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Wyświetlanie 1-15 z 16
Tytuł:
Experimental Study of the Explosion of Aluminized Explosives in Air
Autorzy:
Chen, Y.
Xu, S.
Wu, D. J.
Liu, D. B.
Powiązania:
https://bibliotekanauki.pl/articles/358676.pdf
Data publikacji:
2016
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
explosion in air
aluminized explosives
boron powders
TNT equivalence
fireballs
Opis:
Piezoelectric gauges were used to measure the shock wave overpressure of aluminized explosives and of a TNT charge. An infrared thermal-imaging spectrometer was used to collect the infrared signatures produced by the explosion fireball when the examined explosives were detonated. The measurement of the infrared signatures was used to estimate the surface temperatures and the dimensions of the fireball. Two aluminized explosive compositions (RDX/Al/AP and RDX/Al/B/AP) have been analyzed. 500 g charges of the aluminized explosives were prepared and studied, and their TNT equivalences were calculated according to the experimental data and the explosion law. The highest surface temperatures of the fireballs of these aluminized explosives were up to 1600 °C, which was higher than that of the TNT charge. In the region of the highest surface temperature above 700 °C, the duration for the composition RDX/Al/AP was about 232 ms (2.73 times more than TNT), whilst RDX/Al/B/AP was about 360 ms. The fireballs obtained from the explosion of these aluminized explosives had larger dimensions than that of TNT, especially when the surface temperature was above 1000 °C. The test results indicate that the addition of boron powders to aluminized explosives is a good way to enhance their blast effect, to improve the temperature of the explosion field and to prolong the duration of the higher temperature.
Źródło:
Central European Journal of Energetic Materials; 2016, 13, 1; 117-134
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Accurate measurements and establishment of a model of the mechanical properties of dried corn kernels
Autorzy:
Feng, J.
Wu, Z.
Qi, D.
Jin, Y.
Wu, W.
Powiązania:
https://bibliotekanauki.pl/articles/2082547.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
thin layer drying
corn kernel
mechanical property
model
Opis:
Mechanical drying significantly affects the mechanical properties of corn kernels. Improper drying may result in material losses and in a decline in quality due to pressure, collisions, and other factors during subsequent storage and transport operations. A literature survey revealed that at time of writing the characteristics of dried corn kernels have not been systematically and fully studied. In this paper, an orthogonal rotation combination test scheme was designed. Using a multiparameter controllable thin layer drying test bench, corn was dried under different conditions (temperature 30-60°C, relative humidity 30-60%, air velocity 0.46-0.94 m s–1, initial moisture content of corn of 20-30% w.b., tempering ratio 0-3). Then, a texture analyser was used to measure the mechanical properties (rupture force, rupture energy, modulus of elasticity and brittleness) of the dried corn kernels. Relationship models were established for the rupture force, rupture energy, modulus of elasticity and brittleness and drying conditions of corn kernels. An increase in the drying temperature from 30 to 60°C increased the rupture energy, elastic modulus, and brittleness of the corn kernels by 19.11, 11.76, and 4.02%, respectively; an increase in the drying relative humidity from 30 to 60% increased the rupture force, energy, modulus of elasticity and brittleness by 15.07, 13.74, 20.73, and 3.31%, respectively.
Źródło:
International Agrophysics; 2019, 33, 3; 373-381
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Lifting Wavelet Domain Audio Watermarking Algorithm Based on the Statistical Characteristics of Sub-Band Coefficients
Autorzy:
Tao, Z.
Zhao, H.
Wu, J.
Gu, J.
Xu, Y.
Wu, D.
Powiązania:
https://bibliotekanauki.pl/articles/177956.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
audio watermarking
lifting wavelet transform
statistical characteristics
sub-band coefficients
Opis:
In this paper, a new lifting wavelet domain audio watermarking algorithm based on the statistical characteristics of sub-band coefficients is proposed. First of all, an original audio signal was segmented and each segment was divided into two sections. Then, the Barker code was used for synchronization, the LWT (lifting wavelet transform) was performed on each section, a synchronization code and a watermark were embedded into the first section and the second section, respectively, by modifying the statistical average value of the sub-band coefficients. The embed strength was determined adaptively according to the auditory masking property. Experiments show that the embedded watermark has better robustness against common signal processing attacks than present algorithms based on LWT and can resist random cropping in particular.
Źródło:
Archives of Acoustics; 2010, 35, 4; 481-491
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of finite element meshing accuracy on a welding machine for offshore platform’s modal analysis
Autorzy:
Xie, J.
Sun, D.
Xu, C.
Wu, J.
Powiązania:
https://bibliotekanauki.pl/articles/260126.pdf
Data publikacji:
2018
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
finite element analysis
meshing
meshing accuracy
modal analysis
Opis:
The purpose objective of this study was to investigate the influence of finite element meshing accuracy on modal analysis which is one of the basic factors affecting the accuracy of finite element analysis and mostly preoccupies the working staff in pre-processing finite element simulation models. In this paper, we established several finite element models of a welding machine for offshore platform, with the meshing accuracy as the variable and workbench software as the platform for modal analysis, as the same time, comparing the analysis results. The results indicated that for some specific structures and simulation types, mesh refinement alone does not achieve desired results, and the authors indicate that mesh refinement is rarely related to the equipment’s low-frequency modal analysis but it’s great related to the equipment’s high-frequency modal analysis. The findings of this study may serve as breaking the opinion that smaller mesh size means higher calculation precision and provides references for mesh division practices in low frequency modal analysis.
