Application of an innovative jet pump system for the sediment management in a port channel: Techno-economic assessment based on experimental measurements

open3noThe realization of infrastructures in coastal environment modifies water and sediment natural current regime. In particular, sediment can be entrained and accumulated in port infrastructure like docks, haling basins, or port entrances and channels, creating problems for navigation and limiting the human activities. The result is that marine basins and approaches are frequently silted and require maintenance dredging. Dredging is a consolidated and proven technology which implies relevant drawbacks, like high environmental impact on marine flora and fauna, mobility and diffusion of contaminants, and pollutants already present on the seabed, limitations to navigation, relatively high and low predictable costs. Starting from 2001 an innovative plant for sediment management, alternative to maintenance dredging, has been developed and tested. The core of the plant is the "ejector", an open jet pump fed by pressurized water that is able to suck and convey in a pipeline the sediment that may accumulate in a certain area. On August 2018, a pilot plant has been installed in the haling basin of Cattolica (Italy), as part of a pilot initiative included in the Interreg-Med project "Promoting the co-evolution of human activities and natural systems for the development of sustainable coastal and maritime tourism" (CO-EVOLVE). The aim of the specific experimental activity was to test and monitor the efficacy of the technology applied in a port channel and working with sediments like silt and clay instead of sand. The paper shows the results of the monitoring campaign carried out by the University of Bologna from August 2018 to July 2019.openPellegrini M.; Preda G.; Saccani C.Pellegrini M.; Preda G.; Saccani C

Experimental study on the mixing of confined coaxial jets

The turbulent mixing of coaxial confined jets is a complex dynamic process that is applied in a large number of devices such as the engineering ejectors, pumps jet, industrial burners, combustion chambers of jet engines, nuclear rockets gas, mixing chambers of turbofans, afterburners, and so on. The study of the aerodynamic performance of coaxial jets in different types of confinement also has a fundamental interest because it involves the interaction of different turbulent flow phenomena, whose details are not yet very well known quantitatively. The parameters that are involved in the process of mixing and are primarily responsible for the complexity of the process are both geometric or operational parameters such as: velocity, temperature or density ratios, compressibility effects, levels of turbulence of jets, pressure gradient, interaction between the walls and the jets or the ratio between the diameters of the mixing duct and the internal jet nozzle. In the literature several studies report the influence of some geometrical parameters and operating in the process of turbulent mixing. Turbulent mixing of two parallel streams is affected by confinement, velocity ratio, and turbulent intensity. The objective of this work is to study the effect of the initial levels of turbulence of each coaxial jet in the process of turbulent mixing for diameter ratios less than 2, which is the case of very low bypass turbofan engines. The use of convenient turbulent intensity ratios between the inner and the outer flow should be a most effective tool to control the turbulent mixing between the inner and outer flow (θ). The aim of the present work is to study the effect of θ on the flow development and to identify the associated regimes, and in particular the production of a flow reversal in the central zone near the jets exit. To isolate the characteristic radial effects of a cylindrical geometry a bi-dimensional configurations was adopted. The present results were obtained for a velocity ratio, λ, of 2, and turbulent intensities of 30% the mean mass flow velocity (Umean) that correspond to a ratio between the outer and inner jets of θ=1.5. Prior to the measurements flow visualization was performed to give a qualitative picture of the flow and to guide the choice of the measurement locations.A mistura turbulenta de jactos coaxiais confinados é um complexo processo dinâmico com muitas aplicações práticas, como em ejectores, bombas a jacto, queimadores industriais, câmaras de combustão de motores a jacto, foguetes nucleares gasosos, câmaras de mistura, afterburners1, motores turbofan. Nestas últimas aplicações, o confinamento é também de interesse fundamental, porque envolve certos fenómenos de interacção de escoamentos turbulentos, cujos detalhes não estão ainda quantitativamente completamente entendidos. Os parâmetros que estão envolvidos no processo de mistura e que são os principais responsáveis pela complexidade do processo são ambos parâmetros geométricos ou parâmetros operacionais tais como: razões de velocidade, temperatura ou densidade, níveis de turbulência dos jactos, gradientes de pressão, interacção entre as paredes e os jactos ou a relação entre os diâmetros das condutas e mistura do jacto interno. Na literatura, existe alguns estudos que relatam a influência de alguns parâmetros geométricos e operacionais no processo de mistura turbulenta. A mistura turbulenta de dois jactos paralelos é afectada pelo confinamento, velocidade, e intensidade de turbulência. O objectivo deste trabalho é estudar o efeito dos níveis iniciais de turbulência de cada jacto coaxial no processo de mistura turbulenta com razões de diâmetro inferior a 2, que é o caso de motores turbofan de baixo bypass. A utilização de razões de intensidade de turbulência convenientes entre o jacto interior e o exterior deve ser um instrumento mais eficaz para controlar a mistura turbulenta entre o fluxo interior e o exterior (θ). O objectivo do presente trabalho é estudar o efeito de (θ) no desenvolvimento do jacto e identificar os regimes associados, em especial a produção de uma zona de recirculação na zona central perto da saída dos jactos. Para isolar os efeitos das características radiais cilíndricas, foi adoptado uma configuração de geometria bidimensional. Os resultados foram obtidos para uma razão de velocidades, λ, de 2,com intensidades de turbulência próxima dos 30% da velocidade média do fluxo mássico (Umean) que corresponde a uma razão de intensidades de turbulência de θ=1.5. Antes das medições de velocidades no escoamento, foi realizada a visualização para dar uma imagem qualitativa do escoamento para orientar a escolha dos locais de medição

