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1
Content available Rotorcraft thickness noise control
Szulc O.
Archives of Mechanics
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2021
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Vol. 73, nr 4
391--417
EN
The paper describes an innovative idea of Thickness Noise Control (TNC) based on adoption of a flow control strategy (i.e. surface ventilation) for acoustic attenuation of helicopter rotor periodic noise. The TNC method is relying on incorporation of multiple cavities (closed by perforated panels and linked to low- and high-pressure reservoirs) located in a symmetrical manner at front and rear portions of the blade tip. The efficiency of the new approach is verified using a two-bladed model rotor of Purcell (untwisted variant of the blade of Bell UH-1H Iroquois helicopter) in low-thrust hover conditions. The results of numerical simulations, obtained with CFD solver (Spalart–Allmaras turbulence and Bohning–Doerffer transpiration models), indicate that in the near-field of the blade tip, both the amplitude and spectral contents of pressure impulses of emitted thickness noise are significantly improved. The TNC method, in the proposed unsteady mode of operation, turns out to be a suitable means of thickness noise reduction in forward flight. Moreover, it is demonstrated that by proper azimuthal activation the efficiency is almost unaltered, while the rotor torque penalty and required transpiration mass-flux are decreased by a factor of 3–5 compared to a steady arrangement.
2
Content available Numerical analysis of high-speed impulsive (HSI) noise of PZL W3-A "Sokół" (Falcon) helicopter main rotor in forward flight
Szulc O., Doerffer P., Tejero F., Żółtak J., Małecki J.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2015
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Vol. 19, No 2
181--196
EN
The paper presents the results of a numerical simulation of the flow and acoustic field generated by the PZL W3-A “Sokół” (Falcon) helicopter main roto in high-speed forward flight conditions based on the URANS approach and the chimera overlapping grids technique. A refined CFD model (40+ million of control volumes, 600+ blocks chimera mesh) was designed to resolve the flow-field together with the low-frequency content of the acoustic pressure spectrum in the near-field of the rotor blades to allow high-speed impulsive (HSI) noise prediction. Detailed 3D data was recorded for one rotor revolution (approx. 3 TB) allowing exceptional insight into the physical mechanisms initiating the occurrence and development of the HSI noise phenomenon.
3
Content available remote Time-accurate simulation of flow past PZL W-3A "Sokół" (Falcon) helicopter main rotor in forward flight
Szulc O., Doerffer P., Żółtak J., Małecki J.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2013
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Vol.17, No 1-2
43--61
EN
The paper presents the results of numerical simulations based on the URANS approach and the chimera overlapping grids technique of the main PZL W-3A "Sokół" (Falcon) helicopter rotor in forward flight conditions. The low-speed flight case models the helicopter rotor as parallel to the ground keeping forward speed of approximately 99km/h. Strong Blade-Vortex Interaction (BVI) is responsible for a high level of vibration and noise. The high-speed (266km/h) case reveals two main problems of modern helicopters: compressibility effects due to strong shock-wave boundary layer interaction on the advancing side and separation leading to a dynamic stall on the retreating side of the rotor. An attempt is made to correlate the results of the simulations with the very limited flight test data.
4
Content available Modelowanie pionowych drgań łopat śmigłowca w systemie CATIA V5
Kania M.
Postępy Nauki i Techniki
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2011
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nr 7
94-101
PL
Zjawisko drgań układów mechanicznych jest istotnym problemem w projektowaniu części maszyn i mechanizmów. Szczególne ważne jest to w urządzeniach takich ja śmigłowce, w których nie można sobie pozwolić na awarię. Za pomocą modułów DMU Kinematics oraz Knownage Advisor w systemie Catia V5 został stworzony model drgań łopaty wirnika nośnego śmigłowca w układzie klasycznym. W tym modelu zostały odtworzone więzy kinematyczne występujące na rzeczywistym obiekcie oraz dodany opis równań ruchu łopaty w trzech kierunkach, to jest w płaszczyźnie ciągu, obrotów i przekręceń. Model ten pozwala na analizę zachowania się łopat przy różnych wymuszeniach, analizę maksymalnych wychyleń od położenia neutralnego oraz zbadanie zachowania się układu przy różnych wymiarach części składowych mechanizmu.
