The use of in-pipe water turbines for small-scale energy harvesting from pipe networks is starting to gain popularity. However, limited research have looked into whether adding helical blade turbines ...would be feasible with a spherical lift base in a water supply network. Three Naca airfoil (0012, 2412, 4412) were used to study the ratio of lift to drag force for each wing, Benefit from Qblade and ANSYS CFX software, and choosing the wing that has the highest ratio. The study investigates the feasibility of improving the design of spherical turbine blades by increasing the ratio of lift to drag. The results show that the Naca airfoil 4412 had the highest lift-to-drag force ratio, which was equal to 19.95. Through the improvement process for the Naca 4412 airfoil, the increase was made by 13.34 %, and the lift-to-drag ratio became 22.61. The study also dealt with the design of a turbine through the improved airfoil. 230 mm. It has the engineering characteristics of the number of helical blades, 5, The measurement of the blade's length chord 15 % of the turbine diameter, and the Angle of Attack, 9.5°
The paper presents the results of influence for manufacturing deviations from the shape of the flow part – cavities obtained during the refinement of the material part of the multistage axial ...compressor GTE-65.1. An approach to the mathematical description of cavities is described, consisting of four steps. This approach allows us to gradually determine the influence of the deviation on the characteristics of the compressor. For each of the four steps the integral characteristics of the compressor deviations in efficiency and the total pressure ratio are compared to the base geometry. The change in the stability of the compressor is analyzed, taking into account the cavities under consideration. The analysis of changes in the parameters of the compressor stages is carried out.
•In order to demonstrate the ability of CFD codes to predict the complex phenomena of mixing flow, the results of numerical simulations of the ROCOM PTS experiments, which the IAEA proposed as an ...international open reference, are presented in this paper. A comparison between the calculated results produced by the commercial code Ansys CFX. 2022.R1 and the measurements from the experimental setup was made.•In both normal operation and accident scenarios, the phenomenon of coolant mixing at various temperatures in the primary circuit of pressurized water reactors (PWR) is significant. In this study, we explore the pressurized thermal shock (PTS) phenomena, which refers to a situation that threatens the integrity of the reactor pressure vessel (RPV).•The sole mechanism capable of preventing a reactivity insertion brought on by a temperature perturbation introduced into one of the loops during an overcooling transient is the slug mixing phenomena. For Pressurized Thermal Shock (PTS) scenarios, mixing water slugs of various temperatures is also crucial.•As typical one-dimensional codes are unable to anticipate these phenomena with the appropriate accuracy and spatiotemporal resolution, three-dimensional CFD codes must be used in this study to predict the transient flows of the coolant mixing event associated to thermal stratification. The nuclear industry now acknowledges that CFD codes have matured to the point where they can be used in nuclear power station design.•In order to solve specific safety concerns in nuclear power plants, CFD is already well-established. Further modeling work on the intricate physical processes involved, as well as the development of effective numerical schemes required to solve the fundamental equations in an efficient manner, including advanced turbulence modeling, are required for the development, verification, and validation of CFD codes in relation to NPP design.
The current paper documents the Computational Fluid Dynamics (CFD) code validation activity, carried out at the Nuclear Research Center of Birine relevant of Atomic Energy Commission of Algeria as part of International Atomic Energy Agency (IAEA) Coordinated Research Project (CRP): Application of Computational Fluid Dynamics Codes for Nuclear Power Plant Design to assess the current capabilities of these codes and to contribute to technological progress in their verification and validation. A set of ROCOM CFD-grade test data of Pressurized Thermal Shock test (PTS) specifications was made available in the framework of this (CRP) by Helmholtz Zentrum Dresden-Rossendorf, (HZDR) Germany, to perform detailed calculations of the proposed test. The reference point is the injection of relatively cold core cooling water (ECC), which can induce buoyant stratification. The data obtained from the PTS experiment were compared with the results of Ansys-CFX calculations in this paper. Unsteady Reynolds-Averaged Navier-Stokes (URANS) model is used to examine the buoyancy-influenced flows in the reactor pressure vessel for condition where natural circulation is a dominant factor. The Shear Stress Transport (SST k-ω) turbulence model is used to take into account the turbulence effects on the mean flow. Calculation results show a good qualitative and quantitative agreement with the experiment data.
