No (3138)
Number of found documents:
3138
Published from
to
Optical and Pneumatic Measurements on TR-U-11 Cascade
Luxa, Martin; Hála, Jindřich; Šimurda, David
2023 - English
The report contains results and evaluation of conducted optical (interferometry and schlieren technique) and pneumatic measurements on the first variant of the new tip section, intended for turbine rotor blade.
Keywords:
transonic flow; rotor turbine blade; tip section
Available at various institutes of the ASCR
Optical and Pneumatic Measurements on TR-U-11 Cascade
The report contains results and evaluation of conducted optical (interferometry and schlieren technique) and pneumatic measurements on the first variant of the new tip section, intended for turbine ...
Comparison of finite element simulation of tungsten nanoindentation with Berkovich and conical indenter
Fiala, L.; Ballo, I.; Kovář, J.; Fuis, Vladimír
2023 - English
Finite Element Method (FEM) was used to study the difference between using Berkovich and conical indenters in nanoindentation test of tungsten specimen. The study was aimed to determine the\nmodulus of elasticity of a tested specimen and how it changes with different indenter. The FEM analysis also revealed that the modulus of elasticity was sensitive to the dimensions of both specimen and the indenter for which were made several numerical calculations with different dimensions.
Keywords:
nanoindentation; FEM; Berkovich indenter; conical indenter; tungsten
Available at various institutes of the ASCR
Comparison of finite element simulation of tungsten nanoindentation with Berkovich and conical indenter
Finite Element Method (FEM) was used to study the difference between using Berkovich and conical indenters in nanoindentation test of tungsten specimen. The study was aimed to determine the\nmodulus ...
Asynchronous time integration while achieving zero interface energy
Dvořák, Radim; Kolman, Radek; Falta, J.; Neühauserová, M.
2023 - English
This contribution deals with an asynchronous direct time integration of the finite-element model. The proposed method is applied to the phenomenon of wave propagation through an elastic linear continuum. The numerical model is partitioned into individual subdomains using the domain decomposition method by means of localized Lagrange multipliers. For each subdomain, different time discretizations are used. No restrictions for relation between subdomain’s time steps are imposed. The coupling of the subdomains is forced by an acceleration continuity condition. Additionally, we use the a posteriori technique to also provide the displacement and velocity continuity at the interfaces, and hence we obtain exact continuity of all three kinematic fields. The proposed method is experimentally validated using the modified SHPB (split Hopkinson pressure bar) setup.
Keywords:
finite element method; direct time integration; asynchronous integration; domain decomposition; localized lagrange multipliers
Available at various institutes of the ASCR
Asynchronous time integration while achieving zero interface energy
This contribution deals with an asynchronous direct time integration of the finite-element model. The proposed method is applied to the phenomenon of wave propagation through an elastic linear ...
Annular Impinging Jets and an Active Control of Hysteretic Effects
Devani, Yogendrasasidhar; Antošová, Zuzana; Trávníček, Zdeněk
2023 - English
An annular impinging air jet with and without flow control was studied experimentally using measurements of the wall pressure and flow velocity by the Pitot probe. To investigate flow control swirling effects, eight synthetic jets were generated from the nozzle center body. The experiments cover Reynolds numbers 4000–10,000 (evaluated from the outer exit diameter of the annular nozzle). For Re<9000, the bistability and hysteresis were identified and two different flow field patterns (A, B) were found under the same boundary conditions. For higher Re>9000, the hysteresis were not found.
Keywords:
annular jet; impinging jet; hysteresis
Available at various institutes of the ASCR
Annular Impinging Jets and an Active Control of Hysteretic Effects
An annular impinging air jet with and without flow control was studied experimentally using measurements of the wall pressure and flow velocity by the Pitot probe. To investigate flow control swirling ...
A new blade cascade for flutter studies
Šnábl, Pavel; Pešek, Luděk; Procházka, Pavel P.; Skála, V.
2023 - English
In this paper, a new blade cascade, developed in the Institute of Thermomechanics, is presented. The geometry of the cascade was modified so now the stall flutter can occur. It has some major construction improvements over the original cascade which now allow more precise and reliable measurements. The stability of the new blade cascade with five NACA 0010 profiles with rotational degree of freedom is assessed by Travelling Wave Mode approach and Aerodynamic Influence Coefficient approach.
Keywords:
blade cascade; stability; travelling wave mode; aerodynamic influence coefficient
Available at various institutes of the ASCR
A new blade cascade for flutter studies
In this paper, a new blade cascade, developed in the Institute of Thermomechanics, is presented. The geometry of the cascade was modified so now the stall flutter can occur. It has some major ...
