Hydraulic Performance Tests Research Articles

Energy Loss Analysis of Novel Self-Priming Pump Based on the Entropy Production Theory

The conventional method cannot explicitly confirm the location and type of the energy loss, therefore this paper employs the entropy production theory to systematically analyze the category, magnitude and location of hydraulic loss under different blade thickness distribution. Based on the analysis, the turbulent entropy and viscosity entropy produced by the separation of boundary layer at the trialing edge are major factors leading to the hydraulic loss. In addition, the separation of the boundary layer can not only cause the energy loss, but also block the passage of the impeller and reduce the expelling coefficient of the blade. Therefore, the hydraulic performance of the blades with increment thickness distribution is obviously better than the decrement one. Further, the flow rate has different influence on the three types of entropy production. Meanwhile, the pressure pulsation on the working surface was investigated. It was concluded that with flow rates increasing, the amplitude of pressure pulsation firstly decreases and then smoothly improves, and reaches the minimum under design flow rate. Finally, the optimal blade was obtained, and the relevant hydraulic performance test was performed to benchmark the simulation result. This research can provide the theoretical reference for designing the reasonable thickness distribution of the blades.

수차 발전 운용 데이터 분석을 통한 50 MW급 프란시스 러너 설계

The hydraulic power is the eco-friendly power which has the long service life and low power cost. The power amount of the hydraulic turbine is influenced by the environmental conditions of the dam where it is installed. The operation data of the 50 MW class Francis turbine which was installed 30 years ago shows that the water level of its dam has been dropped for the last 5 years. This presents that 90% of its original power has been produced for the last 5 years. Therefore, for its efficient operation, its runner is decided to be redesigned for fitting to the changed operation condition. This study presents the whole design process from the preliminary design to its verification. The hydraulic performance test has been conducted by IEC 60193.

Influence of Dentation Angle of Labyrinth Channel of Drip Emitters on Hydraulic and Anti‐Clogging Performance

AbstractThe geometric parameters of labyrinth channels play an important role in the hydraulic and anti‐clogging performance of drip emitters. In this study, the flow fields, individual representative sands and sand groups in the labyrinth channel of emitters, with dentation angles of 90°, 60°, 45° and 30°, were firstly simulated using a computational fluid dynamics discrete element method (CFD–DEM) of coupling. Particle tracking velocimetry (PTV) was used to trace individual representative sands. The numerical results were verified with clear water hydraulic performance tests and muddy water anti‐clogging performance tests. The results suggest that the discharge coefficient and flow exponent declined when the dentation angle of the labyrinth channel was reduced. A large number of sand groups were observed to enter the vortex areas and move in a circular manner. The time it took for particles to pass through the labyrinth channel lengthened when the velocity decreased and as a result, the probability of emitter clogging increased. Therefore, by using a recommended angle range of 90° to 60° and a combined higher hydraulic performance level, emitters were less likely to clog. It was a novel approach to adopt a CFD–DEM coupling method to conduct numerical analysis of individual sand particles and sand groups in the investigation of emitter anti‐clogging issues. The findings will increase the design efficiency of flow channels and will save human and material resources. © 2018 John Wiley & Sons, Ltd.

Effects of Distance of Breaker Disk on Performance of Ejector Type Microbubble Generator

Generating methods of microbubble are various. One of them is ejector type microbubble generator. Ejector type microbubble generator has advantage that equipment to supply air into water is not essential. However, size of generated bubbles by ejector type microbubble generator are relatively larger than that of other methods. So, many researcher has been studied to improve performance of generator using porous films and shear and rotary speed in nozzle. In this research, to improve performance of ejector type microbubble generators, breaker disk was used. And, two kinds of test were performed to verify effect of breaker disk. In hydraulic performance test, when the distance of breaker disk is close to nozzle, supplied air was decreased. Because of backward flow and resistance of fluid with it, pressure drop was decreased. In bubble dissolution tests, when the distance of breaker disk is close to the nozzle, the chance to collision between breaker disk and large bubbles was increased. So, high performance of mass transfer coefficient and bubble dissolution rate are shown in this experiments.

