Estudio computacional de la mecánica y optimización de un pilar encerrado en un canal

Dado que existen infinidad de procesos industriales en los que una transferencia de calor y/o mezclado eficientes son un objetivo prioritario, en el presente estudio se realiza un análisis de las fuerzas hidrodinámicas de interacción entre un pilar y el desprendimiento de vórtices que este genera, dado su potencial uso como dispositivo de mezclado en aplicaciones en ingeniería mecánica. Esta investigación pretende mostrar diferentes diseños, estudiando diferentes potencias de bombeo necesarias, así como el efecto de los parámetros en la configuración del dispositivo (relación de dimensiones de los lados del pilar, relación entre las dimensiones del pilar respecto al canal y caudal) con el fin de encontrar las configuraciones más eficientes para su diseño final. Los resultados obtenidos demuestran que hay ciertas configuraciones que implican un gran impacto en el desprendimiento de vórtices, mientras que otras configuraciones generan un flujo estacionario/cuasiestacionario aguas abajo, siendo el comportamiento predecible mediante modelos.Los autores agradecen la financiación recibida a través del proyecto UMA18-FEDERJA-184. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Computational Design in Mechanical Engineering Applications via CFD: Uncertainty Quantification and Optimisation

Engineering practice is nowadays inconceivable without the presence of computational tools. Within this context, Computational Fluid Dynamics (CFD) are an essential tool for fluid-based machine design, such as heat exchangers, turbines, cooling processes or aerodynamic performance of vehicles. Among the simulation capabilities of modern softwares, Reynolds-Averaged Navier Stokes (RANS) simulations are the most popular industrial approach, due to the decent computation elapsed times and accuracy for a vast range of applications. However, some engineering applications that simulate complex flows may exhibit certain discrepancies as a consequence of neglected sources of uncertainty. The effect of uncertainty can be even increased when the effect of different sources of inaccuracy are combined in the simulation. Once a reliable computational model is achieved, further designs can be explored. One advantage of CFD is that prototyping costs can be reduced by performing optimisation via simulation. This allows to obtain a large number of data at lower cost than experimental testing. Thus, such data can be further used to train Machine Learning algorithms that may improve or speed up the optimisation process. In this presentation, the aforesaid concepts will be shown. Different examples of uncertainty propagation in CFD simulations of engineering applications will be illustrated. Finally, a successful case of Machine Learning aided optimisation of a mechanical micro heat exchanger/mixer will be presented. This research is supported by the UMA18-FEDERJA-184 funding.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech Investigación subvencionada por: contrato UMA18-FEDERJA-184 y Plan Andaluz de Investigación, Desarrollo e Innovación (PAIDI - Junta de Andalucía

Two-step numerical simulation of the heat transfer from a flat plate to a swirling jet flow from rotating pipe

Purpose: Impinging jets have been widely studied and the addition of swirl has been found to be beneficial to heat transfer. Since there is no literature on RANS nor experimental data of swirling jet flows generated by a rotating pipe, this paper attempts to fill such gap by providing results on the performance of this type of design. Design/methodology/approach: Since the flow has a different behaviour at different parts of the design, the same turbulent model cannot be used for the full domain. To over-come this complexity, the simulation is split into two coupled stages. This is an alternative to use the costly Reynold Stress Model (RSM) for the rotating pipe simulation and the SST k-ω model for the impingement. Findings: To induce swirl by rotating pipes with swirl intensity ranging from 0 to 0.5 affects the velocity profiles but not noticeably the spreading angle. The heat transfer is increased with respect to a non-swirling flow only at short nozzle-to-plate distances H/D < 6, where H is the distance and D is the diameter of the pipe. For the impinging zone, the highest average heat transfer is achieved at H/D = 5 with swirl intensity S = 0.5. This is the highest swirl studied in this work. Research limitations/implications: High-fidelity simulations or experimental analysis may provide reliable data for higher swirl intensities, which is not covered in this work with RANS. Practical implications: This two-step approach and the data provided is of interest to other related investigations (e.g. using arrays of jets or other surfaces than flat plates). Originality/value: This paper is the first of its kind RANS simulation of the heat transfer from a flat plate to a swirling impinging jet flow issuing from a rotating pipe. An extensive study of these CFD simulations has been carried out with the emphasis of splitting the large domain into two parts to facilitate the use of different turbulent models and periodic boundary conditions for the flow confined in the pipe