Reduced modelling of aeroelastic instability in a turbine blade cascade
Pešek, Luděk; Šnábl, Pavel; Prasad, Chandra Shekhar
2023 - English
The contribution deals with the first results on flutter instability of the linear cascade triggered by impulse excitation. Together with experimental results, numerical results obtained by reduced modelling of the cascade using van der Pol model of self-excitation are presented and discussed.
Keywords:
flutter; blade cascade; self-excitation; Van der Pol
Available at various institutes of the ASCR
Reduced modelling of aeroelastic instability in a turbine blade cascade
The contribution deals with the first results on flutter instability of the linear cascade triggered by impulse excitation. Together with experimental results, numerical results obtained by reduced ...
Implementation of a plasticity model with advanced kinematic hardening rule for additively manufactured materials
Marek, René; Parma, Slavomír; Gabriel, Dušan; Džugan, J.
2023 - English
This technical report summarizes particularly the modeling part of the project DP 04_01_NPO “Emission-free technologies for local energy sources replacement” including development of models to describe multi-material 3D printed structures. The work is done in cooperation between COMTES FHT, a.s., the Institute of Thermomechanics of the Czech Academy of Sciences, v.v.i. and PROINNO, a.s. The goal of the project is the development of material models describing the behavior of multi-material components deposited by the direct deposition method (DED) under multiaxial cyclic loading.\nIn the report, a plasticity model suitable for materials prepared by the additive manufacturing method is compiled and used. The model uses Hill's plasticity condition, an advanced multi-component kinematic hardening rule, and an isotropic hardening rule. The associated flow rule is chosen and the implementation assumes the theory of small deformations. All constitutive relationships are presented and discussed for the selected model, and the model is thus fully and unambiguously formulated. The model is analytically integrated for a special case of loading and a special choice of parameters of the plasticity condition, namely transverse isotropy. A discretization scheme for numerical integration and procedures for FE implementation of the model are presented. For the FE implementation, a formulation in the displacement field is assumed, specifically the FE solver Abaqus and the implementation of the model using the UMAT interface are targeted. Several examples of the model's response to monotonic, uniaxial and biaxial cyclic loading trajectories are presented. \n Tato zpráva shrnuje postup prací na dílčím projektu DP 04_01_NPO “Emission-free technologies for local energy sources replacement” zahrnující vývoj modelů pro popis chování multi-materiálových 3D tištěných struktur řešený v konsorciu COMTES FHT, a.s., Ústav termomechaniky AV ČR, v.v.i. a PROINNO, a.s. Cílem projektu je vývoj materiálových modelů popisujících chování multi-materiálových komponent deponovaných metodou přímé depozice (DED) pří víceosém cyklickém zatěžování. \nVe zprávě je sestaven a použit model plasticity vhodný pro materiály připravené metodou aditivní výroby. Model využívá Hillovu podmínku plasticity, pokročilý vícesložkový model kinematického zpevnění a model isotropního zpevnění. Je zvolen asociovaný zákon tečení a implementace předpokládá teorii malých deformací. Pro zvolený model jsou uvedeny a diskutovány všechny konstitutivní vztahy a model je tak plně a jednoznačně formulován. Model je analyticky integrován pro speciální případ zatěžování a speciální volbu parametrů podmínky plasticity, konkrétně příčnou isotropii. Je prezentováno diskretizační schema pro numerickou integraci a procedury pro MKP implementaci modelu. U MKP implementace se předpokládá formulace v poli posunutí, konkrétně je pak cíleno na MKP řešič Abaqus a implementaci modelu pomocí rozhraní UMAT. Je prezentováno několik příkladů odezvy modelu na monotónní, jednoosé a víceosé cycklické zatěžovací trajektorie.\n
Keywords:
plasticity; anisotropy; additive manufacturing
Available at various institutes of the ASCR
Implementation of a plasticity model with advanced kinematic hardening rule for additively manufactured materials
This technical report summarizes particularly the modeling part of the project DP 04_01_NPO “Emission-free technologies for local energy sources replacement” including development of models to ...
