Number Of Blades Research Articles

The Design and Application of a Vectored Thruster for a Negative Lift-Shaped AUV

Autonomous underwater vehicles (AUVs), as primary platforms, have significantly contributed to underwater surveys in scientific and military fields. Enhancing the maneuverability of autonomous underwater vehicles is crucial to their development. This study presents a novel vectored thruster and an optimized blade design approach to meet the design requirements of a specially shaped AUV. Determining the ideal blade characteristics involves selecting a maximum diameter of 0.18 m and configuring the number of blades to be four. Furthermore, the blades of the AUV were set to rotate at a speed of 1400 revolutions per minute (RPM). The kinematics of the thrust-vectoring mechanism was theoretically analyzed. A propulsive force test of the vectored thruster with ductless and ducted propellers was performed to evaluate its performance. A ductless propeller without an annular wing had a higher propulsive efficiency with a maximum thrust of 115 N. Open-loop control was applied to an AUV in a water tank, exhibiting a maximum velocity of 0.98 m/s and a pitch angle of 53°. The maximum rate of heading angle was 14.26°/s. The test results demonstrate that the specially designed thrust-vectoring mechanism notably enhances the effectiveness of AUVs at low forward speeds. In addition, tests conducted in offshore waters for depth and heading control validated the vectored thruster’s capability to fulfill the AUV’s motion control requirements.

Transient Flow-Induced Stress Investigation on a Prototype Reversible Pump–Turbine Runner

Pump–turbine units with high heads are subjected to strong pressure pulsations from the unsteady transient flow in fluid channels, which can produce severe vibrations and high stresses on the pump–turbine structural components. Therefore, reducing transient flow-induced stresses on prototype reversible pump–turbine units is an important measure for ensuring their safe and efficient operation. A high-head prototype reversible pump–turbine with a rated head of 440 m was used to investigate the transient flow characteristics and the flow-induced-stresses in this study. First, the flow passages of the pump–turbine unit and the structure of the reversible pump–turbine runner were constructed with CAD tools. Next, CFD simulations at the full load were performed to investigate the pressure pulsation characteristics of the pump turbine in both the time domain and the frequency domain. After this, the pressure files calculated by the CFD were exported and applied to a finite element model of the pump–turbine runner to calculate the transient flow-induced dynamic stresses. The results show that the pressure pulsations in the flow passage are closely related to the rotational speed, the guide vane number, and the runner blade number of the pump–turbine unit. The maximum flow-induced stresses on the pump–turbine runner at the full load were below 2 MPa and lower than the allowable value, which reveals that the designs of the pump–turbine runner and the flow passage are acceptable. The conclusions can be used as a reference to evaluate the design of high-head pump–turbines units. The approaches used to carry out the transient flow-induced stress calculations can be applied not only to pump–turbines units but also to other types of fluid turbomachinery such as pumps, turbines, fans, compressors, turbochargers, etc.

Experimental Analysis of a Vertical Wind Turbine using Plastic Blades

It had presented for current investigation the powered performance of H vertical wind turbines for wind speed of (1, 2, 3, 4, 5, 6, 7, 8) m/s region in Al-Mussaib city-Iraq, located at 3205' North latitude and 4403' East longitude. The Experimental test rig includes H vertical wind turbine which configured and made-up in order to analyze the effect of different ambient and wind speed variable conditions on the powered performance of H typre vertical wind turbine which consists of blades which are made from plastics. The turbine blades are designed from plastic strips with a thickness of 3 mm, each part is along 50 cm in diameter, 16 cm in diameter, and the number of blades used in this experiment is six blades to form required turbine. The experiments were tested outdoor at Technical College in AL-Mussaib city-Babylon-Iraq for a period of March and April 2022. The results showed that the power output, with wind speed of minimum value 1 m/s generate 5 Watts, while with wind speed of maximum value 7 m/s generate 100 Watts. Also, the power output, with turbine rotational speed of minimum value 100 rpm generate 8 Watts, while with turbine rotational speed of maximum value 1000 rpm generate 120 Watts. Moreover, the power output, with turbine elevation of minimum value 7 m generate 100 Watts, while with turbine elevation of maximum value 21 m generate 250 Watts.