To build a new nuclear power plant, it is necessary to take into consideration certain parameters concerning the site selection, among which is the availability of cooling water. The cooling water ...system is made up of two circuits: a closed primary circuit and a secondary condensation circuit that uses water from the sea or the river. This last circuit consumes a lot of water, some of which evaporates into the atmosphere. To save the wasted water, we realized a prototype of a Small-scale Novel Vortex Tower (SNVT) on a laboratory scale, simulating the cooling water of the secondary circuit. The SNVT is a device that generates an artificial vortex as part of the preliminary design of a Vortex Tower for nuclear power plant applications. During operation, the extracted airflow to the top is heated and cooled by contact with ambient air temperatures at the exit of the vertical section of the chimney. A numerical study using the ANSYS-CFX/ CFD package is used to predict the flow and performance parameters of the realized SNVT. To do this, a realistic domain of the flow model, such as geometry and mesh, is developed and executed. In order to solve the governing equation, the turbulent SST model with buoyancy is used. Alternatively, the influence of inflow air velocity, hot source temperature, and mass flow created is investigated. The air enters the SNVT device at a low velocity of 0.1 m/s, passes through the hot source (the water tank), and enters the vortex producing zone via the air guide vanes installed in this convergence chamber. The calculated findings that the SNVT may generate airflow with a maximum velocity of 4.38 m/s. Therefore, we intended to generate electrical energy using a turbine device while also removing energy from the hot source using artificial vortex production. The results are compared to previous literature research and found to be in good agreement.
•A spherical-shaped Darrieus hydrokinetic turbine (SDHKT) was used in the pipeline.•Six different SDHKT models were designed by changing diameters, solidity, and blade number.•Performance analysis ...was done experimentally and numerically with varying pipe flow.•The performance of the turbines improved with the increased blockage ratio.•Pressure drop across the turbines increased with increasing TSR and increasing pipe flow.
The present study aimed to explore the applicability of Darrius hydrokinetic turbine (HKT) curbed inside a closed conduit, i.e., in-pipe hydropower system. Six numbers of 3- and 4-bladed Spherically shaped Darrieus HKTs (SDHKT) were designed having various diameters. Numerical analysis was performed in ANSYS CFX to calculate performance parameters, viz. coefficient of power (CP) and coefficient of torque (Ct), to get an idea of possible power production. Numerical analysis was conducted by varying fluid flow from 0.5 to 2.0 m/s with an increment of 0.5 m/s. Blockage ratios (BR) were maintained as 0.705, 0.796, and 0.893 for an 0.080 m (nominal) diameter pipe. The results were validated with experiments at 1.0 ± 0.2 m/s flow velocity. It was found that CP increased with the blockage ratio. In general, the performance of the 4-bladed SDHKT was found better than the 3-bladed SDHKT. However, the performance of 3- and 4-bladed SDHKTs at a BR of 0.796 were considered for further analysis due to operational constraints. It was observed that overall CP increased with fluid velocity but with less proportionate. Pressure drops across the turbine increased with increased TSR and fluid flow velocities inside the pipe.
This study aims to explore the effect of various design parameters, such as maximum airfoil thickness, maximum camber in the blade profile, maximum camber position, helical pitch, blade pitch angle, ...solidity, and number of blades, on the performance of helical Darrieus hydrokinetic turbines (HDHKTs). An experimental and numerical performance analysis was conducted, corresponding to free-stream velocity of 0.5 m/s. The performance increased with increasing airfoil thickness, up to a maximum of 21%. Effects of the maximum camber and position of the maximum camber on the performance of the turbine were insignificant. The analysis was extended to different helical pitch angles on the NACA 4421 profile. The performance increased with increasing helical pitch angle; however, the operating range of tip speed ratio decreased. The blade pitch angle had an insignificant effect on the turbine performance. Furthermore, the HDHKT of the NACA 4421 blade profile consist of two-, three-, four-, five-, and six-blade turbine performances was examined for different solidity values. For solidity values of 0.10, 0.15, and 0.20, the three-blade HDHKT performed the best. For solidity values greater than 0.20, the four-blade HDHKT performed the best. The four-blade HDHKT had the highest coefficient of power among all the HDHKTs.
•Performance analysis is performed both experimentally and numerically for three-blade and four-blade HDHKTs.•Blade thickness effect of NACA 4421 is better among NACA 4412, NACA 4415, NACA 4418, NACA 4421, NACA 4424 and NACA 4428.•Increase in helical pitch angle within the range of 30° to 60°, the performance of NACA 4421 increases.•Maximum camber, position of maximum camber and blade pitch angle have insignificant effect on HDHKT performance.•For solidity 0.10. 0.15 and 0.20 three-blade HDHKT performed well and beyond this four-blade performed best.