Two-Dimensional-Based Hybrid Shape Optimisation of a 5-Element Formula 1 Race Car Front Wing under FIA Regulations

Front wings are a key element in the aerodynamic performance of Formula 1 race cars. Thus, their optimisation makes an important contribution to the performance of cars in races. However, their design is constrained by regulation, which makes it more difficult to find good designs. The present work develops a hybrid shape optimisation approach to obtain an optimal five-element airfoil front wing under the FIA regulations and 17 design parameters. A first baseline design is obtained by parametric optimisation, on which the adjoint method is applied for shape optimisation via Mesh Morphing with Radial Basis Functions. The optimal front wing candidate obtained outperforms the parametric baseline up to a 25% at certain local positions. This shows that the proposed and tested hybrid approach can be a very efficient alternative. Although a direct 3D optimisation approach could be developed, the computational costs would be dramatically increased (possibly unaffordable for such a complex five-element front wing realistic shape with 17 design parameters and regulatory constraints). Thus, the present approach is of strong interest if the computational budget is low and/or a fast new front wing design is desired, which is a frequent scenario in Formula 1 race car design.The authors want to acknowledge the financial support from the Ramón y Cajal 2021 Excellence Research Grant action from the Spanish Ministry of Science and Innovation (FSE/AGENCIA ESTATAL DE INVESTIGACIÓN), the UMA18-FEDERJA-184 grant, and the Andalusian Research, Development and Innovation Plan (PAIDI—Junta de Andalucia) fundings. Partial funding for open access charge: Universidad de Málag

Sensitivity and uncertainty quantifications for jet stability analysis

The paper is twofold. It aims first to validate and compare adjoint-based sensitivity and other sensitivity methods and their possible relation to Uncertainty Quantification analysis. These methods, illustrated on a simple toy-models can be a lower cost tool for mathematical analysis of complex problems of industrial interests. The second objective is to propose an Uncertainty Quantification of the compressible single stream jet stability subjected to frequency variation. The governing equations are the low cost model called Parabolized Stability Equations. This objective is strongly related to the noise sensitivity and control studies since it has been demonstrated that noise is originated from K-H instability in such a flow. Later, the adjoint PSE approach will be used, to make the link between sensitivity and UQ analysis as this quantification for Large Eddy Simulations or Reynolds Average Navier-Stokes simulations can be considerably expensive. Envelope curves of the standard deviation are determined and compared with good agreement for small variations of the input parameters in the first toy model. For the jet stability, it has been found that the growth rate is almost insensitive to small frequency variations and, on the other hand, the phases of the amplitude functions of the disturbance are extremely sensitive to frequency

Estimation of the aerodynamic tortuosity of woven/wire screens

The use of wire/woven screens (WSs) is frequent in applications such as particle or insect-proof screen in home/greenhouse/farm with natural ventilation. Although this passive element has been studied for decades, most previous works have focused on relating the airflow performance only to porosity. However, most recent investigations have demonstrated that other pore-related parameters such as constriction factor and tortuosity are necessary for the characterisation of screens. Tortuosity of WSs is a parameter that has been broadly estimated in the literature, whose calculations to date are not physics-based and yield a constant value without dependence on airflow velocity. The present investigation proposes a novel method to calculate tortuosity of WS. The new approach uses the flow potential flow theory to estimate realistic curvatures of the streamlines around the inclined threads of the WS. The calculated tortuosity has been made also velocity-dependent, because its value changes for Reynolds numbers below 200, generally. The accurate estimation of tortuosity is a very important contribution to the field, because it is a missing link to develop a universal model to estimate pressure drop for any WS performance. This calculation has been added to AeroScreen software, which allows to obtain porosity, constriction and tortuosity from geometry data

