Hydraulic Design Optimization Research Articles

Study on the characteristics of fluid exciting force on impeller of high-speed centrifugal pump under the condition of poiseuille inflow

Abstract The paper adopted the turbulence model of Wall-Model Large Eddy Simulation with improved algebraic form (WMLES S-Omega) to carry out the study on the fluid exciting force on impeller of high-speed centrifugal pump under the conditions of Poiseuille inflow and uniform inflow. The external characteristics and the vibration displacement of the shaft of high-speed centrifugal pump are tested. The results indicated that it is the high matching that the test and numerical external data of high-speed centrifugal pump under the condition of Poiseuille inflow. The test results of vibration displacement of shaft match the fluid exciting force better in terms of waveform and phase difference under the condition of Poiseuille inflow. The contribution degree of force and torque from the shroud inner surface in the X and Y direction is 76.3%, 80.7%, 79.5% and 85% of the resultant force and torque, and its force from the inner and outer surfaces of shroud and hub in the Z direction is 94.3%, and its torque from blades’ surfaces in the Z direction is 98.3%. The study results can provide some theoretical support for the research of fluid exciting force and hydraulic optimization design of centrifugal pump.

Influence of axial distance between impeller and diffuser on the hydraulic performance and flow loss characteristics of bulb tubular pump

Abstract Bulb tubular pumps used in regional water transfer projects consume substantial power. Optimizing the geometric parameters of tubular pumps is crucial for enhancing efficiency and minimizing hydraulic losses. ANSYS CFX is used to investigate the axial distance between the impeller and the diffuser on the hydraulic performance and flow loss characteristics of the rear-bulb tubular pump, and the numerical simulation results are compared with the experimental data. Then, the entropy production theory is introduced to analyze flow losses. As the axial distance increases, the diffuser’s rectification effect on the flow at the impeller outlet deteriorates, leading to increased flow losses and decreased head and efficiency of the device. Flow losses in the bulb tubular pump are ranked from largest to smallest as follows: impeller, outflow channel, diffuser, inlet channel. The impeller exhibits the highest entropy production ratio, reaching 61.05% at an axial distance of 25 mm. By elucidating the energy loss distribution of each component under varying axial distances, this paper offers insights for the hydraulic optimization design of bulb tubular pumps.

Towards Hydraulic Design Optimization of Shaft Hydropower Plants: A 3D-CFD Application Based on Physical Models

The shaft hydropower plant (SHPP) is a novel hydraulic concept for low-head hydropower sites with several environmental and operational advantages over conventional layouts. However, the first two projects implementing this concept have shown comparatively high construction costs and project risks. Therefore, further optimization is required to increase economic attractiveness and enable broader market adoption. Initial model tests recommend a square-shaped shaft inlet with a three-sided approach flow for low-loss and fish-friendly inflow conditions. Yet, this design requires significant space for structural implementation and may be unsuitable for use with multiple shafts or as an extension of non-powered dams and weirs. This research paper presents the application of a computational fluid dynamics simulation setup to evaluate the hydraulic performance of various design configurations, especially alternative design layouts with a one-sided approach flow without further physical model tests. The simulation setup is calibrated against observations including head loss and velocity measurements from the physical model tests, and its satisfactory performance enables the analysis of alternative design layouts. This study aims to derive the most significant design parameters for achieving the desired hydraulic conditions at the intake. Increasing the flow depth before the intake and enlarging the inlet area have the most significant impact, while increasing the overflow of the front gate has the least significant effect. The chosen CFD application is deemed suitable for hydraulic design optimization and provides guidance on the key parameters to focus on for tailored site-specific design development.

Research on influence of wear ring clearance on energy loss of reactor coolant pump

