Temat: model test - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Experimental analysis of the helicopter ditching
Autorzy:: Kraskowski, Marek
Tematy:: rotorcraft
helicopter
ditching
scale model test; Pokaż więcej
Wydawca:: Akademia Marynarki Wojennej. Wydział Dowodzenia i Operacji Morskich
Powiązania:: https://bibliotekanauki.pl/articles/1810600.pdf Link otwiera się w nowym oknie
Opis:: The paper presents the method and results of the model tests of helicopter ditching, aimed at adaptation of the helicopter's construction for marine mis-sions. The experiment, realized by Maritime Advanced Research Centre S.A. (CTO) required elaboration of dedicated measurement stand, and solving a number of specific technical problems resulting from the necessity of assuring the repeatability, and required accuracy of the measurements and scalability of the results. Such kind of experiment is not a standard task of a hydrodynamic model testing institution, so it brings an innovation in the testing methodology. The paper presents the details of the test stand and the model itself with rotating rotor, design of the experiment, as well as an overview of the results and main conclusions.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Experimental evaluation of forward speed effect on maneuvering hydrodynamic derivatives of a planing hull
Autorzy:: Kazerooni, M. F.
Seif, M. S.
Tematy:: planing hull
maneuvering
model test
derivative
hydrodynamic; Pokaż więcej
Wydawca:: Akademia Morska w Szczecinie. Wydawnictwo AMSz
Powiązania:: https://bibliotekanauki.pl/articles/135366.pdf Link otwiera się w nowym oknie
Opis:: The calculation of unknown hydrodynamic derivatives of the equations of motion is the first step to estimate ship maneuverability and dynamic stability. These derivatives can be obtained theoretically, experimentally and numerically. Despite the development of the oblique towing model test to measure the hydrodynamic derivatives of displacement ships, limited experimental results are available for hydrodynamic derivatives of high speed crafts and speed dependency of the hydrodynamic derivatives is not understood well. In this paper a systematic series of model tests is described to determine the effect of forward speed on hydrodynamic derivatives of a monohull planing craft and the variations of the hydrodynamic derivatives by forward speed are derived. According to the results, hydrodynamic derivatives of planing hull are dramatically changed by variations of forward speed. Moreover, it is not possible to introduce a constant hydrodynamic derivative in the all the ranges of drift angle. Thus, the method of known constant hydrodynamic derivatives is not applicable to the simulation of planing craft maneuvering and variable hydrodynamic derivatives should be applied.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Test studies of the resistance and seakeeping performance of a trimaran planing hull
Autorzy:: Ma, W.
Sun, H.
Zou, J.
Zhuang, J.
Tematy:: trimaran planing hull
appendix
resistance
seakeeping
model test; Pokaż więcej
Wydawca:: Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Powiązania:: https://bibliotekanauki.pl/articles/259495.pdf Link otwiera się w nowym oknie
Opis:: Towing tank tests in calm water were performed on a trimaran planing hull to verify its navigational properties with different displacements and centres of gravity, as well as to assess the effects of air jets and bilge keels on the hull’s planing capabilities, and to increase the longitudinal stability of the hull. Hydrostatic roll tests, zero speed tests, and sea trials in the presence of regular waves were conducted to investigate the hull’s seakeeping ability. The test results indicate that the influence of the location of the centre of gravity on the hull resistance is similar to that of a normal trimaran planing hull; namely, moving the centre of gravity backward will reduce the resistance but lower the stability. Bilge keels improve the longitudinal stability but slightly affect the resistance, and the presence of air jets in the hull’s channels decreases the trim angle and increases heaving but has little effect on the resistance. Frequent small-angle rolling occurs in waves. The heaving and pitching motions peak at the encounter frequency of , and the peaks increase with velocity and move towards greater encounter frequencies. When the encounter frequency exceeds, the hull motion decreases, which leads to changes in the navigation speed and frequency.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Effective width rule in the analysis of footing on reinforced sand slope
Autorzy:: Abdi, Abdelmadjid
Abbeche, Khelifa
Athmania, Djamel
Bouassida, Mounir
Tematy:: bearing capacity
eccentricity
footing
geogrid
model test
slope; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/178217.pdf Link otwiera się w nowym oknie
