Pump Axis Research Articles

РЕЦИРКУЛЯЦИЯ ЭНЕРГИИ В ГИДРОМЕХАНИЗАЦИИ И НАСОСНОМ ОБОРУДОВАНИИ ВОДОПОДАЮЩИХ НАСОСНЫХ СТАНЦИЙ

The purpose of the study is the theoretical substantiation of the hydraulic method of transferring part of the energy of the pressure line to the suction line in installations of hydromechanization and water transmission systems. The novelty of the work lies in the theoretical substantiation of the influence of the energy of the pressure lines of the hydromechanical equipment of dredging plants and water supply systems on the depth of development of silt deposits and the cavitation reserve of pumping equipment. When designing dredging plants and waterfall systems, it should be borne in mind: 1) the need for operational accounting of both potential and kinetic energy of pressure lines, due to the possible use of free quantities in the suction line, which has a significant impact on the head of the hydromechanical equipment and, accordingly, on the power consumption; 2) during the reconstruction (repair) of existing installations equipped with all types of axial and centrifugal pumps during the installation of pressure and suction pipelines, it is necessary to install additional pipeline fittings in order to facilitate, in case of a drop in the level in the water source, the installation of a recirculation line when transferring part of the energy of the pressure line. The work provides tables for the stepwise transfer of part of the energy into the suction pipeline, showing the degree of deepening of the pump axis relative to the surface of the pumping station building and increasing the length of the suction pipeline of the dredging plant. The necessity of installing a recirculation line for axial pumps in case of an unforeseen drop in the level mark in the water source is justified. The analysis of these examples shows a possible increase in the depth of development of the dredging plant to 30-50 meters and a maximum reduction in the depth of the pumping station building to 40 meters.

Characteristics of Various Losses of Axial Piston Pump and Bent Axis Hydro-motor with respect to Displacement Conditions and Load Demands

The hydrostatic transmission is one of the most important applications in the fluid power systems. It gives smooth change in output speed, torque and power as per the design requirements. Present article deals with various losses of the hydraulic pump and motor using a closed circuit hydraulic drive. The drive basically consists of a variable displacement axial piston pump that supplies pressurized fluid to a variable displacement bent axis hydro-motor. In investigating the pump/motor performance, bond graph simulation technique is used to model the drive system. Various losses of the pump and motor are accounted in the model by suitable resistive elements. The characteristics of them are identified through experiments. The predicted performance of the pump/motor is studied with respect to the displacement and load at the same time they are validated experimentally. The investigation made in the article identifies the control strategy which will be useful for the practicing engineers to select best combination of the pump and motor displacement for optimizing the drive performance and minimizing the losses as well. The study performed in this research work will be useful for the similar hydraulic configuration used in mobile equipment.

Realization of a Periodically Driven Open Three-Level Dicke Model.

A periodically driven open three-level Dicke model is realized by resonantly shaking the pump field in an atom-cavity system. As an unambiguous signature, we demonstrate the emergence of a dynamical phase, in which the atoms periodically localize between the antinodes of the pump lattice, associated with an oscillating net momentum along the pump axis. We observe this dynamical phase through the periodic switching of the relative phase between the pump and cavity fields at a small fraction of the driving frequency, suggesting that it exhibits a time crystalline character.

Octave-spanning supercontinuum generation from off-axis Raman oscillation in a monolithic KTP crystal.

We report generation of a visible and near-infrared supercontinuum from a high-gain, ultra-broadband, and mirrorless Raman oscillator in a monolithic KTP crystal. The plane transverse to the pump axis resonates and traps off-axis Stokes waves and their frequency-upconverted components bouncing between two crystal surfaces via total internal reflection. The Raman gain is maximized with the Stokes polarization perpendicular to the plane of reflections. When pumped by a Q-switched Nd:YAG laser, the monolithic oscillator generates quasi-mode-locked Stokes pulses with octave-spanning spectral groups across the visible and near-infrared spectra between 540 and 1800 nm.