Optimization design of multiphase pump impeller based on combined genetic algorithm and boundary vortex flux diagnosis

A novel optimization design method for the multiphase pump impeller is proposed through combining the quasi-3D hydraulic design (Q3DHD), the boundary vortex flux (BVF) diagnosis, and the genetic algorithm (GA). The BVF diagnosis based on the Q3DHD is used to evaluate the objection function. Numerical simulations and hydraulic performance tests are carried out to compare the impeller designed only by the Q3DHD method and that optimized by the presented method. The comparisons of both the flow fields simulated under the same condition show that (1) the pressure distribution in the optimized impeller is more reasonable and the gas-liquid separation is more efficiently inhibited, (2) the scales of the gas pocket and the vortex decrease remarkably for the optimized impeller, (3) the unevenness of the BVF distributions near the shroud of the original impeller is effectively eliminated in the optimized impeller. The experimental results show that the differential pressure and the maximum efficiency of the optimized impeller are increased by 4% and 2.5%, respectively. Overall, the study indicates that the optimization design method proposed in this paper is feasible.

The comparison between the acquisition vibration data obtained by different types of transducers for hydraulic turbine head cover

Based on the summaries of the rules about the vibration measurement for hydro-generator sets with respect to relevant standards, the key issues of the vibration measurement, such as measurement modes, the transducer selection are illustrated. In addition, the problems existing in vibration measurement are pointed out. The actual acquisition data of head cover vertical vibration respectively obtained by seismic transducer and eddy current transducer in site hydraulic turbine performance tests during the rising of the reservoir upstream level in a certain hydraulic power plant are compared. The difference of the data obtained by the two types of transducers and the potential reasons are presented. The application conditions of seismic transducer and eddy current transducer for hydro-generator set vibration measurement are given based on the analysis. Research subjects that should be focused on about the topic discussed in this paper are suggested.

Hydraulic Performance Assessment of Lesa at low Pressure

AbstractTo assist with the selection of appropriate low elevation spray application (LESA) technology, hydraulic performance tests at low pressure were conducted. The main structural parameters in this study were the aboveground height (A), spacing between the sprinklers (B), travel speed (C), and sprinkler nozzle diameter (D). An orthogonal array with four factors and three levels was selected, and the direct analysis technique was used to analyze the test data. Results show that the influencing factors in decreasing order of importance were as follows: CDBA for application depth; BACD for irrigation uniformity (CU); ACBD for application efficiency; CDBA for surface runoff; and CDBA for soil water content. The highest application efficiency obtained during the experiments was 95.1%, and the highest uniformity coefficient obtained was 96.4%. The application efficiency was high when the sprinkler height was low. CU was high when the spacing between the sprinklers was small. The surface runoff amount was low when the travel speed was high. The application depth and surface runoff were higher when the sprinkler nozzle diameter was larger. Copyright © 2016 John Wiley & Sons, Ltd.

Characterisation of bentonite polymer for bottom liner use

This paper aims to study the hydromechanical behaviour and the clay polymer interaction of amended Ca-bentonite. Specimens were formed by mixing Ca-bentonite with two soluble polyelectrolyte polymer powders. Some important parameters are studied: swelling, water adsorption and hydraulic performance for landfill applications. Tests are performed with tap water and synthetic leachate (SL) to reproduce the hydrochemical phenomena. Hydraulic performance tests were performed with an oedopermeameter. Tests results show that polymers tend to reduce the permeability when in contact with the SL. Water adsorption and free swell index tests confirmed that adsorption, swelling and permeability parameters depend on the clay polymer mixtures and that adding polymers improves the clay properties. Each polymer’s charges has a different effect: the anionic polymer gives low permeability to the mixture, and the cationic polymer enhances the bentonite swell ability and water retention, which can be used also as a performance index.