Numerical study on effects of geometric parameters influence on two-dimensional cycloidal propellers

Aiming to investigate different geometric parameters on cycloidal propellers' hydrodynamic characteristics, an efficient two-dimensional (2D) cycloidal propeller model was established. The Reynolds-averaged-Navier-Stokes (RANS) solver was used to simulated the open water maneuverability of the cycloidal propellers' in fully azimuth angle. Hydrodynamic characteristics under different geometric parameters were analyzed in detail. The geometric parameters are blade number, chord length, thickness and camber, respectively. The research shows that with the increase of the blade number, the side thrust increases, and main thrust decreases. The longer of the blade chord length, the greater the thrust. As the blade camber increases, the effective thrust increases. Additionally, the blade thickness has little effect on side thrust, but it can improve the utilization of torque and significantly increase the efficiency of the propeller. The revealed findings in present paper should contribute to cycloidal propellers' preliminary design.

Precise acoustic drone localization and tracking via drone noise: Steered response power - phase transform around harmonics

This study introduces a new method for precise acoustic drone localization and tracking via the noise generated by the drone. Drone noises include harmonic frequency components which are related to the rotational speed of the propeller and the number of blades. This study integrates utilization of the frequency components around harmonics into Steered Response Power - Phase Transform (SRP-PHAT). First, a custom discrete Fourier transform (namely DFT-Harmonics) is defined which concentrates only on the vicinities of harmonics to capture the frequency components possibly related to the drone sound. Then, DFT-Harmonics is integrated into SRP-PHAT, which is named SRP-Harmonics. The benefits of SRP-Harmonics are explained and illustrated via SRP maps and videos. Experiments with real microphone array data show that SRP-Harmonics is precise in localizing and tracking a drone, while the ordinary SRP-PHAT can not be reasonably successful. Moreover, SRP-Harmonics after Kaiser window can maintain its performance even when significant level of artificial white noise or natural wind noise exists in the data.

Evaluating PDC bit-rock interaction models to investigate torsional vibrations in geothermal drilling

Polycrystalline diamond compact (PDC) bits are superior for drilling geothermal wells because of their superior drilling performance compared to conventional roller cone bits. However, the shear action of PDC bits generates detrimental vibrations during drilling. The main objective of this study was to establish a methodology to analyze and predict the stick-slip severity in hard rocks for geothermal wells. Two non-linear coupled axial-torsional bit-rock interaction (BRI) models are presented: one is based on a velocity-decaying friction model (VDF), and the other is based on a state-dependent delay friction model (SDDF). The capabilities of the two models were evaluated to assess the axial and torsional dynamic stabilities of drill stems in deep geothermal wells. The comparative analysis, along with the results from both models, were validated using geothermal well downhole data. Five distinct zones were selected for analysis, and the stick-slip severity value (SSV) was calculated using these two models (VDF and SDDF). The results from these two models for the five different zones were compared with the field data. The results indicated that VDF demonstrated superior quality when compared with field values, as the results of VDF were within the interquartile range of the observed SSV in each zone. A sensitivity analysis employing spider plots was performed for both models, considering parameters related to rock, bit, operational, and frictional aspects. In terms of the operational parameters, the weight-on-bit (WOB) and revolutions per minute (RPM) exerted the most significant influence on the SSV for both models. For the VDF model, the sensitivity analysis indicated that the frictional parameter, uniaxial compressive strength (UCS), and number of cutters (NOC) had the most pronounced impact on the SSV. In the case of the SDDF, the Intrinsic specific energy (ISE), bit diameter, and number of blades (NOB) are the key factors that predominantly affect the SSV.

Indonesia's Breakthrough in Maximizing Wind Energy Efficiency Through Optimized Blade Configuration

Indonesia faces rising energy demand, risking an energy crisis and increased fossil fuel dependence. This study explores using NACA 0021 airfoil blades to improve wind turbine performance by analyzing the effect of different rotor blade numbers. Conducted at Universitas Muhammadiyah Sidoarjo, the research tested turbines with 2, 3, and 4 blades, measuring current, voltage, power, and efficiency. Results showed that more rotor blades enhance turbine performance, increasing current and voltage output. This suggests optimizing blade configurations can significantly boost small-scale wind energy systems, helping reduce fossil fuel reliance and mitigate the energy crisis. Highlights: 1. More rotor blades boost turbine performance: increased current and voltage.2. NACA 0021 airfoil optimizes small-scale power generation.3. Effective blade configuration reduces fossil fuel reliance, mitigating energy crises. Keywords: wind energy, NACA 0021, rotor blades, turbine performance, renewable energy

Research on the design of hydraulic heater and optimization of energy matching of internal combustion engine heated steam generator

