated. A mechanism simulated the wakes shed from rotor blades by passing cylindrical rods across the inlet to a linear cascade installed in a recirculating water flow loop. Velocity measurements showed a passage vortex, similar to that seen in steady flow, during the time associated with undisturbed fluid. However, as the rotor wake passed through the blade row, a large crossflow toward the suction surface was observed in the midspan region. This caused the development of two large areas of circulation between the midspan and endwall regions, significantly distorting and weakening the passage vortices.
45
Hall, E. J. "Aerodynamic modelling of multistage compressor flow fields Part 1: Analysis of rotor-stator-rotor aerodynamic interaction." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 212, no. 2 (1998): 77–89. http://dx.doi.org/10.1243/0954410981532153.
Full textAbstract:
The primary purpose of this study was to investigate improved numerical techniques for predicting flows through multistage compressors. The vehicle chosen for this study was the Pennsylvania State University Research Compressor (PSRC). The PSRC facility consists of a 3 1/2-stage axial flow compressor which shares design features which are consistent with embedded stages of modern gas turbine engine axial flow compressors. In Part 1 of this two-part paper, several computational fluid dynamics techniques were applied to predict both steady and unsteady flows through the PSRC facility. Interblade row coupling via a circumferentially averaged mixing-plane approach was employed for steady flow analysis. A mesh density sensitivity study was performed to define the minimum mesh requirements necessary to achieve reasonable agreement with the experimental data. Time-dependent flow predictions were performed using a time-dependent interblade row coupling technique. These calculations evaluated the aerodynamic interactions occurring between rotor 2, stator 2 and rotor 3 for the PSRC rig.
46
Ma, Jingyuan, and Feng Lin. "Loss Analysis of a Transonic Rotor with a Differential Approach to Entropy Generation." Machines 11, no. 4 (2023): 472. http://dx.doi.org/10.3390/machines11040472.
Full textAbstract:
The loss mechanism of transonic axial compressors is a long-standing problem that involves almost all types of entropy generation in fluid flows, such as skin friction, shock waves, shear flows, corner separation, and tip vortices. Primarily, sources need to be identified and quantitative comparisons of their contributions need to be made. For such determination, we propose herein a differential approach to entropy generation, called the “differential approach”. Two case studies are analyzed to determine the applicability of this approach: (1) laminar and turbulent incompressible flows in straight circular ducts and (2) turbulent compressible flows in convergent-and-divergent nozzles with shock waves. The results lead to the following conclusions: (a) Qualitatively, the differential approach works well, and the quantified measure is reliable if it is calculated with quality meshes and a suitable turbulence model. This means that the differential approach can be a good tool for predesign optimization. (b) When shocks occur within flow fields, the shock-induced boundary-layer separation can generate more loss than the shock loss alone. Subsequently, the differential approach is applied to complex flows in the NASA Rotor 67, which is a well-known bench-test transonic rotor. The results show that the differential approach not only determines the local losses and associates the source of losses with the flow structures but also qualitatively compares and identifies the largest contributors. These results provide a theoretical foundation for optimizing rotor design and enhancing stability.
47
Merala, Raymond, Mont Hubbard, and Takashi Miyano. "Modeling and Simulation of a Supercharger." Journal of Dynamic Systems, Measurement, and Control 110, no. 3 (1988): 316–23. http://dx.doi.org/10.1115/1.3152688.
Full textAbstract:
A dynamic model is developed for simulating and predicting performance for superchargers of relatively arbitrary geometric configuration. A thermodynamic control volume approach and bond graph models are used to derive continuity and energy equations linking the various control volumes. Bond graphs also serve to study and understand the causal implications of laws governing flows between control volumes and system dynamics. Heat transfer is neglected. Simulation outputs include time histories of pressure, temperature, mass, and energy associated with each control volume, time histories of the various flows in the supercharger, and overall volumetric efficiency. Volumetric efficiencies are predicted over a wide range of speed/pressure ratio combinations and are within three percent of experimentally measured values. The simulation is used to investigate the sensitivity of supercharger performance to several key design parameters, including rotor-rotor separation, and rotor-housing and side plate clearance distances.