Constant Value Adjusting Method Based on Characteristic Parameters of Process

This paper presents a new method to solve the problem of speed and pressure constant value adjustment in the high-power hydraulic pumps and hydraulic motors performance test system which is based on energy recycling technology. The constant value control method is designed based on characteristic parameters of the process, including control resolution, overshoot and adjustment time. Experiments were implemented to verify the effectiveness of the proposed method. Experimental result shows that the proposed method reduced the test time by about 52.4% than before. The convergence rate of the constant value adjusting process and the test efficiency are significantly improved by the proposed method.

Thermal hydraulic performance testing of printed circuit heat exchangers in a high-temperature helium test facility

In high-temperature gas-cooled reactors, such as a very high temperature reactor (VHTR), an intermediate heat exchanger (IHX) is required to efficiently transfer the core thermal output to a secondary fluid for electricity generation with an indirect power cycle and/or process heat applications. Currently, there is no proven high-temperature (750–800 °C or higher) compact heat exchanger technology for high-temperature reactor design concepts. In this study, printed circuit heat exchanger (PCHE), a potential IHX concept for high-temperature applications, has been investigated for their heat transfer and pressure drop characteristics under high operating temperatures and pressures.Two PCHEs, each having 10 hot and 10 cold plates with 12 channels (semicircular cross-section) in each plate are fabricated using Alloy 617 plates and tested for their performance in a high-temperature helium test facility (HTHF). The PCHE inlet temperature and pressure were varied from 85 to 390 °C/1.0–2.7 MPa for the cold side and 208–790 °C/1.0–2.7 MPa for the hot side, respectively, while the mass flow rate of helium was varied from 15 to 49 kg/h. This range of mass flow rates corresponds to PCHE channel Reynolds numbers of 950 to 4100 for the cold side and 900 to 3900 for the hot side (corresponding to the laminar and laminar-to-turbulent transition flow regimes). The obtained experimental data have been analyzed for the pressure drop and heat transfer characteristics of the heat transfer surface of the PCHEs and compared with the available models and correlations in the literature. In addition, a numerical treatment of hydrodynamically developing and hydrodynamically fully-developed laminar flow through a semicircular duct is presented. Relations developed for determining the hydrodynamic entrance length in a semicircular duct and the friction factor (or pressure drop) in the hydrodynamic entry length region for laminar flow through a semicircular duct are given. Various hydrodynamic entrance region parameters, such as incremental pressure drop number, apparent Fanning friction factor, and hydrodynamic entrance length in a semicircular duct have been numerically estimated.

Signal Acquisition and Processing in Hydraulic Components Test System

The key to the performance test system for hydraulic components is to realize real, fast and accurate signal acquisition and processing. By analysis the analog and digital signal processing during hydraulic components Performance testing, a new signal flow scheme is proposed. It described in detail the acquisition and processing method of serial signals and PLC signals, thus solving the lag and distortion during signal processing and realizing the real-time display of data and the automatic report of performance parameters during hydraulic components testing process.

Innovative Hydraulic Power Take-Off Construction and Performance Tests for Wave Energy Conversion

This document describes and demonstrates the features of a new innovative hydraulic Power take-Off (PTO) to be used for Wave Energy Conversion. This device is able to transform low frequency oscillating movement into a continuous high frequency angular speed, absorbing high fluctuated torque at the input shaft, which can reach up to 8000Nm. Moreover, the major breakthrough of this device is that it can control the braking torque through the modification of some geometrical parameters, L and R, and through the activation of more than one hydraulic cylinder together with the pressure. The output shaft of the PTO is able to rotate at different continuous rated speed through the actuation on a specific control valve at the inlet of the hydraulic motor. Tests to check the behavior of the PTO related to the smoothening of the power output and concerning the time needed to increase the high pressure and the time available after the accumulation of some quantity of energy in different initial conditions are presented.