A novel internal combustion engine heated steam generator (ICEHSG) and the energy-matching optimization method are proposed in this paper. In the ICEHSG, the energy generated by the internal combustion engine (ICE) of the vehicle is converted to thermal energy as the heating source of the steam generator. Firstly, the prototype model of the hydraulic heater (HH) of the ICEHSG is established, and the relevant structural parameters are optimized based on computational fluid dynamics (CFD). Secondly, the energy matching between HH and ICE is optimized based on the particle swarm algorithm with compression factors (CFPSO). Finally, the energy provided by the ICEHSG and the required energy of the steam generation process is optimized, and the analysis is combined with the actual engineering case. The simulation results show that when the inclination angle of the blade is 45°, the number of rotor and stator blades is 31–33, and the diameter of the circular circle is 386 mm, the torque performance and heating performance of the HH are optimal. Meanwhile, the maximum thermal power can be obtained when the liquid filling rate of the HH is 100%. After optimization, the maximum torque of the HH working with the ICE is increased by 8.07%. Compared with the traditional boiler steam generator, the ICEHSG system proposed in this paper can increase the thermal efficiency by 1.3%–2.7% and reduce the cost by 37%.

Optimization of Centrifugal Pump Impeller Based on Neural Network and NSGA-II Algorithm

Abstract This article focuses on the multistage centrifugal pump secondary impeller as the research object, and the two performance parameters of head and efficiency are taken as the optimization objectives. Firstly, the range analysis of significant influence degree of impeller geometric parameters was carried out by partial factor test method. The blade inlet angle at the front and rear cover boards of the impeller, blade outlet angle and blade wrap angle as the optimization variables, two optimization schemes with different blade numbers were proposed. On this basis, the optimal Latin hypercube sampling method was used to extract samples from the two schemes, CFD technology was used to calculate the corresponding target value of each sample, BP neural networks with different structures were used to train the samples, and the agent model with the highest prediction accuracy was optimized as the population evaluation function of NSGA-II algorithm to search for optimization. The results show that the pump performance parameters have been improved after optimization of Scheme II, and the flow of the internal flow field conforms to the law. Finally, through the experimental verification, the optimized centrifugal pump head and efficiency increased by 3.21m and 3.05%.

Analysis of pressure pulsation in a multi-stage double suction centrifugal pump

Abstract Pressure pulsation is a common phenomenon, which results from different causes. The intenser pressure pulsation occurs in the pump, the severer the damage to the pump. In the paper, with the assistance of detached eddy simulation method, the characteristic of pressure pulsation in the multi-stage double suction centrifugal pump is studied to understanding the internal flow circumstance. The results reveal that the pressure pulsation intensity reaches the maximum at blade trailing edge, which propagates to the tongue region of forward flow channel and double-volute under the low rates. Furthermore, it can be concluded that the pressure pulsation of region with obvious rotor–stator interaction between rotating impeller and stationary volute is generally larger at low flow rates. The pressure pulsation near the suction side of blade trailing edge shows the feature of broadband frequency and with increasing flow rate the bandwidth of broadband decreases drops rapidly except BP1. Due to the influence of the number of impeller blades, the dominant frequency of monitoring points in the inter-stage flow channel and the volute is basically located at a frequency that is twice the blade frequency. Meanwhile, because of the symmetry of the geometric structure of the reverse flow channel, the pressure pulsation curve changes of its internal monitoring points are similar under the same flow rate.

Influence of impeller energy dissipation characteristics of multi-blade axial flow pump impeller by the cascade density

Abstract This paper investigates the influence of cascade density on energy dissipation in the impeller of a multi-blade axial-flow pump. Three-dimensional transient numerical simulations were conducted using the SST k-ω turbulence model for impeller schemes with different cascade density, corresponding to different blade chord length and pitch. Entropy production theory was applied to locate the regions with high energy loss in the impeller. The relationships between local entropy generation, energy loss, and unsteady flow were analyzed for different cascade density. The results indicate that impeller entropy output of the multi-blade axial-flow pump is highly consistent with the head loss during testing. Turbulence dissipation accounts for more than 50% of the total energy loss, followed by wall friction, while direct dissipation is the smallest contributor. The relative loss of the impeller can be minimized by decreasing the number of blades or increasing the blade chord length. By comparing energy dissipation in blade rotation with different chord length and pitch, it is found that turbulent dissipation ability can be controlled more effectively by changing chord length, while the ability of direct dissipation can be controlled more effectively by changing the pitch.

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.