Development of Climbing Robots with Different Types of Adhesion

There is enormous potential in industrial inspection tasks for climbing robots than can work in hazardous environments, climb on different types of surfaces and enter into very small spaces that have difficult access. For example when cleaning, painting, repairing and diagnostic inspection of walls of general buildings, or performing non destructive testing inspection and maintenance of oil storage tanks, nuclear power plants, petrochemical factories, medical applications etc. The paper describes several types of robot adhesion in different environments, some of which have been incorporated into wall climbing robot designs. The adhesion methods discussed generate forces with permanent magnets, vacuum suction cups, propellers, needles or grippers, glue or adhesive tape, and Van der waal’s effect

Numerical study of aerodynamically flow interaction

Esta dissertação é constituída por dois estudos que focam a interacção entre jactos múltiplos em diferentes configurações de escoamento distribuídos em dois temas, o primeiro tema denominado ‘Numerical Study of Aerodynamically Enhanced Mixing’ e o segundo ‘Numerical Study of Twin Impinging Jets Aligned with Low Velocity Crossflow’. O primeiro tema abordada a mistura turbulenta de jactos coaxiais em duas configurações, escoamento confinado e não confinado, para razões de diâmetro inferior a 2 sendo diversas as áreas de aplicação como ejectores, bombas de jactos, câmaras de combustão para motores a jacto e particularmente, motores turbofan com baixa razão de bypass. Simulou-se computacionalmente camadas de corte bidimensionais em escoamentos de mistura de jactos utilizando o modelo de turbulência k – ε, sendo comparados os dados numéricos resultantes da simulação com dados experimentais revelando boa capacidade de simulação para este tipo de escoamento por parte do modelo adoptado. Contudo de salientar a ausência total de qualquer tipo de recirculação apesar da forte interacção verificada entre jactos, e a região de interacção entre o jacto exterior e o jacto interior apresentou elevados níveis de energia cinética turbulenta, na configuração com superfície superior sólida. Múltiplos jactos incidentes alinhados com escoamento cruzado de baixa velocidade representa o segundo tema abordado nesta dissertação sendo um tema de interesse para as mais diversas áreas, entre as quais, o arrefecimento de equipamentos, dispersão de poluentes e em especial para aeronaves VSTOL, ou seja aeronaves com capacidade de descolagem e aterragem vertical ou em curtas distâncias focando particularmente a aeronave F-35 aquando operando em modo VSTOL próximo do solo. Neste estudo simulou-se computacionalmente jactos múltiplos tridimensionais alinhados com escoamento cruzado embatendo numa superfície sólida para 3 razões de velocidade, comparando-se dados numéricos resultantes da simulação computacional com dados experimentais concluindo-se que o modelo computacional subdimensiona o escoamento apesar de terem sido encontrados ground vortex para as duas razões de velocidade mais elevadas.This thesis presents two studies focusing the interaction of multiple jets in two different flows configuration distributed in two themes namely ‘Numerical Study of Aerodynamically Enhanced Mixing’ and ‘Numerical Study of Twin Impinging Jets Aligned with Low Velocity Crossflow’. The turbulent mixture of coaxial turbulent