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1
Content available Numerical modelling of sound transmission through the window type partition
Kwapisz L., Maurin A., Jakubowski P.
Vibrations in Physical Systems
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2016
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Vol. 27
211--218
EN
The approach to numerical modelling of sound transmission through window type partitions is investigated in the paper. The laboratory conditions of reverberation room are simulated. The numerical and experimental results are compared. The impact of different model parameters on the sound insulation levels are evaluated.
2
Content available remote Free vibrations analysis of shrouded bladed discs with one loose blade
Rządkowski R., Kwapisz L., Drewczyński M., Szczepanik R., Rao J.S.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2006
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Vol. 10, No 1
83-95
EN
As a failure of rotor blades in a gas turbine was reported, the rotating-mode shapes of flexible shrouded bladed disc assemblies were calculated using a finite element approach. Rotational effects, such as centrifugal stiffening were accounted for, and all couplings between the flexible parts were allowed. The spin softening effects were neglected. A dynamic analysis of the shrouded bladed disc demonstrated that it was designed with a sufficient safety region of resonance. In case of one blade getting loose, it is vibrating in resonance.
3
Content available remote Unsteady Forces Acting on Blades and the Shaft in the Last Stage of Steam Turbine with Exhaust Hood
Rządkowski R., Soliński M., Kwapisz L., Gnesin V.
Zeszyty Naukowe. Cieplne Maszyny Przepływowe - Turbomachinery / Politechnika Łódzka
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2005
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nr 128, vol. 2
471-478
EN
The aerodynamic unsteady forces acting on the rotor blades and the shaft in the last stage of turbine 13K215 were calculated. A numerical simulation of a 3D transonic ideal gas flow through turbomachinery blade rows moving relative to one another is presented, with a non-uniform pressure distribution of steam behind the rotor blades. In order to find the pressure distribution, numerical calculations were done for unsteady flow through the stage with the exhaust hood using the program FLUENT. The unsteady forces of the rotor blades were calculated. The natural frequencies of the bladed disc were compared with the frequencies of the flow excitations. Next, the unsteady forces acting on the shaft were calculated, taking the mistuning of the blades into consideration.
4
Content available remote Strength analysis of penstock bifurcations in hydropower plants
Adamkowski A., Kwapisz L.
Transactions of the Institute of Fluid-Flow Machinery
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2004
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nr 115
113-124
EN
The strength analysis of penstock bifurcation in hydropower plants is discussed in the present paper. The analysis consists of determining the maximal internal pressure, (e.g. during turbine load rejection), stress analysis of the pipeline shell for assumed loading and assumed or determined material properties. The investigation results can be helpful when determining the proper rate of the flow cut-off and recommending the strengthening precautions to be applied in places of maximum stress concentration in order to prevent future penstock ruptures.
5
Content available remote Influence of the blade length on natural frequencies and modes shapes of two bladed rigid discs on the shaft
Sokołowski J., Rządkowski R., Kwapisz L.
Transactions of the Institute of Fluid-Flow Machinery
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2003
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nr 114
177-190
EN
The dynamic behaviour of a rotor consisting of two bladed discs on a solid shaft is considered. The effect of shaft flexibility on the dynamic characteristics of the bladed discs and the coupling effects between the shaft and bladed disc modes are investigated. Results presented for various cases with differing blades flexibility show cleary the coupling effects in a bladed disc-shaft system. Calculated natural frequencies obtained from blade, shaft, bladed disc and shaft with two discs are checked to discover resonance conditions and the coupling effects. The calculations show the influence of the shaft on the natural frequencies of the bladed discs up to one nodal diameter frequencies. The torsional frequency of the shaft with two discs is coupled with the zero nodal diameters modes of the single bladed discs. The bending modes of the shaft are coupled with one nodal diameter modes of the bladed discs. It is shown that including the shaft in the bladed discs model is important from the designer's point of view and can change the spectrum of frequencies considerably.