Semi-Analytical Calculation of Pore-Related Parameters of Wire/Woven Screens

Wire/woven screens have a wide range of applications, from being used as simple mechanical screening device to nanoscreen wicking with nanofluids. The vast number of applications makes important to study these screens with high accuracy, to reduce errors in characterisation and performance predictions. Previous works to date focused either on the study of these screens as a two-dimensional surface (e.g. in ventilation openings as insect-proof screens) or as three-dimensional structures under important assumptions (symmetric mesh, thickness of two times their diameter, linear evolution of the pore area along the thickness). These incomplete modellings introduce errors in applications such as the estimation of permeability of the porous media (two-dimensional porosity is identical for two meshes with the same projected area of pore but different thickness) or computational simulations of ventilation in buildings/greenhouses, where these parameters are imposed as boundary condition. The present investigation shows a method to calculate three-dimensional pore related structural properties semi-analytically for the first time and for any plain square mesh. We found that when sweeping the mesh with a plane parallel to it there are up to six different zones or stretches which can be integrated by a piece-wise approach (here named Discretisation Method). Results demonstrated high accuracy in the calculation of three-dimensional porosity and constriction factor (a parameter that is calculated by integration over the pore volume). Due to the mathematical complexity in the method, a software (AeroScreen v1.0) is available to obtain pore-related structural parameters from diameters, separations and thickness of the screen

On the influence of uncertainty in computational simulations of a high-speed jet flow from an aircraft exhaust

A classic approach to Computational Fluid Dynamics (CFD) is to perform simulations with a fixed set of variables in order to account for parameters and boundary conditions. However, experiments and real-life performance are subject to variability in their conditions. In recent years, the interest of performing simulations under uncertainty is increasing, but this is not yet a common rule, and simulations with lack of information are still taking place. This procedure could be missing details such as whether sources of uncertainty affect dramatic parts in the simulation of the flow. One of the reasons of avoiding to quantify uncertainties is that they usually require to run an unaffordable number of CFD simulations to develop the study. To face this problem, Non-Intrusive Uncertainty Quantification (UQ) has been applied to 3D Reynolds-Averaged Navier-Stokes simulations of an under-expanded jet from an aircraft exhaust with the Spalart-Allmaras turbulent model, in order to assess the impact of inaccuracies and quality in the simulation. To save a large number of computations, sparse grids are used to compute the integrals and built surrogates for UQ. Results show that some regions of the jet plume can be more sensitive than others to variance in both physical and turbulence model parameters. The Spalart-Allmaras turbulent model is demonstrated to have an accurate performance with respect to other turbulent models in RANS, LES and experimental data, and the contribution of a large variance in its parameter is analysed. This investigation explicitly outlines, exhibits and proves the details of the relationship between diverse sources of input uncertainty, the sensitivity of different quantities of interest to said uncertainties and the spatial distribution arising due to their propagation in the simulation of the high-speed jet flow. This analysis represents first numerical study that provides evidence for this heuristic observation

