Applied sciences

Archive of Mechanical Engineering

Content

Archive of Mechanical Engineering | 2009 | vol. 56 | No 2 |

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Abstract

The paper presents numerical simulations related to the problem of how to obtain correct results in transonic wind tunnel during tests at high airfoil angles of attack. At this flow conditions, significant pressure losses appear in the test section, what leads to significant errors in measured data. Regarding the possible ways of tunnel reconstruction, we examined three different possibilities of changing the test section configurations: an increase of the test section height, displacement of the airfoil below the tunnel centreline and, finally, introduction of divergent test section walls. It was shown that neither the use of higher test section, nor the change of the airfoil location, gives any significant improvement in reference to the existing tunnel configuration. Only after divergent test section walls were introduced, the distributions of pressure coefficient became well consistent with their expected values.

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Authors and Affiliations

Witold Selerowicz
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Abstract

Axial piston pumps with constant pressure and variable flow have extraordinary possibilities for controlling the flow by change of pressure. Owing to pressure feedback, volumetric control of the pump provides a wide application of these pumps in complex hydraulic systems, particularly in aeronautics and space engineering. Mathematical modeling is the first phase in defining the conception of a design and it has been carried out at the beginning of the project. Next very important phase is the check-out of the characteristics at the physical model when the pump has been produced. Optimal solution to the hydropump design has been reached by thorough analysis of the parameters obtained at the physical model by means of the simulation results of the mathematical model. The paper presents the possibilities for selecting the most influential parameters, their correction for certain values, and eventually the simulation at the mathematical model which shows the change of hydropump performances. After all these analyses, appropriate changes are made in design documentation which will serve for prototype production. Finally, when all kinds of tests are done at the prototypes along with fine adjustment of design solution, the series production of hydropump will be organized.

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Authors and Affiliations

Radovan Petrović
Andrzej Banaszek
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Abstract

A crucial feature in health monitoring of already existing structures is to be seen particularly in identifying their topical internal structural parameters and controlling their remaining bearing capacity in the course of ageing processes. This is commonly carried out by measuring the deformations/strains caused by test-loading and calculating the parameters on the basis of the metered data.

In the case of elastic response of materials, the information on the parameters is directly related to the time of measurement; in the case of visco-elastic response, however, the history of the time-depending structural response during the period between initial loading and initiating the test-measurements is generally unknown. The problem exists, then, to separate the superimposed strains due to the existing state and to the test-load. For solving the problem, at first the relevant relations between stress/strain and the visco-elastic parameters are considered. Then a procedure will be described how to determine the strain state owing to the test-load only and to calculate the relevant parameters as functions of time. According to the principle of time-shift invariance, the results describe the time-depending response of the viscoelastic material, no matter at which time the loads are applied.

The presented method will be illustrated by two simple but instructive examples.

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Authors and Affiliations

Karl-Hans Laermann
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Abstract

Pressure pulsations occurring in volumetric compressors manifold are still one of the most important problems in design and operation of compressor plants. The resulting vibrations may cause fatigue cracks and noise. Accuracy of the contemporary method is not sufficient in many cases. The methods for calculating pressure pulsation propagation in volumetric compressors manifolds are based on one-dimensional models. In one-dimensional models, the assumption is made that any installation element may be simplified and modeled as a straight pipe with given diameter and length or as a lumped volume. This simplification is usually sufficient in the case of small elements and long waves. In general, the geometry of the element shall be also considered. This may be done using two ways: experimental measurements of pressure pulsations, which lead to transmittance approximation for the investigated element, or CFD analysis and simulation for the acoustic manifold element. In this paper, a new method based on Computational Fluid Dynamics (CFD) simulation is presented. The main idea is to use CFD simulation instead of experimental measurements. The impulse flow excitation is introduced as a source. The results of simulation are averaged in the inlet and outlet cross sections, so time only dependent functions at the inlet and outlet of the simulated element are determined. The transmittances of special form are introduced. On the basis of introduced transmittances, the generalized four pole matrix elements and impedance matrix elements may be calculated. The method has been verified on the basis of experimental measurements.

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Authors and Affiliations

Piotr Cyklis
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Abstract

This paper presents an idea and results of 2D and 3D numerical CFD simulations of the proposed ring-engine construction dedicated for air propulsion or generation of electric power. The engine is designed as the simplest construction realizing the idea of pulsating reaction chamber utilizing a constant volume combustion principle. An atypical fuel (hydrogen peroxide) is used in the analyzed construction. The proposed ring-engine has reaction chambers forming a part of a ring periodically filled by cooling air and hydrogen peroxide vapour. The H2O2 is decomposed in exothermic reaction increasing pressure inside the chamber of constant volume. High pressure gas contents of the reaction chambers are periodically decompressed by jet nozzles generating torque. The paper contains the description of the ring-engine idea, the schematic engine geometry and a set of data visualizing pressure, velocity, temperature and species distribution inside the engine components being results of numerical simulations.