Reactor coolant pump (RCP), the only rotating equipment in the nuclear island, directly determines the safety of the nuclear power system, has been likened to the “heart” of a nuclear power plant. The RCP needs to have very high reliability and stability. Its independent design and construction have always been the focus and difficulty of promoting the independent construction of nuclear power. To study the effect of the wear ring clearance on the energy loss characteristics of the RCP, the numerical simulation of the internal flow field of computation models with different wear ring clearance dimensions were conducted. The results indicate: As the wear ring clearance increases, the trend of performance reduction becomes more significant, especially under the large flow conditions; The increase of the wear ring clearance results in an increase of the pressure loss in the impeller and diffuser, and the variation in pressure distribution in different flow passages under different wear ring clearance dimensions is influenced by the position of the blade; The distribution of turbulent dissipation entropy production rate corresponds significantly to the distribution of direct dissipation entropy production rate, and the dissipation entropy production being more significantly affected by the wear ring clearance dimension closer to the shroud; The change of wear ring clearance dimension has limited impact on the wall shear stress entropy production of the impeller blade, while its effect on the diffuser blade is more pronounced; With the increase of the wear ring clearance, the scale of vortices near the impeller front shroud significantly increases, and the entropy production on the surface of vortex core at the impeller inlet gradually increases. This study is of great significance to ensure the secure and stable operation of the RCP, and provides an important reference for the hydraulic optimization design of the RCP.

Optimal hydraulic design of barrage considering the challenges of the presence of collapsible soil

Optimal hydraulic design of barrage considering the challenges of the presence of collapsible soil

Study on the influence of guide vane - blade number matching relationship (20-9) on the phase resonance risk coefficient of pumped storage units

Abstract In this paper, 19 pumped storage units put into operation or under construction in China (the matching relationship between the number of guide vanes and blades is 20-9, and the rated output of a single unit is not less than 200MW) were taken as the research object. Considering the risk of phase resonance caused by pressure wave propagation in the spiral casing of the unit, the phase resonance risk coefficients of units with different rotational speeds were analyzed. The concept of perimeter equivalent coefficient was proposed, and the design criteria for controlling the phase resonance risk coefficient within 25% was obtained, which provided references for optimal hydraulic design of pumped storage units.

Study on phase resonance risk coefficient of pumped-storage units

Abstract In this paper, 48 pumped-storage units (rated output of a single unit is not less than 100MW) put into operation or under construction in China were taken as the research object, and the risk of phase resonance caused by pressure wave propagation in the spiral casing of the unit was studied. The risk coefficient of phase resonance under the matching relationship between different rotational speeds and the number of guide vanes and blades was analyzed, and the advantages and disadvantages of the matching relationship between different rotational speeds and the number of guide vanes and blades were compared. The fitting formulas of the circumferential Mach number with rated head due to the pressure wave propagating along the spiral casing under two equivalent diameters were proposed, which provided references for the optimal hydraulic design of pumped-storage units.

Research on hydraulic optimization design method of water-jet propulsion pump considering hump index

Research on hydraulic optimization design method of water-jet propulsion pump considering hump index

Performance Envelope of a 538-Series High-Speed Helico-Axial Pump for High-Gas-Volume-Fraction Operation

Summary Operating at high speeds can have the benefit of increasing the capability of pumps to enhance surface or downhole production of fluids with high gas volume fraction (GVF). This study presents the performance envelope of a high-speed helico-axial pump (HAP) operating at high GVFs (>80%). The ultimate aim of the physical tests was to ascertain the operating capabilities of the pump for potential scaleup to a field prototype. The HAP housing outer diameter was 5.38 in. and operated at a rotational speed of 6,000 rev/min. Air and water were the test fluids, with an average pump intake and a discharge temperature of 28°C. The fluid volume flow rates were varied while maintaining 46 psig at the HAP intake. The liquid and total intake volume flow rates varied from 128 B/D to 664 B/D and 4,941 B/D to 7,593 B/D, respectively. The corresponding dimensionless pressure boost (DPB), GVF, liquid flow coefficients (LFCs), and total flow coefficients (TFCs) were recorded. Additional parameters noted were the percentage of electric current draw to full-load motor current by the HAP motor and the percentage of electric power input to full load power to the HAP motor. The results showed that the HAP had a stable operation during the tests for intake GVF range of 91–98%. The corresponding pump DPB was in the range of 0.0138–0.0751. These values being positive indicated the capability of the HAP to boost fluid pressure even for such high intake gas content and avoid pump gas lock. The results also showed that for a given intake GVF, the HAP DPB increased with decreasing LFC. For a given LFC, the DPB decreased with increasing intake GVF. The percent electric input power to the HAP motor varied between 28% and 64% of full-load motor power. It was observed to strongly increase with decreasing LFC at a given intake GVF and very strongly decrease with increasing intake GVF at a given LFC. The associated percent electric current draw by the HAP motor was seen to vary between 24% and 53% of full-load motor current. Its variation with LFC and intake GVF was similar to those of the percent electric power input. The DPB, percent electric current, and power draw by the HAP motor variations with TFC for a given intake GVF were similar to those of the LFCs. In conclusion, the HAP demonstrated the capability to boost fluid pressure when handling high GVF flows. It is being scaled up to a field prototype to handle higher volume flow rates of high GVF gas-liquid mixtures. This study mainly highlights the method to extend the gas-handling capability of a HAP by operating it at high speeds. Optimal hydraulic design and proper conditioning of the inlet flow components were also incorporated into the HAP architecture. Expanding the HAP operating envelope to handle high-GVF flows significantly unlocks the potential for field operators to maximize hydrocarbon production from high-gas content applications. This, in turn, increases the economic bottom line from the field asset.

