An integrated approach to simulate gas turbine secondary air system

© 2023 The American Society of Mechanical Engineers. All rights reserved.One of the most critical parts of a modern gas turbine that its reliability and performance has a great influence on cycle efficiency is the secondary air system (SAS). Modern systems functions to supply not only cooling air flow for turbine blades and vanes but sealing flow for bearing chambers and turbine segments as well as turbine disk s' purge flow in order to eliminate hot gas ingestion. Due to the various interactions between SAS and main gas, consideration of the former is substantially crucial in design and analysis of the whole engine. Geometrical complexities and centrifugal effects of rotating blades and disks, however, make the flow field and heat transfer of the problem so complicated AND too computationally costly to be simulated utilizing full 3-D CFD methods. Therefore, developing 1-D and 0-D tools applying network methods are of great interests. The present article describes a modular SAS analysis tool that is consisted of a network of elements and nodes. Each flow branch of a whole engine SAS network is substituted with an element and then, various branches (elements) intersect with each other just at their end nodes. These elements which might include some typical components such as labyrinth seals, orifices, stationary/rotating pipes, pre-swirls, and rim-seals, are generally articulated with characteristic curves that are extracted from high fidelity CFD modeling using commercial software such as Flowmaster or ANSYS-CFX. Having these curves, an algorithm is developed to calculate flow parameters at nodes with the aid of iterative methods. The procedure is based on three main innovative ideas. The first one is related to the network construction by defining a connectivity matrix which could be applied to any arbitrary network such as hydraulic or lubrication networks. In the second one, off-design SAS calculation will be proposed by introducing some SAS elements that their characteristic non-dimensional curves are influenced by their inlet total pressure. The last novelty is the integration of the blades coolant calculation process that incorporates external heat transfer calculation, structural conduction and coolant side modeling with SAS network simulation. Finally, SAS simulation of an industrial gas turbine is presented to illustrate capabilities of the presented tool in design point and off-design conditions

Evaluating the anti-leech effects of tobacco methanolic extract compared with succinyle choline and some other anti-parasite drugs

زمینه و هدف: زالوها جزء راسته آنالیدا هستند که50 نوع از آن از خون پستانداران تغذیه می کنند. آلودگی به زالو باعث عوارضی شامل: کم خونی شدید، خونریزی، افزایش حساسیت و واکنش آنافیلاکتیک می شود. این مطالعه با هدف بررسی اثر تعدادی از داروهای شیمیایی و گیاهی بر زالو گونه لیمناتیس نیلوتیکا انجام شد. روش بررسی: در این مطالعه تجربی ابتدا تعداد 100 عدد زالو از جنس لیمناتیس نیلوتیکا تهیه و اثر عصاره متانولی تنباکو و داروهای مبندازول، سوکسینیل کولین، مترونیدازول، تریکلابندازول، لوامیزول، نیکلوزاماید و یک تیمار با آب مقطر بر زالو مطالعه شد. حرکات و اثرات داروها به مدت 720 دقیقه مورد مشاهده و بررسی قرار گرفت و زمان فلجی و مرگ زالو ثبت می گشت. یافته ها: با بررسی فلجی و مرگ زالو مشخص شد عصاره متانولی تنباکو با دوز 600 میلی گرم با میانگین 17 دقیقه باعث مرگ زالوها می شود. داروهای تریکلابندازول با میانگین 66/118 دقیقه، لوامیزول با 7 دقیقه، نیکلوزاماید با 66/18 دقیقه و مترونیدازول با 11/541 دقیقه باعث مرگ زالوها شدند. نتیجه گیری: میانگین زمانی نسبتاً کوتاه فلجی و مرگ زالو توسط عصاره متانولی تنباکو و داروهای لوامیزول، نیکلوزاماید، تریکلابندازول نشان از اثرات ضد زالویی این داروها می باشد و ممکن است بتوان از آنها در موارد آلودگی انسانی با زالو گونه لیمناتیس نیلوتیکا استفاده نمود

Analytical Modelling of Electromagnetic Bulging of Thin Metallic Tubes

© 2021 The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. This is the accepted manuscript version of a conference paper which has been published in final form at https://doi.org/10.1007/978-981-15-9505-9_70The main objective of this paper is to develop an analytical method based on the energy balance equation to model the plastic deformation of thin metallic tubes in a high velocity forming process under axisymmetric conditions. A yield criterion is proposed, which involves the coupled effect of the axial and circumferential internal force resultants. Using a combination of power-law strain hardening and strain rate hardening flow stress models, both strain hardening and strain rate effects are included. The proposed method permits consideration of the influence of different terms of kinetic energy and plastic work of the tube. The study presents a typical electromagnetic tube expansion model, using a dynamic high strain-rate forming method with strain-rates above 103 s−1. In this process, the deformation of the workpiece is achieved by the interaction of a current generated in the workpiece with a magnetic field generated by a coil adjacent to the workpiece. The results reveal that the achieved high strain rates influence the plastic flow stress and the final permanent radial deformation, consequently. The study concluded that an appropriate shape function eventuates a more accurate estimation of both the radial displacement and the deformed meridian profile