Analysis of vortices formed in flow passage of a five-bladed centrifugal water pump by means of PIV method

Detailed optical measurements for the flow inside rotating passages of a five-bladed centrifugal impeller were performed by particle image velocimetry (PIV). The flow in mid-plane perpendicular to the pump axis was measured at 1400 r/min rotation speed. Seven flow rates, namely, 1.2, 1.0, 0.8, 0.6, 0.4, 0.2, and 0 Qd, were surveyed. The averaged PIV velocity maps and streamline were analyzed. Results show that when flow rate decreases to 0.8 Qd, the flow separation forms initially at the blade suction side in passage 1. With decreasing of flow rate, the flow separation appears in much more passage, the separation region enlarges, and the flow at the pressure side begins to form flow separation. All passages are gradually occupied by the vortices generated by flow separation, until the passages are finally blocked. The scale of vortex along the stream-wise direction at the suction side is larger than that at the pressure side, whereas the scale of vortex along the span-wise direction is smaller than that at the pressure side. With the decrease in flow rate, the scales of vortices at the suction and pressure sides increase, and the vortices at both sides move toward the inlet and outlet, respectively. Moreover, the effect of vortices on the tangential and radial components of the absolute velocity was analyzed.

The preparation of polytrifluorochloroethylene (PCTFE) micro-particles and application on treating bearing steel surfaces to improve the lubrication effect for copper-graphite (Cu/C)

Contact mechanical seal is a normal technology applied on middle axis of liquid rocket turbo pump, and the kinetic and static seal rings contact low temperature rocket propellant. Copper-graphite (Cu/C) composite as an excellent self-lubrication material was widely used in aerospace industry, this study took Cu/C as ball and bearing steel as disk to investigate the tribology properties, and distilled water were used to simulate the lox tribology performances. This study prepared polytrifluorochloroethylene (PCTFE) micro-particles which were coated on the oxide surfaces of bearing steel disk at temperature of 150°C. The tribology results showed that the oxide surfaces treated with micro PCTFE particles have lower fiction coefficient and lower wear rate than original disk in water, and the wear morphology revealed that the treated surfaces obviously had less Cu/C composite transfer film than original disk. Meanwhile SEM, EDS, XRD, XPS and light microscope etc revealed that PCTFE micro-particles could associate with the oxide surfaces and caused higher water contact angle, due to the properties of the fluorine-containing composite may cause the good lubrication effect in water. Thus this technology shows great potential to enhance tribological performances for aerospace industry on a large scale.

集液管及其内部导流板对旋喷泵性能的影响

为研究集液管对旋喷泵性能的影响，本文对旋喷泵内部流场进行了数值模拟，获得了整泵流道内的速度、静压强和湍动能分布。本文对比了不同流量工况下的流动参数分布特征，重点讨论了集液管及内部导流板对流动的影响及集液管受到的流体作用力。结果表明：旋喷泵转子腔内的流动参数分布规律性强，在集液管入口处及集液管内流道转弯处存在着较高的静压强梯度；未设置导流板时集液管内流体湍动能较高，但泵性能较设置导流板时高；集液管所受的流体作用力合力随流量增加而下降，其中沿泵轴的作用力分量占主导地位，加装导流板后集液管的受力略下降。 Numerical simulation was conducted to investigate the influence of the collector on the perfor-mance of a roto-jet pump. Distributions of velocity, static pressure as well as turbulent kinetic energy were obtained thereby. A comparison was implemented on flow parameter distributions at different flow rates. The emphasis was placed upon the effects of the collector and the inner guide vane on flows and the hydraulic forces exerted on the collector. Remarkable flow regularity is ob-served in the rotating chamber. High static pressure gradients occur at the inlet and the turning positions of the collector. Without the guide vane, overall turbulent kinetic energy is high but the pump performance is favorable relative to its counterparts with the guide vane. The resultant hy-draulic force acting upon the collector decreases with the increase of flow rate. The force component along the pump axis is predominant in this connection. A slight reduction of hydraulic force is manifested with the introduction of the guide vane.

Dramatic Raman Gain Suppression in the Vicinity of the Zero Dispersion Point in a Gas-Filled Hollow-Core Photonic Crystal Fiber.

In 1964 Bloembergen and Shen predicted that Raman gain could be suppressed if the rates of phonon creation and annihilation (by inelastic scattering) exactly balance. This is only possible if the momentum required for each process is identical, i.e., phonon coherence waves created by pump-to-Stokes scattering are identical to those annihilated in pump-to-anti-Stokes scattering. In bulk gas cells, this can only be achieved over limited interaction lengths at an oblique angle to the pump axis. Here we report a simple system that provides dramatic Raman gain suppression over long collinear path lengths in hydrogen. It consists of a gas-filled hollow-core photonic crystal fiber whose zero dispersion point is pressure adjusted to lie close to the pump laser wavelength. At a certain precise pressure, stimulated generation of Stokes light in the fundamental mode is completely suppressed, allowing other much weaker phenomena such as spontaneous Raman scattering to be explored at high pump powers.

