Lift Phenomenon Research Articles

18O isotopic labelling and soil water content fluctuations validate the hydraulic lift phenomena for C3 grass species in drought conditions

Hydraulic lift is a functional characteristic observed in some plant species, often associated with their ability to withstand drought conditions. It involves capturing water from deep soil layers and redistributing it to shallower soil layers through the plant's roots. Bromus valdivianus Phil., Dactylis glomerata L., and Lolium perenne L. may perform hydraulic lift at varying rates. Using both direct (isotopic labelling - δ18O) and indirect (soil water content sensors) techniques, the study assessed and validated the hydraulic lift under extreme drought conditions on the soil top layer (below permanent wilting point), maintaining the bottom layer at high (20–25% filed capacity [FC]) and low (80–85% FC) levels of soil water restriction. Above- and below-ground biomass growth and morpho-physiological responses were evaluated. All species displayed some degree of hydraulic lift, with significant differences observed in the isotopic analysis and soil water content (p > 0.05). This illustrates that water was redistributed from the deep to shallower soil layer and validates that the hydraulic lift phenomenon is occurring in these C3 grasses. Bromus valdivianus presented the highest δ18O values (25.05‰) and highest increases in soil water content (µ=0.00626 m3 m−3; five events). Bromus valdivianus had a dry matter ratio of approximately 4:1 (0–20cm:20–40 cm). In contrast, L. perenne and D. glomerata had approximately 6:1 and 5:1, respectively. This difference in root morphology may explain the higher rate of hydraulic lift observed in B. valdivianus relative to L. perenne and D. glomerata. This paper validates the occurrence and provides initial insights into the hydraulic lift process occurrence of temperature grass species.

Capillary rise behavior of lubricant in micropores with spiral bulge structures.

The highly efficient exudation of lubricant in porous self-lubricating materials significantly influences the formation of self-lubricating films. In this paper, micropores with inner spiral bulge structures are considered, and their influence on the capillary behaviors of the lubricant is discussed to reveal the capillary rising mechanism. The results show that the Taylor capillary lift phenomenon is produced in the spiral bulge structure of the micropore, and the capillary lift force is enhanced. The spiral structure decreases the effective diameter of micropores. The magnitudes of the pressure and velocity in the spiral structure pores are larger than those in smooth pores. The liquid in the upper part of the micropores forms a velocity vortex during its upward rotation along the spiral channel, which promotes the capillary rising behavior. For smaller pitches, the velocity vortex increases, and the rising speed of the lubricant grows. The inner spiral bulge structure gives the micropores an excellent capillary rising ability. The quantitative characterization and mechanism reveal that the capillary rising behavior can be used to guide the bionic designs of pores in self-lubricating materials.

Opportunities for the implementation of career lift technology in higher educational institutions

Introduction. The article is devoted to the involvement of higher education stakeholders in the process of building students and graduates’ careers. The purpose of the article is to summarize modern ideas about the phenomenon of ‘a career lift’ and present author's views on the possibilities of implementing a career lift technology in higher educational institutions. Materials and Methods. The paper presents a subject-centered conceptual model of implementing the career lift technology, based on the methodology of systemic, subject-activity and environmental approaches to scientific cognition. The research methods included etymological and bibliographic analysis used to summarize and clarify the concepts of ‘career’ and ‘career lift’. The modeling method was employed for the complex study and reproduction of the structure and the properties of the career lift technology in universities. Results. The author presented an analysis of existing world approaches to the interpretation of the concept of ‘career’, summarized their main features and presented a clarified definition of this phenomenon. Based on the etymological and bibliographic analysis of the concepts ‘career’, ‘lift’ and ‘career lift’, reflected in dictionaries and scholarly literature (both Russian and international), the author proposed and justified her approach interpreting the career lift phenomenon. As a result, the author proposed two ways of interpreting the concept of the career lift. According to the first one, a career lift is a type of career building chosen by a person. The second one considers career lift as a technology of career support for students, graduates, and professionals. Based on the analysis and personal experience, the author developed and justified a subject-centered model of the career lift technology, implemented in several stages related to individual goals of a person as a subject of education. It is important to note that the model contains links between student's goals and goals and activities of higher education institutions and other stakeholders. The author argues that all the components of each level relatively exist as independent, since they always act interconnected with each other. Conclusions. The author concludes that the subject-centered implementation of the career lift technology, based on the principles of consistency, flexibility, individual and environmental determination, and multidimensionality, is designed to ensure the effectiveness of actions and interactions within its structure.