The Development and Performance Analysis on Static Experiment System of Ship Models

To conduct ship model inclining experiments and floating state adjustment experiments, a static experiment system is developed, including research and development of hydrostatic flume, connecting frame, attitude instrument and data acquisition and analysis processing module. And the work principle of the system is discussed. Furthermore, ship model inclining experiment, floating state adjusting experiment, and roll, pitch, heave free decay experiment are conducted to analyse the performance of this system. Results of the experimental indicate that the system has a satisfactory testing precision. In the model inclining experiments, relative error of vertical coordinate of center of gravity of the ship model is 1.5%, relative error of the longitudinal coordinate is 0.18%; in the floating state adjusting experiment, standard error of transverse inclination is 0.06 degree, standard error of longitudinal inclination is 0.03 degree, standard error of heaving measurement is 0.15mm; the free decay experiment proofs that the experiment system can realize dynamic measurement of roll, pitch and heave. This experimental system with high precision has a good application prospect which can be used in ship model inclining experiment, floating state adjusting experiments, as well as model hydraulic performance test study.

Experimental study of the effect of blade tip clearance and blade angle error on the performance of mixed-flow pump

The hydraulic performance test of the mixed-flow pump has been carried out through selecting different blade tip clearances and various blade angle errors. The ratio of the mixed-flow pump efficiency reduction and the blade tip clearance variation (Δη/Δδ) varies with the flow rate coefficient ϕ revealing a parabolic trend. An empirical equation has been developed for the mixed-flow pump model by parabolic fitting. For the same blade tip clearance variation Δδ, the mixed-flow pump efficiency reduction Δη increases rapidly as the flow rate rises. For any given flow rate, the efficiency, the head and the shaft power of the mixed-flow pump all decrease with the increase of the blade tip clearance. Among them, the efficiency reduction Δη varies approximately linearly with the blade tip clearance variation Δδ. When the angle of an individual blade of the mixed-flow pump has a deviation, the performance curves will move and change. These curves have consistent change directions with the performance curves under the condition of all the blades rotated at the same time, but have smaller offset and lower range of variation. When an individual blade angle error changes to ±2°, the optimal efficiency of the mixed-flow pump will have no significant difference. When the individual blade angle error increases to ±4°, the optimal efficiency will decrease by 1%.

The comparative analysis of the current-meter method and the pressure-time method used for discharge measurements in the Kaplan turbine penstocks

The paper presents experiences gathered during many years of utilizing the current-meter and pressure-time methods for flow rate measurements in many hydropower plants. The integration techniques used in these both methods are different from the recommendations contained in the relevant international standards, mainly from the graphical and arithmetical ones. The results of the comparative analysis of both methods applied at the same time during the hydraulic performance tests of two Kaplan turbines in one of the Polish hydropower plant are presented in the final part of the paper. In the case of the pressure-time method application, the concrete penstocks of the tested turbines required installing a special measuring instrumentation inside the penstock. The comparison has shown a satisfactory agreement between the results of discharge measurements executed using the both considered methods. Maximum differences between the discharge values have not exceeded 1.0 % and the average differences have not been greater than 0.5 %.

Experimental study of the pressure fluctuations in a pump turbine at large partial flow conditions

Frequent shifts of output and operating mode require a pump turbine with excellent stability. Current researches show that large partial flow conditions in pump mode experience positive-slope phenomena with a large head drop. The pressure fluctuation at the positive slope is crucial to the pump turbine unit safety. The operating instabilities at large partial flow conditions for a pump turbine are analyzed. The hydraulic performance of a model pump turbine is tested with the pressure fluctuations measured at unstable operating points near a positive slope in the performance curve. The hydraulic performance tests show that there are two separated positive-slope regions for the pump turbine, with the flow discharge for the first positive slope from 0.85 to 0.91 times that at the maximum efficiency point. The amplitudes of the pressure fluctuations at these unstable large partial flow conditions near the first positive slope are much larger than those at stable operating condtions. A dominant frequency is measured at 0.2 times the impeller rotational frequency in the flow passage near the impeller exit, which is believed to be induced by the rotating stall in the flow passage of the wicket gates. The test results also show hysteresis with pressure fluctuations when the pump turbine is operated near the first positive slope. The hysteresis creates different pressure fluctuations for those operation points even though their flow rates and heads are similar respectively. The pressure fluctuation characteristics at large partial flow conditions obtained by the present study will be helpful for the safe operation of pumped storage units.