jets in a confined and an unconfined configuration for diameter ratio less than 2 is applied in several devices such as engineering ejector, jets pumps, industrial burners, combustion chambers of jet engines and in particular, turbofan engines with or without afterburners with low bypass ratio. In sequence of this study we simulate computationally a 2D shear layer in a confined and unconfined configuration for diameter ratio less than 2 using the k - ε turbulent model, being compared afterwards the numerical data from computational simulation with experimental results. From this study no recirculation zone where found despite the high levels of turbulent kinetic energy with high values of shear stress between jets and between second jet and solid surface revealing good capabilities of computational simulation for this kind of flow. Multiple impinging jets aligned with a low velocity crossflow represent a subject of interest in several devices such as cooling of equipment, pollution dispersion and specialty VSTOL aircrafts with the capability of vertical take-off being a test case the F-35 aircraft when operating in VSTOL mode near ground. The present 3D computational simulation of multiple impact jets aligned with a low velocity crossflow for three velocity ratios show numerical data underdeveloped in comparison with experimental data despite the presence of ground vortex for the highest two velocity ratios

Aerodynamic control of the mixing of confined, plane and co-axial jets

Turbulent mixing of confined coaxial jets is a complex dynamic process with many practical applications such as ejectors, jet pumps, industrial burners, jet engine combustion chambers, gaseous nuclear rockets, mixing chambers, afterburners, and turbofan engine mixing chambers. In this latter applications the confinement is also of basic interest because it involves a certain interacting turbulent flow phenomena, the details of which are not yet fully understood quantitatively (Ahmed and Sharma, 2000). There have been studies of different geometric and operating parameters on the turbulent mixing process of confined coaxial jets with different motivations. While a wide range of diameter ratios has been investigated in the past, no work was reported on diameter ratios below 2, which is the case with many low bypass turbofan engines with bypass ratios of 0.3 and less. Only Ahmed and Sharma (2000) reported recently detailed LDV measurements of mean and turbulence components of velocity as well as the total and static pressures over a range of velocity ratios with relevance in the present context. In their work they analyse the influence of velocity ratio on the turbulent mixing process, but there are many other parameters which influence the turbulent mixing process. This research is dedicated to the study of the turbulent mixing of parietal jets without any generated effect of swirl and without the presence of bluff bodies. The major objective was to design mixing control strategies using purely aerodynamic tools. Following a work on axisymmetric geometries, a two-dimensional geometry was adopted to study the influence of geometric and initial parameters to control the flow: confinement, inclination angle and turbulence intensity of the outer flow.Fundação para a Ciência e Tecnologia (FCT)Aeronautics and Astronautics Research Center (AeroG)Associated Laboratory in Energy, Transports and Aeronautics (LAETA