对工业工程实践进行的360度评估调查的多维度定量研究

عادة ما تكون مبادرة الطلاب واستباقيتهم أثناء تطوير فصول الهندسة محدودة للغاية. ومع ذلك, على عكس الفصول النظرية,  يُظهر الطلاب عادةً اهتمامًا أكبر بالممارسات المختبرية للموضوعات. نظرًا لأن الزيادة في عدد المتسربين من الدورات الهندسية ، فضلاً عن انخفاض الالتحاق, هي حقيقة يتم ملاحظتها أكثر فأكثر, تهدف هذه الدراسة إلى التحليل الكمي لتأثير أداة تقييم 360 درجةفي تقييم الممارسات, في مجموعات طلابية مختلفة لفرع الهندسة الصناعية. وبهذا, فإن الهدف من ذلك هو تحقيق العديد من الأهداف: من ناحية, إشراك الطالب في عملية التقييم, ومن ناحية أخرى, معرفة درجة رضاهم عن المجموعات المختلفة بالتقييم 360 درجة, وكذلك رأي حول الترجيح العادل لكل تقييم. لهذا, يتم تقديم منهجية تستند إلى تطبيق التقييم 360 درجة وتصميم المسح مع 23 سؤالا. كانت هناك ثلاث مراحل من عملية التقييم بزاوية 360 درجة: مشتركة( بين الطلاب)ذاتي( من قبل الطالب نفسه) وتقييم غير متجانسة( من قبل المعلم). في البداية ، تم تصميم استبيان ، والتحقق من صحته من خلال تحليل عامل التأكيد, وتم تحليل الردود على أساس 4 مجموعات مختارة: موضوعان من العامين الأول والأخير, وطريقة التقييم, والجنس( ذكر أو أنثى) والدورة( الدرجة أو الماجستير). تم أيضًا تحليل أفضل ترجيح في الدرجة النهائية لكل مقيِّم, واقتراح القيم المثلى من 50٪ -30٪ -20٪ للتقييم غير المتجانسة, والمشاركة, والتقييم الذاتي, على التوالي. بالإضافة إلى ذلك, أظهرت النتائج درجة عالية من الرضا من جانب المجموعات التي تم تحليلها من خلال الاستبيان وتعكس نضج الطالب.Initiative and proactiveness shown by students during engineering lectures is usually very limited. However, students usually show high levels of interest in practical laboratory sessions. In order to address increasing dropout from engineering courses, as well as decreased enrollment, the present study aims to quantitatively analyze the impact of a 360-degree feedback survey for evaluating practical sessions. Analysis was conducted overall and as a function of industrial engineering students. Several objectives are intended to be achieved. Firstly, the study aimed to engage students in the evaluation process and, secondly, identify satisfaction with 360-degree feedback as a function of different groupings, whilst, at the same time, gathering opinions about the fairness of evaluation. To this end, a methodology based on the application of 360-degree feedback was applied and a 23-question survey was administered. The following three stages were followed for the 360-degree feedback evaluation process: co- (between students), self- (the student themself) and hetero-evaluation (lecturer). Initially, a questionnaire was designed and validated using confirmatory factor analysis. Responses were analyzed as a function of 4 groups: module (one first- and one third-year module), evaluation type, sex (male or female) and degree level (BSc or MSc). The most appropriate weighting to be applied to each evaluation in order to produce a final overall score was also analysed. This suggested optimal values ​​of 50%, 30% and 20% for the hetero-, co- and self-evaluations, respectively. Additionally, outcomes revealed a high degree of satisfaction for all analysed groupings and high level of maturity in participating students.La iniciativa y la proactividad del alumnado de Ingeniería durante el desarrollo de las clases teóricas es normalmente muy limitada, al contrario que en las prácticas de laboratorio donde muestra más interés. Se constata un aumento del abandono en las carreras de ingeniería y una disminución de matriculados y este estudio tiene como finalidad analizar cuantitativamente el impacto de una herramienta de evaluación 360 grados encuestada en la evaluación de prácticas en estudiantes de ingeniería industrial. Se pretenden lograr varios objetivos: por un lado, implicar al estudiante en el proceso de evaluación y, por otro, conocer su grado de satisfacción con este tipo de evaluación, así como su opinión sobre la ponderación justa. Se Sigue una metodología basada en la aplicación de la evaluación 360 grados y un diseño de encuesta con 23 preguntas. Las etapas del proceso de evaluación 360 grados fueron tres: co- (entre estudiantes), auto- (por el propio estudiante) y hetero-evaluación (por el docente). Se diseñó un cuestionario, validado mediante análisis factorial confirmatorio, y se procedió al análisis de las respuestas en base a 4 agrupaciones