Hydraulic Applications Research Articles

Использование регулируемой асинхронной машины двойного питания в синхронном режиме

Owing to the rapid progress in converter engineering, double-fed machines made on the basis of a wound-rotor asynchronous machine are finding wide use both as generators (in wind power engineering and in small-scale hydraulic power engineering applications) and as motors for applications in which the rotation frequency has to be adjusted within a relatively narrow (30—40%) range, and in which certain limitations are imposed on the frequency converter power capacity. In a number of cases, the technology of using these machines as generators or motors dictates the need of running them with a close-to-synchronous rotation frequency, i.e., without adjusting it. Under such conditions, it is proposed to shift the machine in a synchronous mode of its operation by using only the frequency converter’s rectifying part that supplies power to the wound-rotor asynchronous machine’s (WRAM) rotor winding. The use of such solution will make it possible to generate a significantly larger reactive power into the electric network and to use the generator itself in a more efficient manner. The article presents the WRAM mathematical model that makes it possible to study, within the same structure, all WRAM operation modes, including the use of the machine for its direct purpose (adjusting the rotation frequency up and down with respect to its synchronous level), as a synchronous generator with generating significant reactive power to the network, and also as a squirrel-cage asynchronous generator. An analysis of the time curves obtained on the developed mathematical model has shown its high efficiency and adequacy. It also has shown that the proposed solution for switching a WRAM to operate in synchronous and asynchronous modes of operation is efficient and feasible.

Image processing technique for hydraulic application

Image processing technique for hydraulic application

Analysis of worldwide Portland Cement Market Size and Their Properties

Portland cement concrete that's Portland cement when combined with water, hardens into a solid mass. qualitative analysis of cement raw materials gave knowledge into the substance properties of cement. during this paper we are discussing about the varied chemical composition and properties of hydraulic cement. during this paper we also are discussing about the market size of hydraulic cement and application of cement and their ratio.

Some considerations on numerical schemes for treating hyperbolicity issues in two-layer models

Multi-layer depth-averaged models are widely employed in various hydraulic engineering applications. Yet, such models are not strictly hyperbolic. Their equation systems typically lose hyperbolicity when the relative velocities between layers become too large, which is associated with Kelvin–Helmholtz instabilities involving turbulent momentum exchanges between the layers. Focusing on the two-layer case, we present a numerical improvement that locally avoids the loss of hyperbolicity. The proposed modification introduces an additional momentum exchange between layers, whose value is iteratively calculated to be strictly sufficient to keep the system hyperbolic. The approach can be easily implemented in any finite volume scheme and there is no limitation concerning the density ratio between layers. Numerical examples, employing both HLL-type and Roe-type approximate Riemann solvers, are reported to validate the method and its key features.

Note on the stability of viscous roll waves

In this note, we announce a complete classification of the stability of periodic roll-wave solutions of the viscous shallow water equations, from their onset at Froude number F≈2 up to the infinite Froude limit. For intermediate Froude numbers, we obtain numerically a particularly simple power-law relation between F and the boundaries of the region of stable periods, which appears potentially useful in hydraulic engineering applications. In the asymptotic regime F→2 (onset), we provide an analytic expression of the stability boundaries, whereas in the limit F→∞, we show that roll waves are always unstable.

Standardized Hydraulic Conductivity Testing of Compacted Sand-Bentonite Mixtures

AbstractCompacted sand-bentonite mixtures can be used as engineered barriers (liners) for waste containment applications. A primary consideration for such applications is the ability of the mixtures to achieve a suitably low hydraulic conductivity, k, typically ≤1.0 × 10−9 m/s, based on permeation with water in the laboratory. The purpose of this study was to evaluate in a systematic manner the applicability of ASTM D5084-10 for the measurement of k of compacted sand-bentonite mixtures. Final degrees of saturation, Sf, for 4 of the 19 test specimens were outside of the required range 95 % ≤ Sf ≤ 105 %, even though the measured k values for these 4 specimens were consistent with those tested under the same conditions with values of Sf that met the standard. Thus, Sf apparently was an unreliable measure of true saturation for the materials tested in this study. Otherwise, the results indicated that conservatively high values of k were measured for the largest specimen size, the highest applied hydraulic gradient, and the highest ionic strength of the permeant water. A difference in the method of hydraulic gradient application had essentially no effect on the magnitude of k. Finally, as expected, specimens containing the highest amount of bentonite (i.e., 15 % by dry weight) resulted in the lowest values of k, although calculation of some values of k for one specimen were negative (k < 0), which was attributed to swelling of the specimen during permeation and the manner in which k was calculated based on ASTM D5084-10.