Study on Triggering Characteristics and Induced Breakdown Rules of SF₆ Gap Switch Plasma Jets at Extremely Low Working Voltage

The SF₆ gap switch has obvious advantages in the flexible control very fast switch of the controllable arrester used in hybrid UHVDC system. However, the plasma jet ability in SF₆ atmosphere at high pressure is greatly restricted, which is easy to cause trigger failure. The triggering characteristics and induced breakdown mechanism are still unclear during the plasma jet-triggered process of the SF₆ gap switch at extremely low working voltage. In this study, a plasma jet-induced breakdown research platform based on two-stage continuous surface-triggered gas gap switch (GGS) was established to investigate time-space distribution evolution characteristics, the critical triggering conditions parameters, and working voltage functioning rules of the SF₆ gap. The jet plasma has a high-brightness-like conical shape, and its initial jet velocity can reach more than 2 km/s. Increasing capacitance value and charging voltage of the secondary chamber in SF₆ gap switch trigger cavity, its creeping arc current is increased, and the time delay and dispersion will be reduced. Moreover, the geometric characteristics (including jet area, jet radial and axial length, and jet velocity) and electrical parameters of the jet plasma increase gradually. Increasing the working voltage of main gap in SF₆ gap switch, the plasma jet velocity lift phenomenon appears at induced breakdown end of SF₆ gap switch. With the continuous increase of the working voltage, the lift effect is more significant. The purpose of this study is to solve the key problem of plasma-induced breakdown failure of the SF₆ gap switch, which will guide the design of fast self-recovery energy discharge protection switches for hybrid UHVDC transmission systems.

INTERCHANGEABILITY AND STANDARDIZATION OF THE PARAMETERS OF COMBUSTIBLE GASES WHEN USING HYDROGEN

Introduction and purpose of the study: The paper presents results of studies aimed to provide a rationale for the possibility of a gradual transition to hydrogen combustion in gas supply to domestic and commercial consumers without changes in the design and operation of burners. For this purpose, we have considered tasks of determining the indicators of interchangeability for natural gas and its mixtures with hydrogen. The main characteristics of combustible gases with various hydrogen content in a mixture have been studied. We have established the impact of the hydrogen content on the heat rate, emissions of harmful substances, as well as light back and flame lift phenomena. We have also analyzed the available interchangeability criteria and their applicability when using natural gas/hydrogen mixtures. The impact of the hydrogen content on the radiation heat transfer in the furnaces of gas equipment is described in the paper for the first time. Methods: The methodology of the paper is based on a critical analysis of available literature data on combustible gases interchangeability as well as theoretical and experimental studies performed by the authors. We have derived dependencies that allow us to determine the possibility of gas equipment transition to the combustion of natural gas/hydrogen mixtures. We have also developed recommendations on the permissible hydrogen content in a natural gas/ hydrogen mixture that would ensure the efficient, safe, and green use of such fuel in domestic and commercial heating units. Results: Scientific findings and practical results of the study make it possible to implement partial gradual costeffective decarbonization in the area of gas fuel utilization as an intermediate stage of transition to more extended hydrogen combustion.