Źródło:
Polish Maritime Research; 2018, S 3; 147-153
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Detonation Reaction Characteristics for CL-20 and CL-20-based Aluminized Mixed Explosives
Autorzy:
Liu, D.
Chen, L.
Wang, C.
Wu, J.
Powiązania:
https://bibliotekanauki.pl/articles/358308.pdf
Data publikacji:
2017
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
detonation reaction zone
aluminum reaction
interfacial particle velocity
interferometry
Opis:
The interfacial particle velocities for CL-20 and CL-20-based aluminized mixed explosives were measured by interferometry in order to analyze the aluminum reactions in the latter. The reaction characteristics were obtained, as well as a better understanding of the effects of aluminum powder on the detonation reaction zone length. Two functions were used to fit the particle velocity-time profiles, and their intersection was the corresponding Chapman-Jouget (CJ) point. From these profiles, the detonation reaction zone length and the aluminum reaction were then analyzed. CL-20-based explosives have a short reaction time (48 ns for a high CL-20 content), while the reaction time of CL-20/Al explosives increased with the aluminum content and particle size. Micron-scale aluminum particles barely reacted in the CL-20 detonation reaction zone, but instead reacted with the detonation products after the CJ point. This reduced the detonation pressure; however, the aluminum reaction can slow down the decrease in particle velocities. The start times of small-particle aluminum reactions were earlier than those of the larger particles. The 2-3-μm aluminum particles start to react within 1 μs after the CJ point, while the 200-nm particles may start to react in the reaction zone.
Źródło:
Central European Journal of Energetic Materials; 2017, 14, 3; 573-588
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A fault diagnosis method for substation grounding grid based on the square-wave frequency domain model
Autorzy:
Zhang, P.-H.
He, J.-J.
Zhang, D.-D.
Wu, L.-M.
Powiązania:
https://bibliotekanauki.pl/articles/221635.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
square-wave
frequency characteristics
grounding grid
fault diagnosis
Opis:
Current methods of fault diagnosis for the grounding grid using DC or AC are limited in accuracy and cannot be used to identify the locations of the faults. In this study, a new method of fault diagnosis for substation grounding grids is proposed using a square-wave. A frequency model of the grounding system is constructed by analyzing the frequency characteristics of the soil and the grounding conductors into which two different frequency square-wave sources are injected. By analyzing and comparing the corresponding information of the surface potentials of the output signals, the faults of the grounding grid can be diagnosed and located. Our method is verified by software simulation, scale model experiments and field experiments.
Źródło:
Metrology and Measurement Systems; 2012, 19, 1; 63-71
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simultaneous state and parameter estimation based actuator fault detection and diagnosis for an unmanned helicopter
Autorzy:
Wu, C.
Qi, J.
Song, D.
Qi, X.
Han, J.
Powiązania:
https://bibliotekanauki.pl/articles/329847.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
actuator fault detection
actuator fault diagnosis
unmanned helicopter
Kalman filter
set membership filter
adaptive scheme
detekcja uszkodzeń
diagnostyka uszkodzeń
śmigłowiec bezzałogowy
filtr Kalmana
Opis:
Simultaneous state and parameter estimation based actuator fault detection and diagnosis (FDD) for single-rotor unmanned helicopters (UHs) is investigated in this paper. A literature review of actuator FDD for UHs is given firstly. Based on actuator healthy coefficients (AHCs), which are introduced to represent actuator faults, a combined dynamic model is established with the augmented state containing both the flight state and AHCs. Then the actuator fault detection and diagnosis problem is transformed into a general nonlinear estimation one: given control inputs and the measured flight state contaminated by measurement noises, estimate both the flight state and AHCs recursively in each time-step, which is also known as the simultaneous state and parameter estimation problem. The estimated AHCs can further be used for fault tolerant control (FTC). Based on the existing widely used nonlinear estimation methods such as the unscented Kalman filter (UKF) and the extended set-membership filter (ESMF), three kinds of adaptive schemes (KF-UKF, MIT-UKF and MIT-ESMF) are proposed by our team to improve the actuator FDD performance. A comprehensive comparative study on these different estimation methods is given in detail to illustrate their advantages and disadvantages when applied to unmanned helicopter actuator FDD.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2015, 25, 1; 175-187
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Adsorption kinetics of fluoride on bone char and its regeneration
Autorzy:
Hu, J.
Wu, D.
Rao, R.
Liu, R.
Lai, W.