Opis:: This paper presents the results obtained from an experimental programme and numerical investigations conducted on model tests of strip footing resting on reinforced and unreinforced sand slopes. The study focused on the determination of ultimate bearing capacity of strip footing subjected to eccentric load located either towards or opposite to the slope facing. Strip footing models were tested under different eccentricities of vertical load. The obtained results from tests conducted on unreinforced sand slope showed that the increase in eccentricity of applied load towards the slope facing decreases the ultimate bearing capacity of footing. Predictions of the ultimate bearing capacity obtained by the effective width rule are in good agreement with those proposed from the consideration of total width of footing subjected to eccentric load. The ultimate bearing capacity of an eccentrically loaded footing on a reinforced sand slope can be derived from that of axially loaded footing resting on horizontal sand ground when adopting the effective width rule and the coefficient of reduction due to the slope. When increasing the distance between the footing border to the slope crest, for unreinforced and reinforced ground slope by geogrids, the ultimate bearing capacity of footing is no more affected by the slope ground.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Model tests on characteristic of suction caissons in saturated fine sand under intermittent loading
Autorzy:: Shi, P.
Tematy:: intermittent suction installation
model test
sand
suction caisson; Pokaż więcej
Wydawca:: Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Powiązania:: https://bibliotekanauki.pl/articles/258534.pdf Link otwiera się w nowym oknie
Opis:: Suction caissons are often used for the caissons of both offshore oil platforms and offshore wind power projects because of their advantages of simple construction, economical cost, and reusability. In this study, model tests were conducted in sand in order to investigate the effects of the caisson installation method on the penetration depth and the critical suction. Results of the test program showed that the method of changing the frequency of suction during different stages of the process can increase the penetration depth of the caisson. Combining with the deformation of the soil body inside and outside the caisson, the existing method for calculating the critical suction is modified, and the critical suction calculation equation of the discontinuous penetration test is proposed. Based on the test results, the calculation equation of the soil heave height can be more accurate predicted. The analysis results verify that the calculation method and the actual results are in good agreement.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Numerical and experimental study on seakeeping performance of a high-speed trimaran with T-foil in head waves
Autorzy:: Li, Ang
Li, Yunbo
Tematy:: trimaran
T-foil
URANS
longitudinal motion
model test; Pokaż więcej
Wydawca:: Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Powiązania:: https://bibliotekanauki.pl/articles/258842.pdf Link otwiera się w nowym oknie
Opis:: 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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Model investigation of piston ring-cylinder liner collaboration on a high power engine
Autorzy:: Serdecki, W.
Krzymień, P.
Tematy:: marine combustion engine
piston ring
oil film
model test; Pokaż więcej
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Powiązania:: https://bibliotekanauki.pl/articles/245364.pdf Link otwiera się w nowym oknie
Opis:: Failures caused by improper collaboration between piston ring and cylinder liner still happen on engines ofhigh output, marine ones in particular. Among causes of this phenomenon one can mention higher mechanical and thermal loads of crank mechanism as well as difficulties in supply and distribution of lubricating oil over the entire surface of cylinder liner. It would be extremely difficult and because of regulations in most cases impossible to perform tests on correct collaboration between rings and liner of real running engine and on the other hand such tests on a test stand would be quite expensive. Use of mathematical models and tests on simulation model stands offers a way to reduce these costs. Basic dependences connecting piston ring geometry with oil film parameters and introductory results of computations performed with the use of analytical model of test stand will be presented in this paper. The tests are to be carried out for ring geometry corresponding to that of marine engine rings. Due to that, using presented earlier formulas and computer program constructed by the authors the phenomena accompanying operation of different versions of rings were analyzed from the point of oil film thickness and generated friction losses. These ring versions which revealed the most advantageous properties will be made and tested on a test stand.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Motion prediction of catamaran with a semisubmersible bow in wave
Autorzy:: Sun, H.