Phase-A design of a reusable re-entry vehicle

In this paper, a design procedure developed to obtain a Phase-A compliant optimal aeroshape is presented. The proposed vehicle performs a low Earth orbit re-entry and a landing on a horizontal runway. A conceptual aeroshape design obtained by a multi-disciplinary, multi-objective optimization is modified by the addition of two functionally independent body flaps to the concept windside to envisage the aeroshape control along both the longitudinal and later-directional axes. Body flaps are also added on the rearward sections of the spacecraft leeside. Aerodynamic analyses are carried out throughout the speed regimes expected during re-entry, to address the feasibility of the vehicle design. Furthermore, CFD computation are specifically performed at very low Mach numbers to address body flaps effects on spacecraft aerodynamics at landing conditions. Flowfield results are also provided, with a particular focus on the vortex lift phenomenon generated by the delta planform shape of the vehicle configuration. Specifically, the flow pattern at landing angle of attack is highlighted to account for safety landing conditions. Finally, a single objective optimization is performed to find the best guidance law allowing a safer re-entry compatible with the assigned operational constraints. In doing this, two kinds of re-entry strategies are compared, namely Shuttle-like and heat-flux tracking profiles.

Can the Stereotype Threat and Lift Phenomenon Be Applicable to a Muscular Endurance Task?

ABSTRACTPurpose. Inducing a negative stereotype toward women usually leads to a decrease in women performance and an increase in men performance. These effects were observed during technical tasks. The purpose of the present study was to investigate the effect of this sex stereotype during a non-technical muscular endurance task. The perception of effort, closely related to endurance performance, was also recorded. Based on the type of task and the mere effort account, we predicted that both men and women in the negative stereotype toward women condition would perform better than participants in the two other groups. Method. Seventy-seven participants (38 women and 39 men) were randomly assigned to a negative stereotype toward women, a nullified-stereotype, or a control condition. Then, they performed a submaximal handgrip task until exhaustion at 50% of their maximal strength. Results. This study showed that performance at T2 was reduced for men and women in the nullified-stereotype and control conditions, but not in the negative stereotype toward women condition, revealing that participants in the negative stereotype toward women condition performed better than participants in the other conditions. No significant difference was observed concerning the perception of effort according to the conditions. Conclusion. As compared to technical tasks, inducing a negative stereotype toward women increased women’s performance. The perception of effort could be responsible for this performance improvement. However, more research is needed to investigate the mechanisms involved. Concerning men, in line with the stereotype lift phenomenon, a performance increase was observed in this same condition.

THE THREE-DIMENSIONAL FLOW SIMULATION OF A FLAPPING WING

This study investigates three-dimensional (3D) flow fields around a flapping wing with a span of 20 cm. Numerical simulations are performed by varying the simulation mesh density for a half-flapping-wing profile with wind tunnel domain for flapping stroke angles of 53° and 90°. Wind velocities ranging from 1 to 3 m/s, variation in flapping frequency of 14-15 Hz, and corresponding lift characteristics are obtained. Comparative evaluation of numerical and experimental lift force data reveals the translational and rotational lift phenomena of Dickinson’s mechanisms. The stream line that flows over the 3D wing profile is found to be in good agreement with the existing smoke trace experimental data. The motions of a flapping wing obtained through 3D stereo photography and COMSOL Multiphysics simulation are compared and the aerodynamic characteristics are exploited. The streamwise and spanwise 3D velocity fields with intercepting planes at three chord sections are explored, and the reverse Karman vortex sheet is observed. The comparison of the simulation and experimental results for a 3D flapping wing provides insight into the motion characteristics of a flapping wing and flapping wing aerodynamic analysis of micro air vehicles.

Effect of leading edge shapes on 81°/45° double-delta wing at low speeds

Investigations were performed on an 81°/45° sweep double-delta wing at a freestream velocity of 20 m/s. Experiments consisted of the measurement of forces, static pressures, and surface flow visualizations. Effect of the leading edge shapes of the double-delta wing was studied. Results indicated a strong influence of the leading edge shape on the aerodynamic performance of the body. The increase in the bluntness of the leading edge augments the suction pressure and delays the vortex lift phenomena at higher angles of attack, which in turn enhances the lift over the wing. A reasonable agreement between the experiments and computations were observed.