Posouzení výpočtové dokumentace zaměřené na hodnocení analýzy dopradu zvýšení výkonu bloků EDU II na vibrace potrubí NV a posouzení vlivu zvýšení průtoku média na vibrace parovodů a uložení potrubí
Šulc, Petr; Pešek, Luděk; Gabriel, Dušan
2023 - Czech
Tato technická zpráva byla vypracována pro Státní úřad pro jadernou bezpečnost v rámci zakázky 772201-Expertní podpora SÚJB v oblasti hodnocení pevnosti a životnosti strojních komponent. Zpráva byla vypracována jako posudek k technické zprávě ÚJV DITI 2301/1350: 6729 - Využití projektových rezerv EDU II - 6.3 - analýzy vibrací POTRUBÍ nV a 6.03 Posouzení vlivu zvýšení průtoku média na vibrace parovodů a uložení potrubí vypracované pracovníky oddělení Hodnocení pevnosti a životnosti ÚJV Řež, a. s. a pracovníky Ústavu aplikované mechaniky Brno, s.r.o.. Účelem zprávy [T574/23] bylo podat SÚJB vlastní odborné stanovisko / nezávislé vyjádření k výrokům autorů zprávy ÚJV Řež. V souladu s požadavkem SÚJB byl při zpracování posudku kladen důraz zejména na dynamické aspekty dané problematiky. Posuzovatel zaujal k předložené zprávě ÚJV souhlasné stanovisko s několika drobnými připomínkami vesměs formální povahy. This technical report has been prepared for the State Office for Nuclear Safety within the framework of the contract 772201-Expert support to SÚJB in the field of strength and durability assessment of machine components. The report was prepared as an opinion to the technical report UJV DITI 2301/1350: 6729 - Utilisation of EDU II design reserves - 6.3 - Vibration analysis of the PIPELINE nV and 6.03 Assessment of the effect of increased media flow rate on the vibration of steam pipelines and pipeline embedment prepared by the staff of the Strength and Durability Assessment Department of UJV Rez, a. The purpose of the report [T574/23] was to provide the SAJB with its own expert opinion / independent opinion on the statements of the authors of the ÚJV Řež report. In accordance with the requirement of the SNCB, the emphasis in the preparation of the report was placed on the dynamic aspects of the issue. The assessor took a favourable opinion on the submitted UJV report with a few minor comments, mostly of a formal nature.\n\n
Keywords:
vibration; steam pipe; feed water pipe; steam generator
Available at various institutes of the ASCR
Posouzení výpočtové dokumentace zaměřené na hodnocení analýzy dopradu zvýšení výkonu bloků EDU II na vibrace potrubí NV a posouzení vlivu zvýšení průtoku média na vibrace parovodů a uložení potrubí
Tato technická zpráva byla vypracována pro Státní úřad pro jadernou bezpečnost v rámci zakázky 772201-Expertní podpora SÚJB v oblasti hodnocení pevnosti a životnosti strojních komponent. Zpráva byla ...
Studie rozptylu nebezpečného polutantu v podzemní místnosti
Nosek, Štěpán
2023 - Czech
Tato studie zkoumala proudění vzduchu a šíření polutantů v podzemní místnosti s využitím dvou různých metod ventilace: přirozeného a nuceného větrání. Experiment byl prováděn na zmenšeném modelu místnosti v aerodynamickém tunelu pomocí fyzikálního modelování. Základními cíli bylo porozumět chování proudění vzduchu a rozptylu pasivních polutantů v reálném prostředí za izotermních podmínek. This study investigated airflow and pollutant dispersion in an underground room using two different ventilation methods: natural and forced ventilation. The experiment was conducted on a scale model of the room in a wind tunnel using physical modelling. The main objectives were to understand the airflow behaviour and dispersion of passive pollutants in a real environment under isothermal conditions.
Keywords:
air pollution; atmospheric boundary layer; indoor; natural ventilation; wind tunnel
Available at various institutes of the ASCR
Studie rozptylu nebezpečného polutantu v podzemní místnosti
Tato studie zkoumala proudění vzduchu a šíření polutantů v podzemní místnosti s využitím dvou různých metod ventilace: přirozeného a nuceného větrání. Experiment byl prováděn na zmenšeném modelu ...
The design of Bayesian diagnostic expert system Querix and it’s engineering application
Věchet, Stanislav; Krejsa, Jiří; Chen, K.-S.
2023 - English
Expert systems have gained attention over the last two decades as they bring the possibility of using expert knowledge in various control systems. However, it has lost attraction in favor of artificial neural networks in recent years, which is mostly influenced by the availability of data to train neural network models and the availability of various frameworks to achieve fast time-to-market applications for given solutions.
Keywords:
expert system; decision making; advanced diagnostic; autonomous navigation; RPA
Available at various institutes of the ASCR
The design of Bayesian diagnostic expert system Querix and it’s engineering application
Expert systems have gained attention over the last two decades as they bring the possibility of using expert knowledge in various control systems. However, it has lost attraction in favor of ...
NRGL provides central access to information on grey literature produced in the Czech Republic in the fields of science, research and education. You can find more information about grey literature and NRGL at service web
Send your suggestions and comments to nusl@techlib.cz
Provider
Other bases