6
Content available remote Frequencies and modes of rotating flexible shrouded bladed discs-shaft assemblies
Sokołowski J., Rządkowski R., Kwapisz L.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2003
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Vol. 7, No 2
215-231
EN
It is now increasingly necessary to predict accurately, at the design stage and without excessive computing costs, the dynamic behaviour of rotating parts of turbomachines, so that resonant conditions at operating speeds are avoided. In this study, global rotating mode shapes of flexible shrouded bladed disc-shaft assemblies are calculated. The rotating modes have been calculated by using a finite element cyclic symmetry approach. Rotational effects, such as centrifugal stiffening have been accounted for, and all the possible couplings between the flexible parts have been allowed. Gyroscopic effects have been neglected. The numerical results have been compared with the experimental. The calculations show the influence of shaft flexibility on the natural frequencies of shrouded bladed discs up to four nodal diameters for the two first frequencies series.
7
Content available remote Free vibrations of bladed disc on the shaft
Kwapisz L., Sokołowski J., Rządkowski R.
Archives of Civil Engineering
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2003
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Vol. 49, nr 3
321-331
EN
It is now increasingly necessary to predict accurately, at the design stage the dynamic behaviour of rotating parts of turbomachines, so that resonant conditions at operating speeds. In this study, the global rotating mode shapes of flexible shrouded bladed disc-shaft assemblies are calculated. The rotating modes are calculated by using a finite element cyclic symmetry approach. Rotational effects, such as centrifugal stiffening are accounted for, and all the possible couplings between the flexible parts are allowed. The gyroscopic effects are neglected. The numerical results were compared with the experimental. The calculation shows the influence of the shaft on the natural frequencies of the shrouded bladed discs.
PL
W celu uniknięcia rezonansu przy różnych prędkościach obrotowych, występuje konieczność pełnego modelowania wirujących części turbozespołów. W niniejszej pracy przedstawiono obliczenia częstotliwości i postaci drgań podatnej ułopatkowanej tarczy osadzonej na fragmencie wału. Analizę numeryczną przeprowadzono przy użyciu cyklicznej symetrii w metodzie elementów skończonych. Uwzględniono usztywnienie konstrukcji pod wpływem siły odśrodkowej oraz wszystkie możliwe sprzężenia pomiędzy elementami układu. Efekty żyroskopowe zostały pominięte. Wyniki obliczeń numerycznych zostały porównane z wynikami eksperymentalnymi. Przedstawione obliczenia pokazują duży wpływ wału na niektóre częstotliwości ułopatkowanej tarczy wirnikowej, co może mieć znaczenie w pracach projektowych.
8
Content available remote Free vibration of two bladed discs on the shaft
Kwapisz L, Sokołowski J., Rządkowski R.
Vibrations in Physical Systems
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2002
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Vol. 20
206--207
9
Content available Application of underwater hydroacoustic navigation system in the research of submerged cables and ROV umbilicals
Narewski M., Kwapisz L., Rowiński L. A., Żrodowski C.
Hydroacoustics
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1997
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Vol. 1
243--248
EN
There is several algorythms known for a computer simulation of tethers used in underwater vehicles. The results of research done for specific conditions are hardly available. Practically, there is a very limited number of data available for comparision of various calculation algorythms. The described profect was directed on comparison of analytical and experimental results of the sumberged cables behaviour subjected to 3-D water flow. Experimental data were obtained in a part during tests of cable models in circular water tank. Real sea condition measurements done at full scale with ROV and underwater towed vehicles were done to compare data from test tank with reality. Sumerged cable cooridnates were obtained using super short baseline u/w navigation system. Forces inducted in the tethers were also measured using spectal measurement methods. The paper describes major problems encountered during use of the ORE LXT u/w navigation system and summarises experience with real underwater systems used in the research.
10
Content available A measurement of 3-D water velocity components during ROV tether simulations in a test tank using hydroacoustic doppler velocimeter
Kwapisz L., Narewski M., Rowiński L. A., Żrodowski C.
Hydroacoustics
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1997
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Vol. 1
231--236
EN
A computer simulation of ROV tethers performance could be done more precisely if velocity field of water flowing around the tether cable is known. The paper describes operation and performance of the doppler acoustic velocimeter ADVlab. A brief outline of the procedures and related problems with determination of 3-D velocity components in the test tank is described.
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