Analysis and design of a new updraft free-exit-flow low-head hydropower turbine system

A new updraft free-exit-flow low-head hydropower turbine system is designed to enhance tailrace water quality, to minimize fish mortality in turbine flow passage, to improve turbine mechanical performance, and to reduce costs and time of hydropower development. This study applies the theoretical, experimental, and computational approaches to analyze the characteristics of this turbine and to develop improved methods for designing the turbine system components.;The theoretical component of this study contains the flow analysis for the new turbine based on the fundamental principles of fluid dynamics. It analyzes important aspects of turbine flow characteristics such as anti-gravitational flow, spiral flow, helical flow, energy conversion, meridional flow, inflow velocity moment distribution, and variation of velocity moment in the turbine runner. The analysis leads to the proposal of a set of principles, criteria, and methods for hydraulic design of the new turbine. They include mainly an approach for designing the divergent runner chamber and a two-dimensional method for hydraulic design of runner blades. These methods are applied to design a new sample prototype turbine.;Pilot turbine experiments and computational flow analyses are also conducted to investigate the performance and to evaluate and optimize the turbine design. The experiments give encouraging results on the turbine efficiency. They also intuitively demonstrate the new turbine\u27s capability of improving downstream water quality. The experimental results are used to confirm creditability of the numerical models. The numerical flow computations provide detailed flow information in flow passage of both the pilot turbine and the sample prototype turbine. Turbine hydraulic efficiency is estimated based on the computational results. The numerical flow analysis approach is also used to extend the turbine performance curves obtained in the experiment, to identify the initial pilot turbine design insufficiency, and to predict the turbine efficiency under optimal inflow conditions. The flow analyses for the sample prototype turbine evaluate the validity of the proposed design methods for the new turbine. They also identify the potential areas of design improvement for the sample turbine. Initial design optimizations are performed. The improved sample prototype turbine can reach a hydraulic efficiency of 82.2%. The flow patterns in the improved sample turbine are presented. Fish paths in the turbine flow passage are illustrated

Interpretation of cavitation using CFD simulation as a low-cost learning activity compatible with e-learning

7 p.In this conference paper, an activity based on computational fluid dynamics that allows STEM students to know the phenomenon of cavitation is proposed. Cavitation is a dangerous phenomenon that occurs in pressurized fluid when they rapidly change of pressure in a liquid and a small vapor-filled cavity is generated in regions where the pressure is low. These cavities (or bubbles) are highly damaging to machines and fluid systems. Due to its dangerousness, it is necessary for the engineer to know the consequences of the cavitation and the factors involved in the phenomenon, in order to design solutions that avoid or minimize the damage caused. The design process of the activity starts with a critical analysis to cover the requirements that allow the activity to be carried out in the simplest way possible, using a model and a simplified computational pipeline that allows maximum adaptation to the real phenomenon without the need for laboratory equipment so that it can be integrated into subjects in the field of fluid-mechanics and maintenance engineeringS

Short simulation activity to improve the competences in the Fluid-mechanical Engineering classroom using Solidworks ® Flow Simulation

7 p.In this paper, a short simulation activity based on Computational Fluid Dynamics (CFD) is raised in the context of the Mechanical Engineering Bachelor degree as an effective support to the theoretical lessons, in order to improve the competences of the Fluid-Mechanical course. The activity provides both visual and numerical information that the student must compare critically with respect the results obtained analytically, using the equations explained in the theoretical classroom. The activity is designed so that it can be integrated quickly (due to the shortage of times in the academic calendars). In this manner its total completion does not exceed four hours of simulation class. This is achieved by optimizing the resources, proposing meshing and simulation strategies that consume little computational time and using the package Solidworks® Flow Simulation, that takes advantage of the geometry parametrically modelled with the software itself to automatically establish the computational domain of the fluid for the based-on CFD analysis, saving excessive preparation times and long computational process.S

Aeronautical engineering: A continuing bibliography with indexes (supplement 277)

This bibliography lists 467 reports, articles, and other documents introduced into the NASA scientific and technical information system in Mar. 1992. Subject coverage includes: the engineering and theoretical aspects of design, construction, evaluation, testing, operation, and performance of aircraft (including aircraft engines); and associated aircraft components, equipment, and systems. It also includes research and development in ground support systems, theoretical and applied aspects of aerodynamics, and general fluid dynamics