Background-Free Fourth-Order Sum Frequency Generation Spectroscopy.

The recently developed 2D sum frequency generation spectroscopy offers new possibilities to analyze the structure and structural dynamics of interfaces in a surface-specific manner. Its implementation, however, has so far remained limited to the pump-probe geometry, with its inherent restrictions. Here we present 2D SFG experiments utilizing a novel noncollinear geometry of four incident laser pulses generating a 2D SFG response, analogous to the triangle geometry applied in bulk-sensitive 2D infrared spectroscopy. This approach allows for background-free measurements of fourth-order nonlinear signals, which is demonstrated by measuring the fourth-order material response from a GaAs (110) surface. The implementation of phase-sensitive detection and broadband excitation pulses allows for both highest possible time resolution and high spectral resolution of the pump axis of a measured 2D SFG spectrum. To reduce the noise in our spectra, we employ a referencing procedure, for which we use noncollinear pathways and individual focusing for the signal and local oscillator beams. The 2D spectra recorded from the GaAs (110) surface show nonzero responses for the real and imaginary component, pointing to contributions from resonant electronic pathways to the χ((4)) response.

Dynamic analysis of a closed-circuit hydrostatic summation drive using bent axis motors

This article investigates the dynamic performance of a closed-circuit hydrostatic summation drive that has been carried out through system modeling and simulation. The proposed drive consists of a variable displacement piston pump and bent axis motors. The performances of the hydrostatic drive have been studied for its two different modes of operations, using single motor and two motors. The changing over of the drive mode is accomplished by on-/off-controlled direction control valve. Bondgraph simulation technique is used to model the hydrostatic drives. The characteristics of the loss coefficients of the drive are obtained from the steady-state model and they are identified through experimental investigation. Using them, the overall dynamic model of the hydrostatic drive has been validated experimentally. With respect to some critical parameters, the performances of the hydrostatic drive have also been studied.

PIV measurements of the unsteady flow structures in a volute centrifugal pump at a high flow rate

An experimental investigation based on PIV measurements is presented on the unsteady flow in a centrifugal pump with vaneless volute. The study has focused on the fluid–dynamic interaction between impeller and volute associated with the blade passage period when the pump operates well above design conditions (150 % of nominal flow rate). The test pump, which is fully transparent, has a 2D-shaped geometry and the impeller has 6 arc-shaped backward-curved blades. The flow in the mid-plane perpendicular to the pump axis was captured using fluorescent seeding particles and two fields of view (FOV), each with different magnification: a large FOV (low magnification) that covers a large portion of the impeller, volute and discharge duct, and a small FOV (high magnification) to observe the details of flow evolution at the tongue region. Results are presented on the in-plane phase-averaged relative and absolute velocities, turbulent kinetic energy, its production and vorticity fields. Their evolution over time during one blade passage is described, including a frequency analysis based on 32 blade positions. The spatial distribution of the spectral components at the blade-passing frequency and some harmonics reveals that the second harmonic is dominant in the narrow region of the volute at the tongue tip. The data obtained show that the fluid–dynamic blade–tongue interaction is dominated by high-vorticity sheets (positive and negative) being shed from the impeller channels, especially from the blade trailing edges, and their impingement on the tongue tip with subsequent cutting and distortion. The turbulence production is seen to be mainly concentrated in the wake regions from the blade leading and trailing edges and from the tongue tip. In particular, it gets maximum behind the blade trailing edge when the blade aligns with the tongue tip.

Modelling and Simulation of a Hydrostatic Transmission System using Two Motor Summation Drive

In this article simulation studies have been carried out on the dynamic performance of a hydrostatic transmission (HST) system using two motor summation drive. In this respect a closed loop HST system that consists of a variable displacement swashplate controlled axial piston pump and bent axis piston motors is considered. Bondgraph simulation technique is used to model the hydrostatic drive system. In that model an on-off control strategy is implemented to switch over the mode of operation from single motor to twin motor or vice-versa considering pressure as a parameter. The system’s performance has been analysed with respect to typical load cycle of a machine where such drive is incorporated. The effects of variation of critical parameters of the system on the performance of the system are studied through simulation.