seleccionadas: dos asignaturas de primeros y últimos cursos, modalidad de evaluación, sexo (hombre o mujer) y ciclo (Grado o Máster). También se ha analizado la mejor ponderación en la calificación final para cada evaluador, proponiéndose como óptimos los valores 50%-30%-20% para la hetero-, co- y autoevaluación, respectivamente. Los resultados muestran un elevado grado de satisfacción por parte de los grupos analizados a través de la encuesta y adecuada maduración del estudiante.A iniciativa e a proatividade dos alunos durante as aulas de engenharia são geralmente muito limitadas. No entanto, ao contrário os alunos tendem a mostrar mais interesse pelas práticas laboratoriais das disciplinas. Dado que o aumento de desistências nos cursos de engenharia, bem como a diminuição de matrículas, este estudo tem como objetivo analisar quantitativamente o impacto de uma ferramenta de avaliação de 360 graus inquirida na avaliação de aulas práticas, em estudantes da engenharia industrial. Pretende-se, assim, atingir vários objetivos: por um lado, envolver o estudante no processo de avaliação e, por outro, conhecer o seu grau de satisfação de diferentes grupos com avaliação, bem como a sua opinião sobre a ponderação justa de cada avaliação. Para isso, apresenta-se uma metodologia baseada na aplicação da avaliação de 360 graus e a elaboração de um questionário com 23 perguntas. As fases do processo de avaliação de 360 graus eram três: co- (entre estudantes), auto- (pelo próprio estudante) e heteroavaliação (pelo docente). Inicialmente, foi elaborado um questionário, validado por análise fatorial confirmatória, e procedeu-se à análise das respostas com base em 4 grupos selecionados: duas disciplinas dos primeiros e últimos anos, modo de avaliação, sexo (masculino ou feminino) e ciclo (Licenciatura ou Mestrado). Foi também analisada a melhor ponderação na nota final para cada avaliador, propondo-se como ótimos os valores 50%-30%-20% para a hetero-, co- e autoavaliação, respetivamente. Além disso, os resultados revelaram um elevado grau de satisfação por parte dos grupos analisados através, o que reflete a maturidade do estudante.A iniciativa e a proatividade dos alunos durante as aulas de engenharia são geralmente muito limitadas. No entanto, ao contrário os alunos tendem a mostrar mais interesse pelas práticas laboratoriais das disciplinas. Dado que o aumento de desistências nos cursos de engenharia, bem como a diminuição de matrículas, este estudo tem como objetivo analisar quantitativamente o impacto de uma ferramenta de avaliação de 360 graus inquirida na avaliação de aulas práticas, em estudantes da engenharia industrial. Pretende-se, assim, atingir vários objetivos: por um lado, envolver o estudante no processo de avaliação e, por outro, conhecer o seu grau de satisfação de diferentes grupos com avaliação, bem como a sua opinião sobre a ponderação justa de cada avaliação. Para isso, apresenta-se uma metodologia baseada na aplicação da avaliação de 360 graus e a elaboração de um questionário com 23 perguntas. As fases do processo de avaliação de 360 graus eram três: co- (entre estudantes), auto- (pelo próprio estudante) e heteroavaliação (pelo docente). Inicialmente, foi elaborado um questionário, validado por análise fatorial confirmatória, e procedeu-se à análise das respostas com base em 4 grupos selecionados: duas disciplinas dos primeiros e últimos anos, modo de avaliação, sexo (masculino ou feminino) e ciclo (Licenciatura ou Mestrado). Foi também analisada a melhor ponderação na nota final para cada avaliador, propondo-se como ótimos os valores 50%-30%-20% para a hetero-, co- e autoavaliação, respetivamente. Além disso, os resultados revelaram um elevado grau de satisfação por parte dos grupos analisados através, o que reflete a maturidade do estudante.在工程课上，学生表现出来的主动性和积极性往往不高。但跟理论课相反，在学科实验课上学生常常表现出更多的兴趣。考虑到工程专业逐年提升的弃学率，和逐年下降的注册率，该研究希望对一测量工具的影响进行定量分析。该工具可以在360度的范围内对工业工程专业的不同学生群体进行实践评估，以此来达成以下目标：一让学生参与到评估过程；二通过360度评估了解不同群体的满意度以及他们对每项评估权重的意见。为了实现上述目标，研究使用360度评估方法和包含23个问题的问卷调查。360度评估过程分为三个阶段：相互评估（学生与学生之间）、自我评估（由学生自己进行）和异体评估（由老师进行）。首先设计了一个通过验证性因素分析的问卷，然后对问卷答案进行分析。我们将答案分成四组：低年级和高年级的两门课程、评估类型、性别（男或女）以及学历周期（本科或研究生）。除此之外我们还对每项评估员最终打分的最优权重进行了分析，提出异体、相互和自我评估阶段的最佳值为50%、30%和20%。最后问卷结果还显示出不同分析群体的满意度都很高，这也一定程度上反映了学生的成熟度