A new methodology for hydro-abrasive erosion tests simulating penstock erosive flow

Hydro-abrasive resistance is an important property requirement for hydroelectric power plant penstock coating systems used by EDF. The selection of durable coating systems requires an experimental characterization of coating performance. This can be achieved by performing accelerated and representative laboratory tests. In case of severe erosion induced by a penstock flow, there is no suitable method or standard representative of real erosive flow conditions. The presented study aims at developing a new methodology and an associated laboratory experimental device. The objective of the laboratory apparatus is to subject coated test specimens to wear conditions similar to the ones generated at the penstock lower generatrix in actual flow conditions. Thirteen preselected coating solutions were first been tested during a 45 hours erosion test. A ranking of the thirteen coating solutions was then determined after characterisation. To complete this first evaluation and to determine the wear kinetic of the four best coating solutions, additional erosion tests were conducted with a longer duration of 216 hours. A comparison of this new method with standardized tests and with real service operating flow conditions is also discussed. To complete the final ranking based on hydro-abrasive erosion tests, some trial tests were carried out on penstock samples to check the application method of selected coating systems. The paper gives some perspectives related to erosion test methodologies for materials and coating solutions for hydraulic applications. The developed test method can also be applied in other fields.

Manufacturing of nickel based cermet coatings by the HVOF process

Advanced particle diagnostic technology has been applied to establish process parameters to deposit high quality nickel based carbide cermet coatings for marine hydraulic applications. The cermet coatings are produced via the kerosene fuelled high velocity oxygen fuel (HVOF) spray process, which uses a hypersonic flame jet to melt and accelerate feedstock particles onto the component surfaces. The traditional ‘trial and error’ procedure is not technically robust, as well as being costly and time consuming. Instead, a superior method is implemented in the current study that performs real time monitoring of the process parameters associated with the HVOF flame jets. Subsequently, coatings can be produced with the knowledge of the inflight particle size, temperature and velocity profiles. The analytical results allow identification of suitable coating process parameters, which translate to coatings of lower porosity and enhanced mechanical performance.

Stability of Viscous St. Venant Roll Waves: From Onset to Infinite Froude Number Limit

We study the spectral stability of roll-wave solutions of the viscous St. Venant equations modeling inclined shallow-water flow, both at onset in the small-Froude number or "weakly unstable" limit $F\to 2^+$ and for general values of the Froude number $F$, including the limit $F\to +\infty$. In the former, $F\to 2^+$, limit, the shallow water equations are formally approximated by a Korteweg de Vries/Kuramoto-Sivashinsky (KdV-KS) equation that is a singular perturbation of the standard Korteweg de Vries (KdV) equation modeling horizontal shallow water flow. Our main analytical result is to rigorously validate this formal limit, showing that stability as $F\to 2^+$ is equivalent to stability of the corresponding KdV-KS waves in the KdV limit. Together with recent results obtained for KdV-KS by Johnson--Noble--Rodrigues--Zumbrun and Barker, this gives not only the first rigorous verification of stability for any single viscous St. Venant roll wave, but a complete classification of stability in the weakly unstable limit. In the remainder of the paper, we investigate numerically and analytically the evolution of the stability diagram as Froude number increases to infinity. Notably, we find transition at around $F=2.3$ from weakly unstable to different, large-$F$ behavior, with stability determined by simple power law relations. The latter stability criteria are potentially useful in hydraulic engineering applications, for which typically $2.5\leq F\leq 6.0$.