Estimation of Shear-Induced Lift Force in Laminar and Turbulent Flows

The goal of the present study is to demonstrate that direct numerical simulations (DNS) coupled with interface tracking methods can be used to estimate interfacial forces in two-phase flows. Current computational multiphase fluid dynamics codes model interfacial forces utilizing closure laws that are heavily dependent on limited experimental data and simplified analytical approximations. In the present work, a method for improving the current interfacial force database has been developed by using DNS to quantify the lift and drag forces on a single bubble in laminar and turbulent shear flows. A proportional-integral-derivative–based controller was implemented into the finite element–based, multiphase flow solver [PHASTA (Parallel, Hierarchic, higher-order accurate, Adaptive, Stabilized, finite element method Transient Analysis)] to control the bubble position. This capability allowed for utilization of a steady-state force balance on the bubble to determine lift and drag coefficients in various shear flows. Specifically, for low shear flows (2.0 s−1), the effect of the wall presence is analyzed, and for high shear flows, the effect of turbulence is studied. A number of uniform shear (10.0 to 470.0 s−1) laminar flows were simulated to assess lift and drag force behavior as the kinetic energy of the flow increased. Two high shear (236.0 and 470.0 s−1) turbulent flows were simulated to understand bubble-turbulence interaction influence on the drag and lift phenomena. Two uniform shear rates (20.0 and 100 s−1) were simulated utilizing pressurized water reactor fluid properties. The lift and drag coefficients estimated in this work are in agreement with models developed for low shear laminar flows, whereas for high shear laminar and turbulent flows, bubble-turbulence interaction became a dominating influence in the lift and drag coefficient estimation. The novel results and method presented in this paper offer a path to simulating full-fledged reactor coolant environments where the lift and drag forces on a single bubble can be studied.

Design, Construction, and Validation of an Internally Lit Air-Lift Photobioreactor for Growing Algae

A novel 28 L photobioreactor for growing algae was developed from a previous bubble column system. The proposed design uses the air lift principle to enhance the culture circulation and induce light/dark cycles to the microorganisms. Optical fibers were used to distribute photons inside the culture media providing an opportunity to control both light cycle and intensity. The fibers were coupled to an artificial light source, however the development of this approach aims for the future use of natural light collected through parabolic solar collectors. This idea could also allow the use of non-clear materials for photobioreactor construction significantly reducing costs and increasing durability. Internal light levels were determined in dry conditions and were maintained above 80 µmol/(s•m2). The hydrodynamic equations of the air lift phenomena were explored and used to define the geometric characteristics of the unit. The reactor was inoculated with the algae strain Chlorella sp. and sparged with air. The reactor was operated under batch mode and daily monitored for biomass concentration. The specific growth rate constant of the novel device was determined to be 0.011 h-1, similar to other reactor designs reported in the literature, suggesting the proposed design can be effectively and economically used in carbon dioxide mitigation technologies and in the production of algal biomass for biofuel and other bioproducts.

Effects of Fuel-Side N2, CO2, H2O Dilution on Combustion Characteristics and NOx Formation of Syngas Turbulent Nonpremixed Jet Flames

The effects of the three fuel-side diluents N2, CO2, and H2O on the accurate flame structure and NOx formation characteristics of the turbulent syngas nonpremixed flames are investigated using the one-dimensional-turbulence (ODT) model. For nonpremixed flames, the fuel mixtures consist of H2, CO and three diluents: N2, H2O, and CO2. The proportion of diluents is varied from 10% to 30% while the H2/CO ratio is kept as a constant at 0.75 all the time. Mass fraction of main species and temperature of 30% N2 basic dilution case predicted by the ODT model are compared with the tests measuring results obtained by International Workshop on Measurements and Computation of Turbulent Nonpremixed Flames, and it is found that the results are in good agreement. Numerical results indicate that the CO2 diluted flames have the largest reduction on flame temperature as well as the NOx emission, while H2O is more effective than N2. For CO2 and H2O dilution flames, flame structure becomes unstable with an obvious lift phenomenon. Since ODT captures the flame extinction process, flames added with CO2 and H2O not only have a lower extinction temperature but also the reignition process is slower.