Numerical study on the flow-induced vibration of a high-pressure-jet pump on a dredger and corresponding impeller optimization

Abstract Trailing suction hopper dredgers are usually equipped with high-pressure-jet pumps, which provide high pressure water to improve dredging efficiency. In a newly built trailing suction hopper dredger, the high-pressure-jet pump encountered serious vibration problem. In this study, unsteady Reynolds-averaged Navier-Stokes equations were solved with Shear Stress Transport k-ω turbulence model to carry out pump-pipeline matching analysis, and the causes of flow-induced vibration were discussed. The impeller was correspondingly optimized by increasing the blade number and moderately decreasing the blade inlet setting angle and wrap angle. The optimization results show that the high-pressure-jet pump works in the high-efficiency zone both for the high-speed dredging process and low-speed hopper discharging process, and the time-average value and amplitude of the hydraulic radial force drops by more than 30% under the required working condition, which effectively mitigates the flow-induced vibration.

Analysis of influence of blade number on aerodynamic performance and noise of forward centrifugal fan

Analysis of influence of blade number on aerodynamic performance and noise of forward centrifugal fan

Effect of impeller structure on aerodynamic performance and noise reduction of a small multi-blade centrifugal fan

In this study, the numerical simulation and orthogonal test are combined to study the effects of blade outlet angle, blade inlet angle, and blade number on the centrifugal fan flow characteristics, stress distribution, and noise control. The experimental tests were carried out to confirm the accuracy of the computational model. The computational fluid dynamics (CFD) technology was used to establish 16 groups of impeller models and derive the optimal parameter combination form. The results show that the blade inlet angle and outlet angle have more significant effects on efficiency and flow rate of fans. Among different optimize structures, the A8 fan with an inlet angle of 60°, an outlet angle of 180°, and a blade number of 45, has the best aerodynamic performance, with a 17.4% increase in flow rate, a 3.3% increase in efficiency, a 7.6% reduction in noise and a 23.0% reduction in impeller stress, compared to the original fan. Reasonable adjustment of the inlet and outlet angles greatly improves fluid distribution and suppresses flow separation. Furthermore, the noise can be reduced by lessening the disturbance between the volute tongue and wake flow, so the flow state gets greatly improved at the volute tongue region.

Study on Evaluation and Prediction for Shale Gas PDC Bit in Luzhou Block Sichuan Based on BP Neural Network and Bit Structure

Deep and ultra-deep shale gas resources have great potential, but well drilling faces many challenges. The Polycrystalline Diamond Compact (PDC) bit has become the primary rock-breaking instrument for oil and gas drilling. Reasonable bit structure designs can promote rock-breaking efficiency and extend service life. In this study, reverse modeling technology is used to analyze the structural characteristics of PDC bits collected in the field, and the influence of the structural characteristics of the bit at a specific interval on the rate of penetration (ROP) and drill footage is investigated using the Spearman rank correlation coefficient method. The number of blades, cutting angle of the cutters, crown rotation radius, internal cone angle, and diameter of the cutters are discovered to be the main structural characteristics that affect the ROP and footage of the bits, and the degree of influence varies depending on the formation conditions. The number of blades, crown rotation radius, inner cone angle, and cutting angle of the cutters have a significant impact on the ROP, whereas blade thickness, gauge length, gauge width, nozzle equivalent diameter have a significant impact on the bit footage. In addition, a back propagation (BP) neural network is utilized to build a prediction model of bit footage and ROP over a certain interval based on the structural characteristics of the bit. The goodness of fit of the model is greater than 85%, and its accuracy is high. Based on the usage of the bit, the evaluation and prediction of the bit can provide a reference for the structural design and optimization of the bit in a specific interval, guide the bit selection work, rationally plan the drilling operation, and reduce the drilling cost.

Aerodynamic performance enhancement of centrifugal compressor using numerical techniques

Background Centrifugal compressors are dynamic machines utilizing a rotating impeller, efficiently accelerate incoming gases, transforming kinetic energy into pressure energy for compression. They serve a wide range of industries, including air conditioning, refrigeration, gas turbines, industrial processes, and applications such as air compression, gas transportation, and petrochemicals, demonstrating their versatility. Designing a centrifugal compressor poses challenges related to achieving high aerodynamic efficiency, surge and choke control, material selection, rotor dynamics, cavitation, erosion, and addressing environmental considerations while balancing costs. Optimizing maintenance, reliability, and energy efficiency are essential aspects of the design process. Methods The primary objective of this research is to comprehensively investigate and improve the aerodynamic performance of centrifugal compressors. To accomplish this, a comprehensive investigation of variables such as blade number and hub diameter, along with various turbulence models will be conducted. This approach will leverage numerical techniques to fill the significant gaps in the current literature regarding centrifugal compressor design and optimization. The study encompasses the evaluation of two turbulence models, namely Shear Stress Transport and K-epsilon. Furthermore, it delves into the fine-tuning of blade geometry, including variations in blade number and hub diameter, aiming to refine the design for optimal performance. Extensive analyses using Ansys CFX encompass key variables such as Pressure, Mach Number, Density, Velocity, Turbulence Kinetic Energy, and Temperature. Results Notably, the optimized pressure profile yielded remarkable results, achieving a substantial 36% improvement, demonstrating the tangible benefits of these design enhancements. Conclusion The outcomes of this research hold significant utility for engineers, manufacturers, and regulatory bodies, offering invaluable insights and guidance to enhance compressor performance and efficiency.