A variational hydraulic fracturing model coupled to a reservoir simulator

A variational fracture model coupled to an external reservoir simulator through variable exchange is presented. While convergence is not optimal without Jacobian matrices with which fully coupling can provide, the presented coupling scheme is versatile enough that the reservoir simulator could be easily replaced with any other simulator. A variational approach to fracture is introduced first by comparison to the classic Griffith criteria, and is then expanded to include poro-elasticity and in-situ stresses that are required in hydraulic applications. The coupled code has been tested against existing analytical solutions of fluid-driven fracture propagation. Finally, illustrative examples are shown to demonstrate that the methodology's ability to simulate multi fracture interaction with the unified approach for turning and merging fractures.

Characterization of Granular Materials with Internal Pores for Hydraulic Calculations Involving Fixed and Fluidized Beds

This study focuses on the characterization of porous granular materials for applications in hydraulics of fixed and fluidized beds. Different density measurement procedures were tested using five different sieved fractions of each of zeolite, activated carbon, and anthracite coal media to compare these procedures and to ascertain the effect of the density measurement method used on the calculation of other particle and bed properties. The mentioned particle and bed properties are the following: (i) particle density, (ii) particle size (equivalent diameter), (iii) sphericity, (iv) fixed-bed porosity, and (v) expanded-bed porosity during fluidization. The density of each of the 15 fractions was determined using four different methods: (i) cone test (ASTM C128-12), (ii) Le Châtelier flask method, (iii) soaking and straining, and (iv) skeletal density. The first three of these measure “wet density” (i.e., pores filled with liquid), the difference between them being in how the particles are saturated with liqu...

Water blocking effect caused by the use of hydraulic methods for permeability enhancement in coal seams and methods for its removal

To research techniques for removing the water blocking effect caused by hydraulic applications in coal seams, the use of surfactants is proposed, based on the mechanics of the water blocking effect. Centrifugal experiments were used to validate the effects of using surfactants; the results show that after dealing with vacuum saturation with water, the volume of micropores decreases, which results in a larger average pore size, and the volume of transitional pores, mesopores, macropores and total pores increases. Based on the distribution of pore size, the operation mode of “water infusion after gas extraction, then continuing gas extraction” is recommended to improve the volume of coal mine gas drainage. When the reflectance of vitrinite in coal samples is less than 1, using the surfactants Fast T, 1631, APG, BS can mitigate the damage caused by the water blocking effect. But when the reflectance of vitrinite is larger than 1.4, the damage caused by the water blocking effect can be increased. When the surfactant CMC is used in hydraulic applications, the capillary forces of coal samples are almost negative, which means the capillary force is in the same direction as the gas extraction. The direction of capillary forces benefits the gas flow. So, using CMC can play an active role in removing the water blocking effect. Centrifugal experiments confirm that using CMC can effectively remove the water blocking effect, which has a beneficial effect on improving the gas drainage volume.

A practical sensitivity analysis method for ranking sources of uncertainty in thermal–hydraulics applications

In application to thermal–hydraulic calculations by system codes, sensitivity analysis plays an important role for managing the uncertainties of code output and risk analysis. Sensitivity analysis is also used to confirm the results of qualitative Phenomena Identification and Ranking Table (PIRT). Several methodologies have been developed to address uncertainty importance assessment. Generally, uncertainty importance measures, mainly devised for the Probabilistic Risk Assessment (PRA) applications, are not affordable for computationally demanding calculations of the complex thermal–hydraulics (TH) system codes. In other words, for effective quantification of the degree of the contribution of each phenomenon to the total uncertainty of the output, a practical approach is needed by considering high computational burden of TH calculations. This study aims primarily to show the inefficiency of the existing approaches and then introduces a solution to cope with the challenges in this area by modification of variance-based uncertainty importance method. Important parameters are identified by the modified PIRT approach qualitatively then their uncertainty importance is quantified by a local derivative index. The proposed index is attractive from its practicality point of view on TH applications. It is capable of calculating the importance of parameters by a limited number of TH code executions. Application of the proposed methodology is demonstrated on LOFT-LB1 test facility.