Numerical analysis for the characteristics of flow control around a circular cylinder with a turbulent boundary layer separation using the electromagnetic force

A detached eddy simulation method with the turbulent separation is presented to simulate and analyze the characteristics for the flow around a circular cylinder with a turbulent boundary layer separation and its lift/drag coefficients in a weakly conductive fluid at a high subcritical Reynolds number 1.4×105 under an electromagnetic force. The results show that the electromagnetic force can increase the fluid kinetic energy near the turbulent boundary layer, delay the turbulent boundary layer separation of the flow around the circular cylinder, and weaken the intensity of the large-scale eddy in the turbulent flow around the circular cylinder in the streamwise and spanwise directions, reduce the time-average drag, and inhibit the lift fluctuation amplitude on the circular cylinder. Moreover, after the electromagnetic force parameter reaches a certain critical value, the turbulent boundary layer separation disappears and the jet phenomenon appears in the wake of the circular cylinder, so that the electromagnetic force produces the thrust action on the circular cylinder and the negative drag occurs, and the lift fluctuation amplitude declines to almost zero and the lift phenomenon on the circular cylinder disappears.

An insight into the separate flow and stall delay for HAWT

The flow characteristics and the stall delay phenomenon of wind turbine rotor due to blade rotation in the steady state non-yawed conditions are investigated. An incompressible Reynolds-averaged Navier–Stokes solver is applied to carry out all the cases at different wind speeds from 5 m/s to 10 m/s with an interval of 1 m/s. CFD results turn out to agree well with experimental ones at incoming wind speeds below 10 m/s, though at 10 m/s some deviations exist due to the relative large flow separation and 3D spanwise flow over the suction surface of the blade. In the meanwhile, a lifting surface code with and without Du–Selig stall delay model is used to predict the power. A MATLAB code is developed to extract aerodynamic force coefficients from 3D CFD computations which are compared with the 2D airfoil wind tunnel experiment to demonstrate the stall delay and augmented lift phenomenon particularly at inboard span locations of the blade. The computational results are compared with the corrected value by the Du–Selig model and a lifting surface method derived data based on the measurements of the Unsteady Aerodynamic Experiment at the NASA Ames wind tunnel.

A parametric study of a thick, incompressible flow over a curved surface

The purpose of this paper is to investigate the lift phenomenon produced by the Coanda effect when a fluid flows over a curved surface. A secondary goal was to quantify and to integrate it on super circulation wing aircraft configurations. Therefore we have conducted a series of CFD studies, varying the fluid velocity and measuring the pressure gradient over the super circulated curved ramp. The results showed that thick jets provide the anticipated lift force which is proportional to the flow velocity. Although in this case the ratio between the Coanda lift and the thrust of the jet itself is less than 10% on average. The immediate interpretation is that, by using thick jets we can increase the lift generated by the SCW aircraft bearing in mind that the main lift is not generated by this effect but rather by diversion of the jet downwards.