Study on Impeller Optimization and Operation Method of Variable Speed Centrifugal Pump with Large Flow and Wide Head Variation

The benefits of variable speed centrifugal pumps include high stability, a broad operating range, and adjustable input power. In water distribution systems, the pump units are increasingly using variable speed technology. The energy-saving features and operational stability of the pump station are directly impacted by the hydraulic performance and the operation strategy. In this study, CFD numerical analysis and model tests were adopted to design and evaluate the hydraulic performance of the variable speed centrifugal pump with large flow and wide head variation in Liyuzhou Pump Station. Under the premise of ensuring the wide head variation, the optimized centrifugal pump met the requirements of hump margin and efficiency in the high head zone and the cavitation margin in the low head zone. The test results demonstrated that the operational range of the variable speed centrifugal pump was successfully widened by reasonable hydraulic parameters selection and impeller optimization. The safe and efficient operational range of the variable speed unit was determined by means of taking the performance requirements of the pump’s maximum input shaft power, cavitation characteristics and pressure fluctuation into consideration. The scientific and reasonable operational path to meet the various operation needs was also investigated and determined for the pump station’s actual operation needs. A high efficiency, safe operation, and a simplified control logic were achieved by using the operational path, which makes it a reasonable potential guide for hydraulic design and operational optimization of variable speed centrifugal pumps with large flow and wide head range.

Analysis of Pressure Pulsation and Structural Characteristics of Vertical Shaft Cross-Flow Pumps

In order to study the pressure pulsation characteristics and structural dynamic response characteristics of a vertical shaft cross-flow pump, this study used a computational fluid dynamics (CFD) numerical simulation method to analyze the pressure pulsation characteristics of the inlet passage, impeller, and guide vane positions of the vertical shaft cross-flow pump device. At the same time, this study analyzed the equivalent stress–strain characteristics of the impeller and guide vane of a vertical shaft cross-flow pump based on fluid structure coupling technology and comprehensively analyzed the deformation modes of the impeller blades and guide vanes under dynamic water flow. This research shows that due to the influence of rotor–stator interaction, the amplitude of pressure pulsation at the interface between the impeller and guide vane of the pump device is the largest and that the main frequency distribution at this position is relatively complex. The non-uniformity of stress distribution at the impeller position gradually decreases with an increase in the radial distance. The high stress and strain zones of the impeller and guide vane are concentrated at the root of the blade. This study can provide reference for hydraulic optimization design and stable operation of similar pump devices.

Preparation of geomechanical rock properties library for reservoir optimization of hydraulic fracturing design at the sites of JSC Samotlorneftegaz

Preparation of geomechanical rock properties library for reservoir optimization of hydraulic fracturing design at the sites of JSC Samotlorneftegaz

Optimization of hydraulic design of approach channel of spillway by hydraulic model studies

The approach channel is intended to divert the flow safely from its original course and the diversion may be intended towards spillway, power intake or any other hydraulic structure. The hydraulic design of the approach channel involves determining cross-section dimensions of the channel for the design flood at a given flow velocity, slope and shape or alternatively determining the discharge capacity for the given layout and cross-section dimensions. Proper alignment of approach channel minimizes the head loss by reducing the oblique flows. Sometimes, the spillway approach channel is submerged with unconfined boundaries, asymmetrical in layout. However, these conditions are site-specific. Hydraulic model studies play a substantial role in testing these kinds of layouts to find out an optimum layout. Studies have been carried out on a 1:140 scale model of the spillway to optimize the layout of an unconfined, unlined, asymmetrical, and submerged approach channel by the assessment of velocity profiles and flow pattern in the approach channel for different shaped layouts. Studies indicated that the efficient layout of the approach channel is governed by its maximum available width and straightforward approach, prevention of lateral inflows by the provision of additional embankments and provision of suitable length of the guide bund.