Test Research on the New Electromechanical Axial-Flow Pump with Advantages of Small Vibration and Noise

For the vibration and noise of conventional axial-flow pumps being oppressive, a new electromechanical axial-flow pump with advantages of small vibration and noise had been designed, which integrated the impeller into drive electromotor by combining the rotor of motor and the blade of impeller. The new electromechanical axial-flow pump not only had small size and high efficiency, but also can greatly reduce vibration and noise by taking off the drive axis of pump. Performance tests had been done for the pump and results showed that the efficiency and head were very close to design value. Vibration and noise tests had also been done, results showed that vibration acceleration levels on the feet of pump base could be less than 110dB and airborne noise levels could be less than 75dB, which would be smaller than conventional axial-flow pumps.

Ultrabroadband femtosecond two-dimensional ultraviolet transient absorption

We present a broadband two-dimensional transient absorption setup for the UV around 300 nm with a time resolution of 150 fs. A narrowband, frequency tunable pump pulse and a broadband probe pulse are generated from the output of a noncollinear optical parametric amplifier operated at 20 kHz repetition rate and combined in a spectrally resolved transient absorption experiment. The high repetition rate and low noise of the setup allow us to acquire high quality two-dimensional data as a function of time delay with an unsurpassed frequency window of 10,000 and 8000 cm(-1) along the probe and pump axis, respectively. The performance of the setup is demonstrated on 2,5-Diphenyloxazol dissolved in cyclohexane.

Lipopolysaccharide hyperpolarizes guinea pig airway epithelium by increasing the activities of the epithelial Na+ channel and the Na+-K+ pump

Earlier, we found that systemic administration of lipopolysaccharide (LPS; 4 mg/kg) hyperpolarized the transepithelial potential difference (V(t)) of tracheal epithelium in the isolated, perfused trachea (IPT) of the guinea pig 18 h after injection. As well, LPS increased the hyperpolarization component of the response to basolateral methacholine, and potentiated the epithelium-derived relaxing factor-mediated relaxation responses to hyperosmolar solutions applied to the apical membrane. We hypothesized that LPS stimulates the transepithelial movement of Na(+) via the epithelial sodium channel (ENaC)/Na(+)-K(+) pump axis, leading to hyperpolarization of V(t). LPS increased the V(t)-depolarizing response to amiloride (10 μM), i.e., offset the effect of LPS, indicating that Na(+) transport activity was increased. The functional activity of ENaC was measured in the IPT after short-circuiting the Na(+)-K(+) pump with basolateral amphotericin B (7.5 μM). LPS had no effect on the hyperpolarization response to apical trypsin (100 U/ml) in the Ussing chamber, indicating that channel-activating proteases are not involved in the LPS-induced activation of ENaC. To assess Na(+)-K(+) pump activity in the IPT, ENaC was short-circuited with apical amphotericin B. The greater V(t) in the presence of amphotericin B in tracheas from LPS-treated animals compared with controls revealed that LPS increased Na(+)-K(+) pump activity. This finding was confirmed in the Ussing chamber by inhibiting the Na(+)-K(+) pump via extracellular K(+) removal, loading the epithelium with Na(+), and observing a greater hyperpolarization response to K(+) restoration. Together, the findings of this study reveal that LPS hyperpolarizes the airway epithelium by increasing the activities of ENaC and the Na(+)-K(+) pump.

Automated 2D IR spectrometer mitigates the influence of high optical densities

Two-dimensional infrared spectroscopy is a powerful tool for studying molecular structure and kinetics. However, standard ways of implementing the technique are not amenable to samples with high optical densities. In this paper, we demonstrate that a shaper-based automated 2D IR spectrometer largely compensates for most of the distortions caused by high optical densities. By comparing a series of 2D IR spectra collected with varying concentrations and sample thicknesses, we find that high quality 2D IR spectra can be obtained at optical densities of >1.2 when these spectra are collected using a pulse shaping method recently developed in our lab. Furthermore, distortions due to high OD primarily appear along the pump axis and are largely absent along the probe axis. Using this knowledge, we have applied our approach to study a high optical density sample of a truncated form of the human islet amyloid peptide that is involved in Type 2 diabetes. Our methodology promises to aid in the interpretation of 2D IR lineshapes for systems where the optical density cannot be controlled, such as in protein folding or chemical reactions where large changes in optical density occur during the kinetics.

Research and Development of Inclined Wave-Energy Pump. (I). Effect of Floats and Wave Converters of Inclined Double-Acting Pumps on Flow Characteristics.