48
Laskin, A. A., R. R. Yakupov, A. A. Raykov, T. N. Mustafin, S. I. Salikeev, and A. V. Burmistrov. "Mathematical Model of Screw Vacuum Pump Working Process." Proceedings of Higher Educational Institutions. Маchine Building, no. 8 (749) (August 2022): 65–73. http://dx.doi.org/10.18698/0536-1044-2022-8-65-73.
Full textAbstract:
The screw vacuum pump combines high performance, low ultimate pressure and ability to create an oil-free vacuum. The calculation of the pump characteristics can be performed using mathematical modeling. The article considers main stages of creating a mathematical model: constructing the geometry of the rotors, calculating the dependence of the working cavity volume and the area of the suction and discharge windows on the angle of rotor rotation, determining the main directions of gas flows, calculating the dependence of pressure and temperature on the angle of rotor rotation. The thermodynamic model of the working process is based on gas state differential equations describing the laws of mass and energy conservation in control volumes, taking account of heat transfer and overflows. The classification of slotted channels in a screw pump is given, and a method for calculating gas backflows through them is proposed. The calculated dependences of the speed of action on the inlet pressure for various rotor speeds are presented. The developed model can be used for calculating the pumping characteristics of a screw vacuum pump at the design stage.
49
Barakos, G. N., and A. Jimenez Garcia. "CFD analysis of hover performance of rotors at full- and model-scale conditions." Aeronautical Journal 120, no. 1231 (2016): 1386–424. http://dx.doi.org/10.1017/aer.2016.58.
Full textAbstract:
ABSTRACTAnalysis of the performance of a 1/4.71 model-scale and full-scale Sikorsky S-76 main rotor in hover is presented using the multi-block computational fluid dynamics (CFD) solver of Glasgow University. For the model-scale blade, three different tip shapes were compared for a range of collective pitch and tip Mach numbers. It was found that the anhedral tip provided the highest Figure of Merit. Rigid and elastic full-scale S-76 rotor blades were investigated using a loosely coupled CFD/Computational Structural Dynamics (CSD) method. Results showed that aeroelastic effects were more significant for high thrust cases. Finally, an acoustic study was performed in the tip-path-plane of both rotors, showing good agreement in the thickness and loading noise with the theory. For the anhedral tip of the model-scale blade, a reduction of 5% of the noise level was predicted. The overall good agreement with the theory and experimental data demonstrated the capability of the present CFD method to predict rotor flows accurately.
50
Blair, M. F. "An Experimental Study Heat Transfer in a Large-Scale Turbine Rotor Passage." Journal of Turbomachinery 116, no. 1 (1994): 1–13. http://dx.doi.org/10.1115/1.2928273.
Full textAbstract:
An experimental study of the heat transfer distribution in a turbine rotor passage was conducted in a large-scale, ambient temperature, rotating turbine model. Heat transfer was measured for both the full-span suction and pressure surfaces of the airfoil and for the hub endwall surface. The objective of this program was to document the effects of flow three dimensionality on the heat transfer in a rotating blade row (versus a stationary cascade). Of particular interest were the effects of the hub and tip secondary flows, tip leakage, and the leading-edge horseshoe vortex system. The effect of surface roughness on the passage heat transfer was also investigated. Midspan results are compared with both smooth-wall and rough-wall finite-difference two-dimensional heat transfer predictions. Contour maps of Stanton number for both the rotor airfoil and endwall surfaces revealed numerous regions of high heat transfer produced by the three-dimensional flows within the rotor passage. Of particular importance are regions of local enhancement (as much as 100 percent over midspan values) produced on the airfoil suction surface by the secondary flows and tip-leakage vortices and on the hub endwall by the leading edge horseshoe vortex system.