Wyniki wyszukiwania - BazTech

1

Numerical and experimental study on seakeeping performance of a high-speed trimaran with T-foil in head waves

Li Ang, Li Yunbo

Polish Maritime Research

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2019

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nr 3

65--77

EN

The longitudinal motion characteristics of a slender trimaran equipped with and without a T-foil near the bow are investigated by experimental and numerical methods. Computational fluid dynamics ( CFD) method is used in this study. The seakeeping characteristics such as heave, pitch and vertical acceleration in head regular waves are analyzed in various wave conditions. Numerical simulations have been validated by comparisons with experimental tests. The influence of large wave amplitudes and size of T-foil on the longitudinal motion of trimaran are analyzed. The present systematic study demonstrates that the numerical results are in a reasonable agreement with the experimental data. The research implied that the longitudinal motion response values are greatly reduced with the use of T-foil.

2

Helicopter flight simulation based on URANS solver and virtual blade model

Stalewski Wieńczysław, Surmacz Katarzyna

Journal of KONES

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2019

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Vol. 26, No. 3

211--217

EN

The methodology of simulation of a rotorcraft flight has been developed and applied to simulate several stages of flight of light helicopter. The methodology is based on coupling of several computational models of Computational Fluid Dynamics, Flight Dynamic. The essence of the methodology consists in calculation of aerodynamic forces acting on the flying rotorcraft by solving during the simulation the Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations. In this approach, the rotorcraft is flying inside the computational 3D mesh modelling the space filled with the air. The flight simulation procedure is completely embedded in the URANS solver ANSYS FLUENT. Flow effects caused by rotating blades of main or tail rotor are modelled by application of the developed Virtual Blade Model (VBM). In this approach, real rotors are replaced by volume discs influencing the flow field similarly as rotating blades. Time-averaged aerodynamic effects of rotating blades are modelled using momentum source terms placed inside the volume-disc zones. The momentum sources are evaluated based on the Blade Element Theory,which associateslocal flow parameters in the blade sections with databases of 2D-aerodynamic characteristics of these sections. Apart of the VBM module, two additional UDF modules support the simulation of helicopter flight: the module responsible for modelling of all kinematic aspects of the flight and the module gathering the momentary aerodynamic loads and solves 6 DOFEquations describing a motion of the helicopter seen as solid body. Exemplary simulation of helicopter flight, starting from a hover, through an acceleration and fast flight until a deceleration and steep descent, has been discussed.

3

Computational simulation of fully trimmed flight of a helicopter in hover

Stalewski Wieńczysław, Zalewski Wiesław, Surmacz Katarzyna, Pulfer Maximilian, Hirsch Frieder

Journal of KONES

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2019

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Vol. 26, No. 1

175--181

EN

In trimmed flight of a helicopter, all the forces and moments, aerodynamic, inertial, and gravitational, are in balance. Keeping the helicopter in trimmed state, needs a precise adjustment of flight controls. The methodology of simulation of a fully trimmed flight of rotorcraft has been developed and applied to simulate hover of a helicopter. The presented approach is based on a solution of Unsteady Reynolds-Averaged Navier-Stokes (URANS) equations. In contrast to typical solutions of such problem, in the newly developed methodology, the flight controls corresponding to the trimmed-flight conditions are also determined based on the solution of URANS equations. The methodology is based on coupling of several computational models of Computational Fluid Dynamics and Flight Dynamic. The URANS equations are solved in a three-dimensional region surrounding the flying helicopter, using the ANSYS FLUENT code. The approach is truly three-dimensional, with truly modelled geometry and kinematics of main and tail rotor blades. This applies to modelling of blade flapping and lead-lag motion, too. The trimming procedure uses six independent parameters (i.e. collective and cyclic pitch of main rotor blades, collective pitch of tail rotor blades, pitch, and bank angles of a helicopter) that should be adjusted so as to balance all forces and moments acting on the helicopter. The detailed description of the developed methodology as well as the results of simulation of trimmed hover of the helicopter was presented.