Jing, F.
Jiang, Y.
Zou, J.
Zhuang, J.
Ma, W.
Tematy:: SSB catamaran
model test
overset grid
motion region
motion response; Pokaż więcej
Wydawca:: Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Powiązania:: https://bibliotekanauki.pl/articles/258596.pdf Link otwiera się w nowym oknie
Opis:: Compared with standard vessels, a slender catamaran with a semi-submerged bow (SSB) demonstrates superior seakeeping performance. To predict the motion of an SSB catamaran, computational fluid dynamics methods are adopted in this study and results are validated through small-scale model tests. The pitch, heave, and vertical acceleration are calculated at various wavelengths and speeds. Based on the overset grid and motion region methods, this study obtains the motion responses of an SSB catamaran in regular head waves. The results of the numerical studies are validated with the experimental data and show that the overset grid method is more accurate in predicting the motion of an SSB catamaran; the errors can be controlled within 20%. The movement data in regular waves shows that at a constant speed, the motion response initially increases and then decreases with increasing wavelength. This motion response peak is due to the encountering frequency being close to the natural frequency. Under identical sea conditions, the motion response increases with the increasing Froude number. The motion prediction results, that derive from a shortterm irregular sea state, show that there is an optimal speed range that can effectively reduce the amplitude of motion.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Test research on the resistance performance of high-speed trimaran planing hull
Autorzy:: Ma, W.
Sun, H.
Zou, J.
Yang, H.
Tematy:: trimaran planing hull
side hulls
high speed
step
resistance
model test; Pokaż więcej
Wydawca:: Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Powiązania:: https://bibliotekanauki.pl/articles/259708.pdf Link otwiera się w nowym oknie
Opis:: In order to identify high-speed navigation ability of trimaran planing hull, as well as investigate the characteristics of its resistance and hull form, ship model tests were conducted to measure resistance, trim and heaving under different displacements and gravity centre locations. The test results were then used to study the influence of spray strips on resistance and sea-keeping qualities. Moreover, different planning surfaces were compared in the model tests which helped to look into influence of steps on hull resistance and its moving position. Also, the resistance features of monohull and trimaran planing hulls, both with and without steps, were compared to each other. From the tests it can be concluded that: the two auxiliary side hulls increase aerodynamic lift at high-speed motion, which improves the hydrodynamic performance; the trimaran planing hull has also excellent longitudinal stability and low wave-making action; when Fr∇> 8, its motion is still stable and two distinct resistance peaks and two changes of sailing state (the second change is smaller) appear; spray strips are favourable for sea-keeping qualities at high speed. The change trends before the second resistance peak as to the resistance and sailing behaviour of trimaran planing hull without steps are the same as for monohull planing hull without steps. but when steps in both hulls exist the change trends are different; more specifically: trimaran planing hull with steps has only one resistance peak and its resistance increases along with its speed increasing, and the resistance is improved at the increasing speed as the number of steps increases.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Model experiments to assess effect of cavities on bearing capacity of two interfering superficial foundations resting on granular soil
Autorzy:: Saadi, Djamel
Abbeche, Khelifa
Boufarh, Rafik
Tematy:: bearing capacity
shallow foundation
cavity
interference effect
model test
granular soil; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/1845136.pdf Link otwiera się w nowym oknie
Opis:: The objective of this paper is to describe the effect of cavities on the bearing capacity of two interfering footings based on granular soil using an exclusively experimental approach with a test model designed in the laboratory. The experimental protocol was carried out based on the variation of several parameters such as the spacing (x) (axis to axis) between the footings, and the distance (H) between the footings and cavities and between the cavities axes (L). The results highlight the effect of cavities and the interference of two strip footings on the bearing capacity factor (q) and efficiency factor (EF). Moreover, the results revealed that, in the case wherein the distance between the footings and the cavity is greater than 3, the cavity impact is eliminated.
Dostawca treści:: Biblioteka Nauki

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