Numerical Simulation of Full-Span Delta Wing Buffet at High Angle of Attack

In this work, the buffet of a full-span, highly flexible, 50-deg-sweep delta wing at high angle of attack is studied using a computational aeroelastic solver. The aeroelastic solver couples a second-order finite difference solution of the Euler equations to a large-rotation nonlinear finite element structural solver. Particular attention is paid to the poststall region, in which previous experiments on highly flexible low-sweep delta wings have noted increased buffet response accompanied by lift enhancement and a delay in stall. It is thought that these phenomena are due to the reorganization of the flow and reformation of a leading-edge vortex structure. The nature of this enhanced lift is studied here for the flexible delta wing at an angle of attack of 25 deg and a flow velocity of 30 m/s. Using a prescribed wing motion, it is shown that it is possible to predict lift enhancement by solving only the inviscid Euler equations. The enhanced lift is due to a reorganization of the flow and the resulting region of increased suction near the apex of the wing. It is found that the mode of wing vibration has little influence on the enhanced lift phenomena, because both a prescribed symmetric first-mode motion and a prescribed antisymmetric third-mode motion led to lift enhancement. It is also insensitive to the wing vibration frequency for the range of frequencies tested, with the concession that below some minimum frequency, lift enhancement does not occur. The amplitude of wing vibration has some effect on the time-averaged lift coefficient. Fully coupled aeroelastic computations were also performed in this study for the wing. The fully aeroelastic computation did not predict the enhanced structural dynamic behavior and lift that was observed in the experiment. The dominant dynamic response of the wing was near the first mode, which has a frequency that is too low to initiate flow organization and the resulting enhanced lift due to increased suction.

Analysis of the experimental and computational flow characteristics with respect to the augmented lift phenomenon caused by blade rotation

This article focuses on the augmented lift phenomenon as a result of blade rotation in the steady state non-yawed condition. In the investigations a full Navier Stokes code FLUENT is used instead of engineering models. The calculations are compared with the measurements of the Unsteady Aerodynamic Experiment at the NASA Ames wind tunnel at wind speeds between 8m/s and 15m/s in steps of 1m/s. The computations show good agreement for the pressure distributions for almost all five segments at wind speeds below 10m/s, only large deviations occur at segment r/R= 0.47. Beyond 10m/s deviations with the experiment increase but still, apart from the inboard r/R= 0.30 segment and occasionally the r/R= 0.47 location, the results are surprisingly good. Large separated areas and cross flows dominate the flow on the suction side as can be distracted from the calculated limited streamlines. Integration to the normal force coefficient showed that the trends of the experimental data are followed reasonably well for each span section. The presence of augmented lift and stall delay was confirmed for the span sections at r/R= 0.30 and r/R= 0.47.

Cable Erection Test at Splay Band for Spatial Suspension Bridge

The Yongjong Grand Bridge includes a self-anchored suspension bridge with inclined cable planes. The bridge uses splay bands (cable collars) to flare the main cables at the anchorage, which is located at the end of a stiffening truss. During cable erection, some of the wires at the splay band were expected to experience lateral displacement and/or lift phenomena because of the large flare angles at the splay band. Mockup cable erection tests at the anchorage were carried out to find the degree of displacement of the wires and to determine appropriate measures to deal with these problems. Through these tests, methods to arrange wires at the splay bands were devised and tried, and the selected method was successfully used for the actual bridge.

New Trajectories of the Internet: Umbrellas, Traction, Lift and Other Phenomena.

This article reviews the book New Trajectories of the Internet: Umbrellas, Traction, Lift and Other Phenomena, by Stephen E. Arnold.

MARINE APPLICATION OF MAGNUS EFFECT DEVICES

ABSTRACTThe Magnus effect is an induced, very high lift phenomenon that has been used for wind propulsion of ships as early as 1924. More recently, this unique lift principle has been used for steering towboats. Recent research has indicated that Magnus effect roll stabilizers, water propellers, and air and water generators may be both feasible and have greater efficiency than traditional designs. The paper explains the Magnus effect, reviews the history of the Magnus effect, reviews current marine applications including the work of investigators in Germany, France, Sweden and Russia, discusses in detail Magnus effect rotor design, and proposes auxiliary wind propulsion Magnus effect devices for single screw oilers.