4

Computational investigations of active flow control on helicopter - rotor blades

Stalewski W., Sznajder K.

Journal of KONES

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2014

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Vol. 21, No. 2

281--288

EN

The paper presents results of the first stage of the research conducted within the frames of Active Rotor Technologies, which is the dynamically developed sub-domain of Rotorcraft Engineering. The research concerned a computational modelling and investigations of new solutions aiming at improvement of performance of modern helicopters and their environmental impact, by active control of operation of their rotors. The paper focuses on one of such solutions applied for the active control of airflow around helicopter-rotor blades. This solution is the Active Gurney Flap – a small, flat tab located at a pressure side of rotor blade near its trailing edge, which is cyclically deployed and stowed during rotation cycles of the blade. The Active Gurney Flap seems to be very promising solution which will enable helicopters to operate with reduced power consumption or reduced main rotor tip speed whilst preserving current flight performance capabilities, especially in terms of retreating blade stall. The newly developed methodology of computational modelling of active-flow-control devices, like Active Gurney Flap, applied for enhance a helicopter performance and improve its environmental impact, has been presented. Development of the methodology was the challenging task, taking into account strongly unsteady character of modelled phenomena and large differences of scales in both the space and time domain, where very small, dynamically deflected tab strongly influences the flow around rotating, large main rotor. Exemplary CFD simulations, presented in the paper, have been conducted to validate developed methodology.

5

Modelowanie metodami URANS i LES przepływu dwufazowego w mieszalniku statycznym z wkładkami typu Kenics

Murasiewicz H., Jaworski Z.

Inżynieria i Aparatura Chemiczna

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2010

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Nr 3

79-80

PL

Zaprezentowano badania numeryczne przepływu burzliwego dwufazowego w mieszalniku statycznym Kenics. W badaniach CFD wykorzystano dwa podejścia: symulacji wielkowirowych LES z modelem dynamicznym kinetycznej energii burzliwości skali podsiatkowej (Dynamie Kinetic Energy Subgrid-Scale Model) oraz metodę symulacji URANS z modelem k-s. Symulacje numeryczne przeprowadzono dla dwóch niemiesza-jących się wzajemnie cieczy: wody i oleju silikonowego oraz dla liczby Re = 10 000. Stwierdzono, że wartości emax będą występować na początku i na końcu wkładki Kenics, co oznacza, iż w tej części wkładki będzie występować proces rozbicia kropel.

EN

Results of numerical modelling of two-phase turbulent flow in a Kenics static mixer were presented. The CFD simulations were carried out using two approaches: 1) large eddy simulation with the dynamic kinetic energy subgrid-scale model, and 2) unsteady RANS method with the k-e model. Numerical simulations were carried out for two immiscible liquids: water and silicone oil, and for the Reynolds number of 10 000. It was observed that higher values of s appeared at the beginning and at the end of the mixer inserts for both modelling approaches. Thus, these regions can be interpreted as the regions of the highest breakup intensity.

6

Modelowanie numeryczne RANS i URANS przepływu burzliwego typu ciecz-ciecz w mieszalniku Kenics

Jaworski Z., Murasiewicz H.

Czasopismo Techniczne. Mechanika

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2008

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R. 105, z. 5-M

187-201

PL

Przedstawiono wyniki modelowania przepływu burzliwego dwufazowego typu ciecz-ciecz w mieszalniku statycznym z dziesięcioma wkładkami Kenics. W badaniach numerycznych wykorzystano technikę RANS i URANS dla liczby Reynoldsa, Re równej 10 000. W modelowaniu CFD przepływu dwóch płynów newtonowskich zastosowano podejście pseudohomogeniczne. Porównano wyniki symulacji uzyskanych dla metody RANS i URANS i sformułowano wnioski.

EN

Results of turbulent, two-phase flow simulations in a static Kenics mixer formed by ten inserts are presented. The computational fluid dynamics study was carried out using both the RANS and URANS approaches. Reynolds number was 10 000. The simulation results obtained for the RANS and URANS methods were compared and conclusions drawn.