Thermal hydraulic design and mass optimization of a 100-kWe S-CO2 cooled Mars-surface fission reactor system

Fission reactor with electrical power of 100 kW to megawatt is a promising power option for upcoming deep space exploration. To reduce the number of space launches and the costs, it is necessary to design an energy supply system coupling fission reactor with energy conversion system of high efficiency and compactness. The combination of gas-cooled fast reactor and supercritical carbon dioxide (S-CO2) Brayton cycle has the advantages of simple system layout, compact structure and high thermal efficiency.This paper aims to carry out researches on the thermal hydraulic design and mass optimization of 100kWe reactor system for Mars-surface application.An analysis code which includes thermodynamic models for different components in the system, as well as mass evaluation models for radiator, recuperator and reactor, is developed and validated to provide an analysis tool. An S-CO2 Brayton cycle directly cooled reactor system is proposed, which applies Tube-In-Duct fuel assembly to make up the core and heat pipe radiator as heat rejection system. The thermal hydraulic evaluation of the reactor core, thermodynamic performance evaluation as well as overall mass evaluation of the whole system are carried out to achieve an optimized 100kWe fission reactor system for Mars surface with minimum mass. The optimal design has an operating pressure of 16 MPa, core outlet temperature of 600 °C, radiator panel area of 120 m2 and an overall mass of 1862.98 kg considering the reactor and key components of Brayton cycle. S-CO2 Brayton cycle directly cooled reactor system has a comparable specific mass as He-Xe cooled reactor with lower operating temperature, which is beneficial for material selection and provides another option for space reactor development.

Hydraulic design optimization of spherical header for future fast reactors of India

The liquid sodium as coolant in a typical pool type Liquid Metal cooled Fast Breeder Reactor (LMFBR), flows through primary sodium pump, spherical header and finally enters the grid plate, which acts as an inlet plenum to heat-generating sub-assemblies. The reduction of pressure drop in primary circuit would reduce the operating cost of the system. Spherical header, a vital component in primary circuit suffers major flow non-uniformities resulting in higher pressure drop. Reduction of the pressure drop by uniformization of sodium flow in spherical header is considered. To this end, a 3D computational fluid dynamics (CFD) analysis is carried out to investigate the hydrodynamics of flow, inside the spherical header. Towards this a relationship between pressure loss coefficient and geometrical dimensions, viz., diameter and height of the cone, inside the header are established in order to minimize the pressure drop. The variation of pressure loss coefficient is estimated for header without and with the internals. The static pressure loss coefficient inside the spherical header without an internal cone is found to be 5.59. With a suitable and optimized geometrical dimension of the cone as internal flow guiding device, the loss coefficient is reduced to 0.53. The loss coefficient predicted for the spherical header is validated against the experimental estimates. Consequently, the simplified design of the flow guiding device is achieved by removing baffles.

Optimum hydraulic design of cut-off under hydraulic structures using the simulation–optimization method

Optimum hydraulic design of cut-off under hydraulic structures using the simulation–optimization method