A newly developed, inclined double-acting wave energy pump which can be designed effectively to inclined beach bottoms and the variation of wave periods has been experimentally investigated. In order to improve the pump performance the reciprocating moving parts, a pair of float-pistons have to be tuned with wave periods and take advantage of horizontal forces of the waves, which provides an idea of variable geometry. The pump, with variable axis angle, is operated in double-action mode in which water is pressurized by both up and down motions of the float-pistons. Model test pumps with rectangular and cylindrical floats were tested to determine the effect of the pump axis angle (θ), wave period (Tw) and some kinds of horizontal wave energy converters with an inclined plate. It is shown in this paper that an optimum pump axis angle exists in terms of the pump performance, and the combination of the cylindrical type float with the inclined wave energy converter results in increased pump efficiency on a large scale.

In vitro and in vivo evaluations of the antithrombogenic properties of the spiral vortex pump for temporary left heart bypass.

From conception to realization, the design emphasis of the spiral vortex diaphragm pump has been on promoting efficient blood flow patterns in order to lower thrombogenicity. The tracer method was used to visualize flow patterns in this pump and the results were compared with those of a conventional diaphragm pump with paraxial inlet and outlet ports. During diastole, the flow through a 45 degrees angled inlet is tangential to the axis of the pump forming a continuous vortex central along the pump axis. During systole, the vortex converges to pass through the apically located outlet. No areas of turbulence or stasis could be found, whilst in the conventional pump only random flow with recirculation could be demonstrated. Dye washout tests confirmed good washout at the periphery of this pump with no signs of stasis. However, large areas of stagnation with incomplete washout at diaphragm-housing (D-H) junctions were observed in the conventional pump. The comparative in vitro haemolysis test revealed that the level of free plasma haemoglobin was doubled in a commercially available pump compared with that of the spiral vortex pump. No thrombus formed within the pump housing after up to 50 hours of pumping in five acute animal experiments without postoperative anticoagulants. However, thrombi were found at the D-H junction of this pump due to imperfect fabrication techniques in one of the four sheep that survived 14-21 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Compression ignition engine using composite emulsified fuel. Engine performances and combustion characteristics under transient operation.

Transient engine performance, fuel injection and combustion characteristics of prechamber-type compression ignition engines operated with a composite emulsified fuel (composed of gas oil, water and methanol) were investigated. As a result, response of engine speed of composite fuel operation was found to be the same as the gas-oil operation. However, The start of injection timing under transient running was slower than that of steady-state operation. The retarded and fluctuated start of injection timing was caused by the vibration of the pump axis under transient running and the unstable air content of a composite fuel. Therefore the retarded and fluctuated start of injection timing increased the ignition lag and its fluctuation.

Fluid-Structure Interaction Forces at Pump-Impeller-Shroud Surfaces for Rotordynamic Calculations

Governing equations of motion are derived for a bulk-flow model of the leakage path between an impeller shroud and a pump housing. The governing equations consist of a path-momentum, a circumferential-momentum, and a continuity equation. The fluid annulus between the impeller shroud and pump housing is assumed to be circumferentially symmetric when the impeller is centered; i.e., the clearance can vary along the pump axis but does not vary in the circumferential direction. A perturbation expansion of the governing equations in the eccentricity ratio yields a set of zeroth and first-order governing equations. The zeroth-order equations define the leakage rate and the circumferential and path velocity distributions and pressure distributions for a centered impeller position. The first-order equations define the perturbations in the velocity and pressure distributions due to either a radial-displacement perturbation or a tilt perturbation of the impeller. Integration of the perturbed pressure and shear-stress distribution acting on the rotor yields the reaction forces and moments acting on the impeller face. Calculated results yield predictions of possible resonance peaks of the fluid within the annulus formed by the impeller shroud and housing. Centrifugal acceleration terms in the path-momentum equation are the physical origin of these unexpected predictions. For normalized tangential velocities at the inlet to the annulus, uθ0(0) = Uθ0(0)/Riω of 0.5, the phenomenon is relatively minor. As uθ0(0) is increased to 0.7, sharp peaks are predicted. Comparisons for rotordynamic coefficient predictions with test results of Bolleter et al. show reasonable agreement for cross-coupled stiffness and direct damping terms. Calculated results are provided which make comparisons between seal forces and shroud forces for a typical impeller/wear-ring-seal combination.