Lumped Parameter Modelling of Cavitating Orifice Flow in Hydraulic Systems

Gaseous cavitation is an important issue that introduces negative effects on the performance of hydraulic systems. The lumped parameter modelling approach is widely adopted in the research of hydraulic applications due to its quickness and convenience to apply at the system level. For this reason, a novel lumped parameter model of cavitating orifice flow based on a control volume concept is presented in this paper. In particular, a procedure of calibrating the unknown model coefficients is provided by using the computational fluid dynamic (CFD) method as well as test data. A test rig for studying cavitation in an external gear pump is set up with a variable orifice at the inlet port. The four coefficients in the CFD cavitation model is first identified by the measured mass flow rate through the test orifice; then the CFD simulated fluid field offers required information including the average air mass fraction in downstream region to determine the two coefficients of lumped parameter (LP) model. To further verify the calibrated models, another test at a different pump speed is carried out to compare it to the model prediction. Good matching with experiments justifies the proposed approach and the calibration procedure. Suggestions for future work include extending the approach to the study of hydraulic valves and high-speed pumps.

Flood inundation mapping sensitivity to riverine spatial resolution and modelling approach

An innovative approach in the investigation of complex landscapes for hydraulic modelling applications is the use of terrestrial laser scanner (TLS) that can lead to a high-resolution digital elevation model (DEM). Another notable factor in flood modelling is the selection of the hydrodynamic model (1D, 2D and 1D/2D), especially in complex riverine topographies, that can influence the accuracy of flood inundation area and mapping. This paper uses different types of hydraulic–hydrodynamic modelling approaches and several types of river and riparian area spatial resolution for the implementation of a sensitivity analysis for floodplain mapping and flood inundation modelling process at ungauged watersheds. Four data sets have been used for the construction of the river and riparian areas: processed and unprocessed TLS data, topographic land survey data and typical digitized contours from 1:5000-scale topographic maps. Modelling approaches combinations consist of: one-dimensional hydraulic models (HEC-RAS, MIKE 11), two-dimensional hydraulic models (MIKE 21, MIKE 21 FM) and combinations of coupled hydraulic models (MIKE 11/MIKE 21) within the MIKE FLOOD platform. Historical flood records and estimated flooded area derived from an observed extreme flash-flood event have been used in the validation process using 2 × 2 contingency tables. Flood inundation maps have been generated for each modelling approach and landscape configuration at the lower part of Xerias River reach at Volos, Greece, and compared for assessing the sensitivity of input data and model structure uncertainty. Results provided from contingency table analysis indicate the sensitivity of floodplain modelling on the DEM spatial resolution and the hydraulic modelling approach.

Polymer Coating over Solid Particles with In Situ Thermal Curing

Solid particles coated by cross-linked polymer layers find applications in many areas, including hydraulic fracturing operations. In this study, a hot-melt resin coating process for solid particles is developed and optimized for hydraulic fracturing applications. Phenolic resin is used to coat the particles above its melting point and is subsequently cured in situ by hexamethylenetetramine (HMTA). The coating quality is then characterized by the surface morphology, acid solubility, and crush resistance of the resin-coated particles. The effects of various operating parameters on the coating performance are systematically studied. Among them, temperature is shown to play an especially important role. The coating process involves intricate coupling between resin rheology, HMTA mass transfer, and curing kinetics, all of which are profoundly influenced by temperature. Different constant temperature levels as well as controlled temperature ramps are investigated, and the results show a complex dependence. High...

Predicting trapezoidal and rectangular side weirs discharge coefficient using machine learning methods

Side weirs are useful and common devices in flow measurement issues. These weirs have been extensively used in hydraulic and environmental engineering applications. The characteristic of flow over side weirs are completely different from that over a weir normal to the approach channel. An accurate flow modeling over a side weir mainly depends on the proper estimation of discharge coefficient. In this study, the potential of two different machine learning methods, namely support vector machines combined with genetic algorithm (SVM–GA) and gene expression programming (GEP) were evaluated for predicting trapezoidal and rectangular sharp-crested side weirs discharge coefficient. Correlation coefficient (R), mean normalize error (MNE), and Nash–Sutcliffe index (NS) statistics are used for the evaluation of the model’s performances. The results showed that the SVM–GA model with R = 0.97, NS = 0.94, and MNE = 13% for trapezoidal side weir and R = 0.97, NS = 0.91, and MNE = 18% for rectangular side weir, in test period gives more accurate results than GEP. The results verify that the SVM–GA model can process used data series by better generalization ability and higher prediction accuracy.