Mitigating Effect of Exogenous Melatonin on Salt and Drought Stress in Cyperus esculentus L. during the Tillering Stage

Drought and salt stress are important limiting factors that affect crop growth and yield. As a newly recognized plant hormone, melatonin can participate in the regulation of plant stress tolerance and enhance the tolerance of plants to adversity. In this study, the effects of melatonin (150 µmol·L−1) on agronomic traits, osmotic adjustment substances, antioxidant enzyme activities, and reactive oxygen species content in C. esculentus under different salt (0 and 200 mmol·L−1 NaCl), drought (70% field capacity, 50% field capacity), and salt–drought (200 mmol·L−1 NaCl + 50% field capacity) stress conditions were determined using a pot experiment. Spraying with 150 µmol·L−1 of melatonin effectively improved the plant height, number of blades, biomass, and root growth of C. esculentus seedlings under salt, drought, and combined stress. In addition, this treatment also increased the relative water content, superoxide dismutase, peroxidase, and catalase activities, and soluble sugar content of the blades and decreased the relative electroconductivity conductivity and proline, malondialdehyde, hydrogen peroxide, and superoxide anion contents. A comprehensive analysis showed that spraying the plants with exogenous melatonin could increase the activity of antioxidant enzymes and the accumulation of osmotic adjustment substances in C. esculentus blades under salt and drought stress, effectively remove excessive reactive oxygen species, alleviate oxidative damage, and enhance the ability of C. esculentus to resist salt and drought stress.

Design and optimization of a siphon turbine using the response surface methodology

A comprehensive examination of siphon turbine design and optimization using the response surface methodology (RSM) is presented in this study. The goal was to improve the turbine efficiency by analyzing the impact of two key factors: the number of blades (n) and the ratio between the hub diameter (d) and the outer diameter of the rotor (D), (d/D). The application of RSM facilitated the creation of a response surface, unveiling the optimal combination of factors for maximizing efficiency. The novelty of this article lies in utilizing the response surface methodology to refine the design of existing turbines, resulting in a more streamlined and effective design process tailored to the specific requirements of the installation. The findings indicated that rounding the number of blades to 5 and maintaining a constant d/D ratio of 0.35 yielded the highest efficiency (41.4%). Experimental validation was carried out and the accuracy of the optimized design was demonstrated, paving the way for practical applications in renewable energy solutions. Therefore, the effectiveness of RSM in optimizing siphon turbine designs is supported since valuable insights are provided for enhancing the energy efficiency in small-scale hydropower systems. The investigation contributes to the development of sustainable and clean energy technologies, showcasing the potential of siphon turbines in harnessing low-head water sources for power generation.

Numerical evaluation of low-head inverted cross-flow turbine design method: A comprehensive study

This study aimed to address the challenges of micro-hydropower generation in low-head environments to expand the proportion of hydropower in renewable energy and achieve a carbon neutrality policy. To achieve these goals, various factors affecting the micro-hydro systems, including geographical constraints, construction costs, and grid connectivity, were reviewed and assessed. The results concluded that a novel type of cross-flow turbine with inverted structures, improved the economic feasibility, productivity, and installability of micro-hydropower plants by reducing head losses in open channels or small streams. The parametric studies consisted of four steps: first, designing the initial inverted cross-flow turbine based on the traditional design rules; for the second and third steps, a parametric study for comparing the runner diameter ratio and the number of blades is conducted; and in the last step optimized turbine was designed. The best efficiency point of the optimized inverted cross-flow turbine was 72.92 % at a runner rotational speed of 170 RPM with a 0.75 runner diameter ratio and 35 blades. The optimized turbine was improved by 7.8 % in power and 7.35 % in efficiency, higher than the initial turbine. From the hill chart comparison between the initial and optimized turbine, operation range expansion was confirmed. Overall, this research demonstrates the potential of the inverted cross-flow turbine under low-head conditions.