Hydraulic optimization design of centrifugal pumps aiming at low vibration noise

In order to reduce the vibration noise generated by the centrifugal pump in the working process and improve the working efficiency of the centrifugal pump, the sound field numerical calculation of IS80-65-160 single-stage single-suction centrifugal pump was carried out. Under the condition that the parameters of the pump body and the impeller remain unchanged, the number of blades of the prototype pump impeller was designed as 4, 5, 6, and 7, respectively. The flow-induced vibration and noise characteristics of centrifugal pumps were studied from two aspects of numerical simulation and test, and the renormalization group k-ε model was used to simulate the steady and unsteady state of centrifugal pumps with different blade numbers. The external characteristics, pressure pulsation characteristics, vibration, and noise of the centrifugal pump were obtained, and the flow-induced vibration and noise test platform of the centrifugal pump was built for experimental verification. The research showed that the flow induction in the model pump was the main factor affecting the vibration of the prototype pump, and the shaft frequency and blade frequency were the main reasons causing the noise of the prototype pump. The vibration of each blade was the most concentrated at onefold blade frequency, and the peak of the sound field acoustic pressure level of the pump body was higher than other frequencies at threefold blade frequency, which was most obvious in the tongue region of the volute. With the increase of blades, the noise in volute decreased. The vibration intensity of the 4-blade prototype pump was lower, but the efficiency and head were also lower. The vibration intensity of the 5-blade prototype pump was the highest, the comprehensive performance of the 6-blade prototype pump was better, and the vibration of the 7-blade prototype pump was unstable. The test results showed that six blades could effectively reduce the flow-induced vibration noise of centrifugal pumps and improve the working environment, which provided certain application value and guiding significance for the hydraulic design of the subsequent low-noise centrifugal pumps.

Experiment and Numerical Simulation on Hydraulic Loss and Flow Pattern of Low Hump Outlet Conduit with Different Inlet Water Rotation Speeds

The rotation speed of water at the inlet of the low hump outlet conduit has a great effect on its hydraulic performance. Therefore, the influence of different inlet water rotation speeds on hydraulic loss and flow pattern of low hump outlet conduit is studied in this paper. By solving RANS equations and the RNG k-ε turbulence model, the hydraulic loss and 3D flow field of the low hump outlet conduit were calculated under different inlet water rotation speeds. To verify the numerical results, the model tests of low hump outlet conduit with different guide vanes were conducted. The results show that along with the growth of inlet water rotation speed, the hydraulic loss of outlet conduit will firstly decrease by degrees and then increase dramatically, the vortex location moves from the whole bottom of the descent segment to the right bottom of descent segment and the vortex area becomes smaller, the flow pattern of the whole conduit is improved obviously. The hydraulic loss and flow field of numerical simulation are consistent with those of the model test. Because of its great influence on hydraulic performance, inlet water rotation speed must be taken into consideration in the hydraulic optimization design of guide vane and low hump outlet conduit.

Experimental investigation on the shale's time-dependent microphysical characteristics under the fluid-shale interaction

The long-term fracturing process will affect the shale's microphysical characteristics. In this paper, under the fluid-shale interaction with different duration, the evolutions of shale's minerals, pore structure, brittleness, as well as the ions of fluids are investigated. The results show that, as the interaction proceeding, the shale's typical minerals experienced a resolution and regeneration process, while the ions concentration of the fracturing fluid shows negatively correlated with the that of minerals correspondingly. The evolutions of shale's pore volume and the specific surface area show opposite changing trends, which indicates that time-dependent micropore is characterized as dissolution first and then filling. Finally, the shale's time-dependent brittleness model is developed based on the minerals' evolution. These findings will provide a new insight for the optimization of hydraulic fracturing design based on shale's dynamic microphysical characteristics.

Inverse Design and Optimization of Low Specific Speed Centrifugal Pump Blade Based on Adaptive POD Hybrid Model

To improve the prediction accuracy of the surrogate model and reduce the calculation cost for hydraulic optimization design of centrifugal pump impeller, an inverse design and optimization method based on adaptive proper orthogonal decomposition (APOD) hybrid model was proposed. Initial samples were designed by perturbing blade control parameters of the original model. The samples were classified using the K-means clustering algorithm, and the adaptive samples were selected according to the category of the objective sample. The snapshot set is composed of blade shape parameters and the CFD flow field data in impeller, which is decomposed into a linear combination of orthogonal bases by the proper orthogonal decomposition (POD) method to predict the objective parameters. According to the objective load distribution, the low specific speed centrifugal pump was inversely designed by using the APOD model, and its initial blade was obtained. And then, the flow field corresponding to disturbed blade shape was predicted using the APOD method, so as to evaluate the gradient of the objective function to design variables. Finally, the initial blade was optimized by the gradient descent method. The results show that the APOD hybrid model method can be employed to accomplish the blade inverse design and the flow field prediction in the optimization design of centrifugal impeller, which significantly reduces the numerical calculation cost and improves the accuracy of the flow field prediction.