Solution of minimum spanning forest problems with reliability constraints

We propose the reliability constrained k-rooted minimum spanning forest, a relevant optimization problem whose aim is to find a k-rooted minimum cost forest that connects given customers to a number of supply vertices, in such a way that a minimum required reliability on each path between a customer and a supply vertex is satisfied and the cost is a minimum. The reliability of an edge is the probability that no failure occurs on that edge, whereas the reliability of a path is the product of the reliabilities of the edges in such path. The problem has relevant applications in the design of networks, in fields such as telecommunications, electricity and transports. For its solution, we propose a mixed integer linear programming model, and an adaptive large neighborhood search metaheuristic which invokes several shaking and local search operators. Extensive computational tests prove that the metaheuristic can provide good quality solutions in very short computing times

An overview on the most important native medicinal plants against flour beetle

Contamination with pests is the main problems of stored food products and can defects them from harvest time until storage. Pests have high proliferation rate, global distribution, and sometimes damage foods up to a hundred percent. Nowadays plant materials are used for pest control in warehouses. Volatile essential oils are important compounds to combat fungal pathogens, insects, herbivores and pests in stored food products. Herbs and botanicals have insecticide and insect repellent properties and are good alternative to chemical insecticides. This paper was aimed to have an overview on the most important native medicinal plants against flour beetle. All required information was obtained by searching key words such as flour beetle, medicinal plant extracts or essential oils and Iran of published articles in authentic scientific databases such as Sciencedirect, Blackwell Wiley, Springer, Scopus, Pubmed, Google scholar and Scientific information database (SID) and Magiran. Eucalyptus globulus, Perovskia atriplicifolia, Azadirachta indica Adr. Juss, Artemisia sieberi Besser, Carum copticum C. B. Clarke, Cuminum cyminum L, Bunium persicum Boiss, Elletaria cardamomum Maton, Nerium oleander L, Lavandula officinalis L, Ferula assafoetida L, Rosmarinus officinalis L. Artemisia dracunculus L, Foeniculum vulgare, Satureja hortensis L, Zygophyllum fabago L, Delphinium persicum, Calotropis procera (Ait.) R. Br are the main medicinal plants can affect on flour beetle. They have various compounds and based on the results of phytochemical studies each of active compounds of medicinal plants could have potential anti pest effects against flour beetle. Therefore, it is recommended that all active ingredients are investigated in experimental and pharmacological studies and in case of positive effects, they used for production of natural anti pest compounds against the flour beetle

Explanation and Evaluation of a Four Step Model for Crisis Management Planning Process

The aim of this paper is to assess the crisis management planning process based on a four step's model at South West Power Generation Management Company in IRAN. In this research, the plan of company was assessed to meet contingent crisis based on crisis management planning process containing: finding risks and vulnerable issues, preparing plans and scenarios to meet crises organizing and training management team, and performing plans experimentally. The method of research was descriptive-analytical and statistical population included all 48 personnel of the company in different job levels (Top, Middle, and Executive) who were conferred in a referendum. Research tool as a questionnaire of 27 questions with Cronbach’s Alpha coefficient 0.95 prepared to plan crisis management. This research was conducted by performing a chi-square test to assess questions and “One-variable (t)” test to evaluate hypothesis of research, regard to the complexities of social and human relationships, technologies used in the industry, national and international regulations, climate and region conditions and other effective factors, occurring crisis is seemed as usual and inseparable in the life period of that organization. Thus, the production affairs, human resources and the credit of the organization has been affected and even misguided in their principle goals due to these crises. Therefore, it was revealed the analysis of the findings of this research was weak in comparison with that of theoretical findings.Key words: Crisis management team; Plans and executive scenarios; Quick responds; Crisis management planningRésumé Le but de ce texte est d'évaluer le processus de planification de gestion de crise repose sur un modèle en quatre étapes au sud Power Company West Management génération en IRAN. Dans cette recherche, le plan d'entreprise a été évaluée pour répondre à la crise contingente repose sur la gestion de crise du processus de planification contenant: trouver risques et des enjeux vulnérables, préparation des plans et des scénarios pour répondre aux crises organisation et la formation d'équipe de gestion, et l'exécution des plans expérimentalement. La méthode de recherche a été descriptive-analytique et de la population statistique comprenait tous les 48 du personnel de l'entreprise dans les niveaux d'emploi différentes (haut, milieu et exécutif) qui ont été conférés à un référendum. Outil de recherche comme un questionnaire de 27 questions avec 0,95 Cronbach Alpha coefficient de prêts à un plan de gestion de crise. Cette recherche a été menée en effectuant un test du chi-carré pour évaluer les questions et "à une variable (t)" essai pour évaluer l'hypothèse de recherche, qui concerne la complexité des relations sociales et humaines, les technologies utilisées dans l'industrie, réglementations nationales et internationales , le climat et les conditions de la région et d'autres facteurs efficaces, la crise se produise est paru comme d'habitude et inséparables dans la période de la vie de cette organisation. Ainsi, les affaires de production, ressources humaines et le crédit de l'organisation a été touchée et même erronée dans leurs objectifs de principe à cause de ces crises. Par conséquent, il a été révélé l'analyse des résultats de cette recherche a été faible en comparaison avec celle des résultats théoriques. Mots clés: Equipe de gestion de crise; Les plans et scénarios exécutif; Response rapide; Planification de la gestion des crise