CFD study of the Rotor-Stator Interaction in a Francis turbine

En el següent treball de fi de grau, el qual forma part d'un projecte dirigit pel CDIF (Centre de Diagnòstic Industrial i Fluïdodinàmica), es pretén realitzar l'estudi del model geomètric d'un prototip real d'una turbina hidràulica. En el present projecte es pretén modelar numèricament mitjançant la mecànica de fluids computacional, a partir d'ara CFD, la màquina hidràulica en qüestió per tal de discretitzar els fenòmens fluïdodinàmics implicats en el seu funcionament. El cos principal de l'estudi es centrarà essencialment en l'anàlisi dels fenòmens que intervenen en la interacció Rotor-Estator: l'efecte potencial i l'efecte de la estela en menor mesura. Per mitja d'imatges de contorns y vectors es pretendrá observar com es el comportament del flux amb el pas dels alebs del rotor en les zones de major interès. Per altra banda, es definiran diversos monitors dins del domini computacional per tal de capturar la informació dels repetits cicles presents en el sistema. Així com determinar les seves principals freqüències característiques

Aeronautical engineering: A continuing bibliography with indexes (supplement 282)

This bibliography lists 623 reports, articles, and other documents introduced into the NASA scientific and technical information system in Aug. 1992. The coverage includes documents on the engineering and theoretical aspects of design, construction, evaluation, testing, operation, and performance of aircraft (including aircraft engines) and associated components, equipment, and systems. It also includes research and development in aerodynamics, aeronautics, and ground support equipment for aeronautical vehicles

PRESSURE MEASUREMENTS INSIDE MULTIPLE CAVITIES OF A TORQUE CONVERTER AND CFD CORRELATION

A torque converter was instrumented with 29 pressure transducers. The pressure transducers were located in multiple cavities. The instrumented cavities included, four transducers mounted on the impeller shell, on the channel between blades. Six transducers mounted on the pressure and suction sides on the middle streamline of a turbine blade. Another seven transducers mounted on the pressure and suction sides of the core, middle and shell streamlines of a stator blade. Seven transducers mounted on the torque converter clutch cavity. Finally, five on the cavity between the pressure plate and the turbine shell. The torque converter was part of a 6 speed front wheel drive transmission and differential, also instrumented with various pressure transducers, thermocouples and a flow meter. The transmission measurements were not in scope for the present work with the exception of the thermocouples, flow meter and torque converter clutch pressure, which approximated torque converter inlet pressure during early stages of the project. A transmission lab was designed and built as part of the investigation. Acquisition of the torque converter pressure data was accomplished with a custom designed and built telemetry system developed for the present study by IRT Telemetrics located in Hancock Michigan. A computational fluids dynamics model was developed using a commercially available software. The computer model was used to correlate with the torque converter measured torques and pressures. The computer model was optimized accuracy of predicted torques and for accelerated solution time. Solution times were reduced from 9 hours to under 40 minutes per speed ratio while the accuracy of torques error varied by up to 6% between tests and simulation. Accuracy of pressure simulated values varied widely depending on the cavity under study. The torque converter inlet flow worked best with 5% turbulence intensity while other cavities such as the toroidal ones were best modeled with a turbulence intensity set to 50%. The computer model was able to predict pressure trends during the many tests completed as part of the investigation. Flow recirculation was seen on the turbine and stator blade passages on the low speed ratios. The recirculation region affected simulated and measured pressures on both sides of the turbine and stator blades as seen in previous investigations. Further studies should be carried out using the model developed as part of this work as a starting point. Further improvements in accuracy and solution time are highly valued by the industry to help reduce costs associated with computer time and development costs associated with inaccuracies

Mathematical Modelling of Energy Systems and Fluid Machinery

The ongoing digitalization of the energy sector, which will make a large amount of data available, should not be viewed as a passive ICT application for energy technology or a threat to thermodynamics and fluid dynamics, in the light of the competition triggered by data mining and machine learning techniques. These new technologies must be posed on solid bases for the representation of energy systems and fluid machinery. Therefore, mathematical modelling is still relevant and its importance cannot be underestimated. The aim of this Special Issue was to collect contributions about mathematical modelling of energy systems and fluid machinery in order to build and consolidate the base of this knowledge