This research article focuses on improving the efficiency of an axial flow compressor stage, enhancing the stall margin, and optimizing flow parameters. Utilizing the NACA 65 series rotor airfoil ...with 12 blades, the study employs numerical simulations using the K-epsilon turbulence model. The model is validated with experimental data under specific boundary conditions, including a total pressure at the intake and a static pressure at the exit, initially set at atmospheric pressure. The outlet static pressure is incrementally increased until the rotor reaches stall. At this stall point, the tip injection method, a well-known active flow control technique, is implemented to mitigate flow instabilities. Injectors are placed at the leading edge of the rotor blades, distributed circumferentially. The tip injection parameters include 0.3% of the total mass flow rate, a pitch angle of 30 degrees and yaw angles ranging from −15 to +15 degrees. The analysis shows a stall margin improvement (SMI) of 14.26% with the 0.3% total mass flow rate injection. A decrease in the yaw angle reduces blockage and promotes smoother flow over the rotor blade, with the optimal stall margin enhancement occurring at an adverse yaw angle of −15 degrees. This study demonstrates significant SMI in the axial flow compressor rotor using specific active flow control parameters, particularly highlighting the critical role of adverse yaw angles in the tip injection method in enhancing stall margin, contributing to overall efficiency and stability.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The Helical Savonius hydrokinetic turbines (HSHKT) are regarded as the beneficiary equipment to increase the power generation in low head rivers. This study investigates the performance of HSHKT ...arranged in arrays. Firstly, performance analyses of two HSHKT rotors are experimentally performed, arranged in inline formation along the fluid flow direction, for different spacing between them (L). These spacing are considered 3D (D = rotor diameter), 3.5D, 4D, 4.5D, 5D, and 5.5D. Experiments are performed in a hydraulic flume of 6 m length at 0.5 m/s velocities for different loading conditions. The optimum performance (i.e., coefficient of power and coefficient of torque) of both HSHKTs together is obtained at a distance of 4D. Consequently, the study is simulated through the ANSYS-CFX for 0.5 m/s upstream velocity and optimum performance is validated at L = 4D. Further, the study is extended in ANSYS-CFX for three HSHKTs arranged in arrays of different patterns, namely triangular and staggered formation. The analysis is performed for different velocities and varying distances between them. It is observed that at a 4D distance, the optimum performance of the three HSHKTs is achieved. Moreover, it is also found that HSHKT performance is better in staggered formation compared to the triangular formation.
•Implementation of Helical Savonius Hydrokinetic turbines in array to increase the power generation.•Performance analysis of Helical Savonius Hydrokinetic turbines is done, arranged in an array at distance of L = 3D–5.5D.•Inline formation consists of two rotors whilst, triangular and staggered formations are considered for three rotors to increase the efficiency within optimal space.•At L = 4D, optimum performance is obtained in the inline formation.•Triangular formation gives better performance than staggered formation at L = 4D optimal distance.
Turbine is a hydraulic engine where energy transfer occurs both based on the kinetic energy and potential (pressure) of the water. In this article we have designed the Spiral Turbine Casing – ...Impeller assembly with dimensions, geometry from technical documentation forms and the articles of other authors. CAD design of this assembly is a challenge and was done using .NX SIEMENS. The study of the fluid flow was done with ANSYS CFX by importing this assembly, some conclusions were drawn regarding the fluid velocities and the pressure field. The cavitation phenomenon that may occur in the operation of the turbine was also taken into account and some conclusions were drawn regarding the effects of this phenomenon. If the presence of vapours in the hydraulic circuit is found, then the cavitation can develop and this fact can be highlighted with Vapour Volume Fraction.
Micro gas - turbines (MGT) offer many advantages such as higher thermal efficiency and reduced noise, and are suitable sources for power generation due to their fuel flexibility, small sizes, and ...high efficiencies. In recent years, there has been an increase interest in developing MGT for transportation platforms such as Range Extender for Electric Vehicle (REEV), Unmanned Ground/Air Vehicles (UGV/UAV), Auxiliary Power Units (APU). For these applications, the MGT must meet essential requirements like reliability, reasonable price, ecological safety, low noise and vibration, multi-fuel, etc. This paper presents the numerical and experimental investigation of a newly designed annular type combustion chamber. This combustion chamber is part of a 40 daN micro gas turbine, destined to equip a small-scale multifunctional airplane. The combustion chamber is equipped with six innovative vaporizers, using Jet-A as fuel, patented by INCDT COMOTI. The experimental installation on which the combustion tests have been performed consists of: the fuel supply system, an air source, the combustion chamber assembly, a chimney for flue gas exhaust. During the combustion chamber testing campaign, the following parameters have been monitored and registered: air mass flow, air temperature, and pressure before the combustion chamber entrance, the temperature at the combustion chamber exit, the temperature before the pressure regulating valve placed on the exhaust pipe. After the testing campaign has been concluded the numerical simulations have been resumed. A three-dimensional RANS numerical integration of the Navier-Stokes equations has been carried out, using an Eddy Dissipation Combustion Model (EDM) and the k-ε turbulence model, implemented in a numerical simulation conducted using the commercial software ANSYS CFX. The computational domain has been modified in order to match the testing rig. Due to the complex geometry of the computational domain, an unstructured type computational grid has been used. The imposed boundary conditions have been changed in order to match the testing conditions and functioning regimes. A kerosene – air two steps reaction mechanism, with NO formation, has been used. The numerical simulation results have been compared with the parameters measured experimentally, thus validating the obtained results.