EN
In this publication presents virtual vibration model of helicopter main rotor blade, created in modules DMU Kinematics and Knownage Advisor in Catia V5 system. In this model create all kinematic joints based on real object. This method of modeling allow to analyzing blade vibration with parameters of motion defined by user.
5
Content available remote Measurement of a Helicopter Main Rotor Composite Blade
Skalski P., Parafiniak M.
Machine Dynamics Research
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2011
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Vol. 35, No. 4
105-110
EN
The research presented in this paper focuses on a composite structure test. The object of the investigation is a blade from main rotor of the IS-2 helicopter. The basic methodology which is used is the Experimental Modal Analysis (EMA). The EMA technique is an established tool for the identification of dynamic properties of structure. Based on the experimental data collection, dynamic properties of a research object were estimated. The modal parameters have been estimated using PolyMAX - module of LMS Test.Lab software.
6
Content available remote Numerical Simulation of Model Helicopter Rotor in Hover
Doerffer P., Szulc O.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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2008
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Vol. 12, No 3-4
227-236
EN
The article presents details of a URANS simulation of the flow field near a hovering model of the Caradonna and Tung (1981) helicopter rotor [1]. The CFD code SPARC [2] proves to be capable of capturing the aerodynamics of a two-bladed rotor in high-speed transonic hover conditions. A comparison of the simulation results with the experimental data is acceptable, hence the described methodology might be used with confidence in future numerical studies of application of noise-reducing devices on helicopter blades.
7
Content available remote Application of neural network to detecting faults of helicopter rotor.
Stanisławski J.
Archive of Mechanical Engineering
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2005
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Vol. LII, nr 2
135-155
EN
The paper presents the possibilities of neural network application in recognition of rotor blade faults. Computer calculated data of rotor response due to faults were used for neural network training. The rotor was modeled by elastic axes with distribution of lumped masses. The rotor defects were simulated by changing aerodynamic, inertial or stiffness properties of one of the blades. Time results were subjected to spectral analysis for the purpose of neural networks training.
PL
Przedstawiono możliwości zastosowania sieci neuronowych do rozpoznawania usterek łopat wirnika nośnego śmigłowca. Do treningu sieci neuronowych wykorzystano obliczeniowe dane uwzględniające zmianę obciążeń łopat i głowicy przy symulowanych uszkodzeniach. W modelu fizycznym łopaty wirnika reprezentowały osie sprężyste z dołączonym układem mas skupionych. Uszkodzenia wirnika symulowano poprzez zmianę wybranych własności aerodynamicznych, masowych lub sztywnościowych łopat.
8
Content available remote Drgania skrętne wirnika śmigłowca
Świder A.
Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika
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1999
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z. 52 [174]
239-244
EN
In the paper mathematical models of helicopter rotor with articulated blades torsional vibrations are presented. The formulas for rotor natural frequencies as a function of number of blades were elaborated. In the Matlab-Simulink environment simulation models were composed and, with their help, free and forced non-stationary vibrations were investigated.
9
Content available Transonic flows, shock wave-turbulent boundary layer interaction
Doerffer P., Kaczyński J.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
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1998
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Vol. 2, No 2
271-286
EN
Shock wave-boundary layer interaction is one of the most important phenomenon in transonic flows. Due to its complexity it is difficult as well for experimental as for numerical study. The growing potential of CFD is therefore of great importance. Different aspects of shock wave-boundary layer interaction should be studied in different flow configurations. Therefore results concerning profile flow, helicopter rotor at hovering and forward flight and internal flows are presented in this paper. These are to illustrate our ability in CFD in general. Besides flow simulation the development of codes is carried out.
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