Study on inducer and impeller of a centrifugal pump for a rocket engine turbopump

A hydraulic performance test is conducted for a fuel pump of a liquid rocket engine turbopump. The pump driven by an electric motor is tested in a water environment. Experimental results indicate that the inducer has a negligible effect on the head and efficiency of the pump but a significant effect on the cavitation performance. Additionally, an autonomous inducer test is carried out to investigate the effect of the inducer on the pump performance in more detail, and it is found out that the pump reaches a critical cavitation point when the inducer head is dropped by 55%. A reduction of required net positive suction head of the centrifugal pump by attachment of an inducer is also calculated considering the flow interference between the inducer and the centrifugal impeller, and it is found that the calculation shows a reasonable agreement with the test.

Numerical Simulation on the Hydraulic Performance and Model Test of Slanted Axial Pumping System

In order to study on hydraulic performance of slanted 15° axial pumping system,the three dimensional steady turbulent flow in pumping system is simulated based on computational fluid dynamics software ANSYS CFX,applying the RNG k-e turbulent flow model,scalable wall functions and the multiple reference frames.The flow detail of the whole slanted axial pumping system is attained.The relation between hydraulic performance of outlet cross sections with rotating impeller and the relative height of outlet cross sections and the stress distribution of impeller are analyzed,as well as the relative velocity distribution near the airfoil cross sections under the designed condition.The hydraulic moments are calculated based on the numerical results under different conditions,and the changing features of hydraulic moment on blades with flow rates are analyzed.The reference nominal height of pumping system can be marked from(0.7-0.9) D.The comparison of simulation results and experiment data show that the biggest absolute error is 5.01% between predictive and experimental pumping system efficiency,especially the relative error of head and the absolute error of efficiency are less than 3.5% at the best efficiency and designed operating conditions,which validate the validity of the numerical simulation.

Comparative performance of ‘U-tube’ and ‘coaxial’ loop designs for use with a ground source heat pump

Abstract The installation cost and coefficient of performance (COP) of a ground source heat pump (GSHP) system can be greatly affected by the design of its ground loop. An experimental investigation was conducted to compare the performance of two loop designs for use with the ground source heat pump of an ‘energy pile’ installation or a conventional borehole system. A coaxial loop (a 40 mm OD coaxial tube with a 20 mm OD interior pipe) and a U-tube (20 mm OD pipes) of a length of 72 m were constructed, tested and analysed in terms of ground heat extraction capability and hydraulic flow characteristics. The use of the coaxial loop design could potentially reduce the cost of drilling boreholes and make the installation easier on site, as the effective diameter would be smaller than a comparable U-tube with the same mass flow rate, considering that the U-tube requires a minimum 10 mm spacer between the legs. Hydraulic performance tests have shown that the U-tube achieved the transitional-turbulent flow at a glycol flow rate of approximately 0.14L/s, whereas the flow in the coaxial remained laminar across the glycol flow rate range of 0.05–0.25L/s. Heat pump performance tests have shown that the U-tube achieved a COP of at least 0.08 greater than the coaxial loop across the range of glycol flow rates investigated, while the heat output was at least 12% greater when using the U-tube. Therefore, it can be concluded that the coaxial loop in its current form is seen not to add any performance benefit against the U-tube.

Application of Neural-Fuzzy System in Twin-Turbo Hydraulic Torque Converter's Performance Testing

Twin-turbo hydraulic torque converter's performance testing is very important in the product's development and production. According to the needs of data processing and analysis in performance testing, A neural-fuzzy algorithm was used to analyze the test data in this paper. It can improve computing speed and programming capability, decrease artificial involved times, realize the data analysis processing's automation. The application shows that the digital information's relationship can be expressed very well by this method. At the same time, this method has high degree of accuracy and quick speed on data recognition and can satisfy the requirement of designing.