The Effect of Intrathecal Administration of Muscimol on Modulation of Neuropathic Pain Symptoms Resulting from Spinal Cord Injury; an Experimental Study

Introduction: Neuropathic pain can be very difficult to treat and it is one of the important medical challenging about pain treatments. Muscimol as a new agonist of gamma-Aminobutyric acid receptor type A (GABAA) have been introduced for pain management. Thus, the present study was performed to evaluate the pain alleviating effect of intrathecal injection of different doses of muscimol as GABAA receptor agonist in spinal cord injury (SCI) model of neuropathic pain. Methods: In the present experimental study male Wistar rats were treated by muscimol 0.01, 0.1 or 1 µg/10ul, intrathecally (i.t.) three weeks after induction of spinal cord injury using compression injury model. Neuropathic pain symptoms were assessed at before treatment, 15 minutes, one hour and three hours after muscimol administration. The time of peak effect and optimum dosage was assessed by repeated measures analysis of variance and analysis of covariance, respectively. Results: Muscimol with the dose of 0.01 µg in 15 minutes caused to improve the thermal hyperalgesia (df: 24, 5; F= 6.6; p<0.001), mechanical hyperalgesia (df: 24, 5; F= 7.8; p<0.001), cold allodynia (df: 24, 5; F= 6.96; p<0.001), and mechanical allodynia (df: 24, 5; F= 15.7; p<0.001). The effect of doses of 0.1 µg and 1 µg were also significant. In addition, the efficacy of different doses of muscimol didn't have difference on thermal hyperalgesia (df: 24, 5; F= 1.52; p= 0.24), mechanical hyperalgesia (df: 24, 5; F= 0.3; p= -0.75), cold allodynia (df: 24, 5; F= 0.8; p= -0.56), and mechanical allodynia (df: 24, 5; F= 1.75; p= 0.86). Conclusion: The finding of the present study revealed that using muscimol with doses of 0.01µg, 0.1µg, and 1 µg reduces the symptoms of neuropathic pain. Also the effect of GABAA agonist is short term and its effectiveness gradually decreases by time

Design and manufacturing challenges of a microturbine wheel

Micro gas turbine (MGT) is a core technology in many hybrid and integrated power systems to address the low-emission future aviation and decentralisation of energy generation. To achieve a high power-to-weight ratio as well as lowering the required maintenance, a new compact configuration with an air-bearing compartment was developed to build a 2 kW micro gas turbine. Designing a turbine wheel faced a multidisciplinary problem with many inputs and constraints in aerodynamic, heat transfer, strength, and manifesting aspects. To meet all requirements of these aspects, a design procedure is proposed in this paper. Since the manufacturing process affects the performance and life of the system, several processes, including casting, additive manufacturing (AM) and machining of the turbine wheel with different materials, were carried out, and the structural strength and performance of the components were investigated in this study. The prototype was tested experimentally to prove its performance and validate the concept. The cast wheel demonstrated both the required performance of 2 kW power output of the MGT in turbine inlet temperature of 1200 K and rotational speed of 170 krpm. However, the machined and additive manufactured samples for low-temperature/low-speed off-design conditions did not withstand structurally and called for a re-design or change in conditions.European Union funding: Marie Skłodowska-Curie 80160