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Authors and Affiliations

Janusz Piechna

Editorial office

Editor-in-Chief

Prof. Marek Wojtyra, Warsaw University of Technology, Poland

 

Editorial Board

Prof. Krzysztof Arczewski, Warsaw University of Technology, Poland

Prof. Janusz T. Cieśliński, Gdańsk University of Technology, Poland

Prof. Antonio Delgado, LSTM University of Erlangen-Nuremberg, Germany

Prof. Peter Eberhard, University of Stuttgart, Germany

Prof. Jerzy Maciej Floryan, The University of Western Ontario, Canada

Prof. Janusz Frączek, Warsaw University of Technology, Poland

Prof. Zbigniew Kowalewski, Institute of Fundamental Technological Research, Polish Academy of Sciences, Poland

Prof. Zenon Mróz, Institute of Fundamental Technological Research, Polish Academy of Sciences, Poland

Prof. Andrzej J. Nowak, Silesian University of Technology, Poland

Dr. Andrzej F. Nowakowski, The University of Sheffield, United Kingdom

Prof. Jerzy Sąsiadek, Carleton University, Canada

Prof. Jacek Szumbarski, Warsaw University of Technology, Poland

Prof. Tomasz Wiśniewski, Warsaw University of Technology, Poland

Prof. Günter Wozniak, Chemnitz University of Technology, Germany

 

Assistant to the Editor

Małgorzata Broszkiewicz, Warsaw University of Technology, Poland

 

Editorial Advisory Board

Prof. Alberto Carpinteri, Politecnico di Torino, Italy

Prof. Fernand Ellyin, University of Alberta, Canada

Prof. Feng Gao, Shanghai Jiao Tong University, P.R. China

Prof. Emmanuel E. Gdoutos, Democritus University of Thrace, Greece

Prof. Gregory Glinka, University of Waterloo, Ontario, Canada

Prof. Andrius Marcinkevicius, Vilnius Gedeminas Technical University, Lithuania

Prof. Manuel José Moreira De Freitas, Instituto Superior Tecnico, Portugal

Prof. Andrzej Neimitz, Kielce University of Technology, Poland

Prof. Thierry Palin-Luc, Arts et Métiers ParisTech, Institut Carnot Arts, France

Prof. Andre Pineau, Centre des Matériaux, Ecole des Mines de Paris, France

Prof. Narayanaswami Ranganathan, LMR, Ecole Polytechnique de l'Université de Tours, France

Prof. Jan Ryś, Cracow University of Technology, Poland

Prof. Adelia Sequeira, Technical University of Lisbon, Portugal,

Prof. Józef Szala, University of Technology and Life Sciences in Bydgoszcz, Poland

Prof. Edmund Wittbrodt, Gdańsk University of Technology, Poland

Prof. Jens Wittenburg, Karlsruhe Institute of Technology, Germany

Prof. Stanisław Wojciech, University of Bielsko-Biała, Poland

 

Language Editor

Lech Śliwa, Institute of Physiology and Pathology of Hearing, Warsaw, Poland

  

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ARCHIVE OF MECHANICAL ENGINEERING

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Instructions for authors

About the Journal
Archive of Mechanical Engineering is an international journal publishing works of wide significance, originality and relevance in most branches of mechanical engineering. The journal is peer-reviewed and is published both in electronic and printed form. Archive of Mechanical Engineering publishes original papers which have not been previously published in other journal, and are not being prepared for publication elsewhere. The publisher will not be held legally responsible should there be any claims for compensation. The journal accepts papers in English.

Archive of Mechanical Engineering is an Open Access journal. The journal does not have article processing charges (APCs) nor article submission charges.

Original high quality papers on the following topics are preferred:

  • Mechanics of Solids and Structures,
  • Fluid Dynamics,
  • Thermodynamics, Heat Transfer and Combustion,
  • Machine Design,
  • Computational Methods in Mechanical Engineering,
  • Robotics, Automation and Control,
  • Mechatronics and Micro-mechanical Systems,
  • Aeronautics and Aerospace Engineering,
  • Heat and Power Engineering.

All submissions to the AME should be made electronically via Editorial System - an online submission and peer review system at: https://www.editorialsystem.com/ame

More detailed instructions for Authors can be found there.

Open Access policy

Archive of Mechanical Engineering jest czasopismem wydawanym w wolnym dostępie na licencji CC BY-NC-ND 4.0. https://creativecommons.org/licenses/by-nc-nd/4.0/

Archive of Mechanical Engineering is an open access journal with all content available with no charge in full text version. The journal content is available under the licencse CC BY-NC-ND 4.0 https://creativecommons.org/licenses/by-nc-nd/4.0/.

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