Modeling fracture propagation and cleanup for dry nanoparticle-stabilized-foam fracturing fluids

Nanoparticle (NP)-stabilized foams can be generated at extreme water-deficient conditions (with quality as high as 95–99%) and yet with apparent viscosities >100cP. This makes them greatly appealing for hydraulic fracturing applications, where minimal water consumption and leak-off to the reservoir are desired. Initial assessment of propensities of these novel fluids for fracturing applications requires field scale simulations. However, conventional fracturing models are difficult to employ because they do not consider true foam hydrodynamics. We have developed a mathematical model to simulate the transport of NP-stabilized foams for hydraulic fracturing. The model combines fluid transport in reservoir matrix and fracture with rock mechanics equations and thus allows for considering the effects of foam on fracture dynamics. Gas and water flow with mechanistic accounting of foam generation and coalescence are simulated using population balance models. Transport of nanoparticles through porous media was simulated using single site filtration model. The equations are discretized using finite-difference scheme. Settari’s approach is used to embed fracture’s moving boundary with the matrix to accordingly update transmissibility. Model’s capabilities are verified with examples on fracture growth and fracture clean up processes to illustrate the benefits of using the NP-stabilized high quality foams. Fracture propagation was simulated for water, a conventional viscous fracpad and NP-stabilized foams of different qualities and textures. The simulations confirmed that larger foam viscosity generated wider fractures with smaller fracture half-length. In addition, fracture cleanup simulations show that fracturing fluid cleanup for foam based fracturing fluids could take the order of 10 days as opposed to that of viscous fracpad which could take up to 1000 days; demonstrating the advantage of using dry foams.

Solute Diffusion in Bentonite Pastes

AbstractSodium bentonite (Na-bentonite) is a high-swelling clay with low hydraulic conductivity (k) that is commonly used for hydraulic and chemical containment applications (e.g., engineered barriers, seals, and grouts) to limit advective (hydraulic) flow and chemical transport. In Na-bentonite pastes and other paste-like substances (e.g., high slump backfills, filter cakes, well seals, and slurried mine tailings) that exhibit low values of k (<10−9 m/s), diffusion can be a significant chemical transport process such that measurement of diffusion properties of these materials may be necessary. Based on these considerations, diffusion of NaCl from Na-bentonite pastes with porosities ranging from 0.96 to 0.98 was evaluated by adapting standardized test methods for diffusive leaching of contaminants from stabilized/solidified waste to a dialysis procedure commonly used for clay purification. The apparent diffusion coefficients (Da) measured with the proposed dialysis-leaching test method ranged from 2.26×1...

Approximate mechanical behavior analysis of a thick-wall metallic liner reinforced with composites, submitted to internal pressure

Abstract This study aims to simulate and to analyze the elastic and the damage behavior of a reinforced metallic liner (RML) by means of a computational tool, in order to aid in the design of high specific-stiffness and -strength barrels for heavy-duty hydraulic applications. Case studies for the program validation are undertaken using an AISI 1026 or St52.3 steel tubing reinforced with a polymeric composite of glass fiber and epoxy resin, wound in a hoop pattern. The mechanical behavior of the RML under internal pressure with no-end effects is predicted by means of strain measurements at the outermost layer. The mathematical model is based on the Classical Lamination Theory (CLT) improved with kinematic relationships that allow to introduce curvature effects. Numerical results based on experimental measurements show that the reinforcement is effective, allowing to considerably augment the maximum bearable pressure with respect to a non-reinforced metallic liner (nRML), without important weight or cost increase.