Estudo numérico do processo de mistura de jactos coaxiais confinados

A mistura turbulenta de jactos coaxiais confinados é um complexo processo dinâmico com muitas aplicações práticas, como em ejectores, bombas a jacto, queimadores industriais, câmaras de combustão de motores a jacto, foguetes nucleares gasosos, câmaras de mistura, afterburners1, motores turbofan. Nestas últimas aplicações, o confinamento é também de interesse fundamental, porque envolve certos fenómenos de interacção de escoamentos turbulentos, cujos detalhes não estão ainda quantitativamente completamente entendidos. Tem havido estudos do comportamento aerodinâmico de jactos coaxiais em diferentes tipos de geométricas e com diferentes parâmetros operacionais com diferentes motivações. Enquanto que uma larga escala de relações de diâmetros foi investigada no passado, praticamente não há registo de trabalhos para diâmetros inferiores a 2, que é o caso dos motores turbofan com muito baixo bypass2, com razões de bypass de 0.3 ou inferior. Recentemente, foram publicadas algumas medidas detalhadas, obtidas com LDV (Velocimetria Laser) de velocidades médias e intensidade de turbulência, bem como a pressão estática e total acerca desta gama de razões de velocidade com relevância no presente contexto. Contudo, para além da influência das razões de velocidade no processo de mistura turbulenta, existem muitos outros parâmetros que influenciam o processo de mistura turbulenta. Este trabalho é dedicado ao estudo do efeito dos níveis da turbulência inicial no processo de mistura turbulenta dos jactos coaxiais confinados, que recebeu pouca atenção no passado. Os resultados mostram que o efeito da variação da intensidade de turbulência do jacto interior está associado a um padrão de distribuição da energia cinética turbulenta, k, que é praticamente constante, havendo o aparecimento de uma zona de recirculação numa localização praticamente constante a jusante. No caso do efeito da variação da intensidade de turbulência do jacto exterior, a zona de recirculação muda de posição e recua até ao desaparecimento no limite máximo, ou seja, a variação do jacto exterior tem muita influência, predomina.Turbulent mixing of confined co-axial jets is a complex dynamic process with many practical applications such as ejectors, jet pumps, industrial burners, jet engine combustion chambers, gaseous nuclear rockets, mixing chambers, afterburners, turbofan engine. In this latter applications the confinement is also of basic interest because it involves a certain interacting turbulent flow phenomena, the details of which are not yet fully understood quantitatively (Ahmed3 and Sharma4 , 2000). There have been studies of different geometric and operating parameters on the turbulent mixing process of confined co-axial jets with different motivations. While a wide range of diameter ratios has been investigated in the past, no work was reported on diameter ratios below 2, which is the case with many low bypass turbofan engines with bypass ratios of 0.3 and less. Only Ahmed and Sharma (2000) reported recently detailed LDV measurements of mean and turbulence components of velocity as well as the total and static pressures over a range of velocity ratios with relevance in the present context. In their work they analyse the influence of velocity ratio on the turbulent mixing process, but there are many other parameters which influence the turbulent mixing process. This work will be dedicated to the study the effect of initial turbulence levels of confined co-axial jets on the turbulent mixing process, which has received little attention in the past, and the study of pressure gradient

Design demonstrations for the remaining 19 Category B tank systems at Oak Ridge National Laboratory, Oak Ridge, Tennessee

This document presents design demonstrations conducted of liquid low-level waste (LLLW) storage tank systems located at the Oak Ridge National Laboratory (ORNL). Demonstration of the design of these tank systems has been stipulated by the Federal Facility Agreement (FFA) between the US Environmental Protection Agency (EPA)--Region IV; the Tennessee Department of Environment and Conservation (TDEC); and the DOE. The FFA establishes four categories of tank systems: Category A--New or Replacement Tank Systems with Secondary Containment; Category B--Existing Tank Systems with Secondary Containment; Category C--Existing Tank Systems Without Secondary Containment; and Category D--Existing Tank Systems Without Secondary Containment That are Removed from Service. This document provides a design demonstration of the secondary containment and ancillary equipment of 19 tank systems listed in the FFA as Category B. Three tank systems originally designated as Category B have been redesignated as Category C and one tank system originally designated as Category B has been redesignated as Category D. The design demonstration for each tank is presented in Section 2. The design demonstrations were developed using information obtained from the design drawings (as-built when available), construction specifications, and interviews with facility operators. The assessments assume that each tank system was constructed in accordance with the design drawings and construction specifications for that system unless specified otherwise. Each design demonstration addresses system conformance to the requirements of the FFA