Powiązania:
https://bibliotekanauki.pl/articles/206892.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
chlorine compounds
fluorine compounds
ions
sodium compounds
sulfur compounds
adsorption kinetics
chemical reaction equilibrium
correlation coefficient
Freundlich equation
optimal conditions
layered double hydroxides
aqueous-solution
drinking water
equilibrium
adsorbent
związki chloru
związki fluoru
jod
związki sodu
związki siarki
kinetyka adsorpcji
równowaga reakcji chemicznej
współczynnik korelacji
równanie Freundlicha
woda pitna
równanie Langmuira
Opis:
The adsorbent of bone char (BC), produced from the pyrolysis of crushed animal bones, was dominated by the mesopores of the Brunauer Emmett Teller (BET) surface area. The optimal condition for defluoridation with BC was a pH level near 5.0. Chloride and nitrate ions could increase fluoride adsorption capacity in contrast with the effect of sulfate and carbonate ions. The interchangeability between fluoride and hydroxyl groups on BC sorbent was proved by the Fourier transform infrared spectroscopy. Langmuir equation had a better correlation coefficient than the Freundlich equation at various temperatures. Thermodynamic parameters such as Delta G degrees, Delta H degrees, Delta S degrees, Ea and S*, have been calculated to describe the nature of fluoride adsorption onto BC. Negative Delta G degrees and Delta H degrees values at various temperatures indicate a spontaneous process, and its exothermic effect, respectively. However, a positive Delta S degrees value represents an increasing process for entropy. The E-a and S* values ranging from 5 to 40 kj.mol-1 and 0 to 1, respectively, demonstrated that the adsorption is dominated by physical process, although the adsorption kinetic process was involved external diffusion, intraparticle diffusion and chemical reaction equilibrium stage. A high concentration of NaOH solution increases efficiency of removing adsorbed F- ions from the BC surface.
Źródło:
Environment Protection Engineering; 2017, 43, 3; 93-112
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Speech Enhancement Based on the Multi-Scales and Multi-Thresholds of the Auditory Perception Wavelet Transform
Autorzy:
Tao, Z.
Zhao, H. M.
Zhang, X-J.
Wu, D.
Powiązania:
https://bibliotekanauki.pl/articles/177021.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
speech enhancement
low SNR
auditory perception wavelet transform
unvoiced enhancement
masking effect
Opis:
This paper proposes a speech enhancement method using the multi-scales and multi-thresholds of the auditory perception wavelet transform, which is suitable for a low SNR (signal to noise ratio) environment. This method achieves the goal of noise reduction according to the threshold processing of the human ear’s auditory masking effect on the auditory perception wavelet transform parameters of a speech signal. At the same time, in order to prevent high frequency loss during the process of noise suppression, we first make a voicing decision based on the speech signals. Afterwards, we process the unvoiced sound segment and the voiced sound segment according to the different thresholds and different judgments. Lastly, we perform objective and subjective tests on the enhanced speech. The results show that, compared to other spectral subtractions, our method keeps the components of unvoiced sound intact, while it suppresses the residual noise and the background noise. Thus, the enhanced speech has better clarity and intelligibility.
Źródło:
Archives of Acoustics; 2011, 36, 3; 519-532
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-Coercivity FePt Nanoparticle Assemblies Embedded in Oxide-Matrix by Atomic Layer Deposition
Autorzy:
Kong, J.
Li, A.
Gao, M.
Yan, Q.
Wu, D.
Powiązania:
https://bibliotekanauki.pl/articles/1399662.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Vv
75.75.Cd
75.50.Bb
75.50.Ss
Opis:
Self-assembled face-centered cubic FePt nanoparticles were embedded into the oxide capping layer using the atomic layer deposition technology. The effect of the oxide-matrix layer on the structure, mono-dispersibility, and magnetic properties of the FePt/oxide composite thin films was investigated. Experimental results suggest that the protection of the oxide-matrix capping layer can effectively inhibit the grain growth and particle aggregation, and preserve the ordered domains of the FePt nanoparticles during the L 1_0 ordering transition through annealing. The combination of the atomic layer deposition capping layer and self-assembled FePt nanoparticles provides a new potential approach to fabricate the ultrahigh-density magnetic recording media.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 173-176
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Estimation of small uav position and attitude with reliable in-flight initial alignment for MEMS inertial sensors
Autorzy:
Wang, D.
Dong, Y.
Li, Q.
Wu, J.
Wen, Y.
Powiązania:
https://bibliotekanauki.pl/articles/221716.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
MEMS
INS
GNSS
in-flight alignment
unmanned aerial vehicle
Opis:
The advance of MEMS-based inertial sensors successfully expands their applications to small unmanned aerial vehicles (UAV), thus resulting in the challenge of reliable and accurate in-flight alignment for air-borne MEMS-based inertial navigation system (INS). In order to strengthen the rapid response capability for UAVs, this paper proposes a robust in-flight alignment scheme for airborne MEMS-INS aided by global navigation satellite system (GNSS). Aggravated by noisy MEMS sensors and complicated flight dynamics, a rotation-vector-based attitude determination method is devised to tackle the in-flight coarse alignment problem, and the technique of innovation-based robust Kalman filtering is used to handle the adverse impacts of measurement outliers in GNSS solutions. The results of flight test have indicated that the proposed alignment approach can accomplish accurate and reliable in-flight alignment in cases of measurement outliers, which has a significant performance improvement compared with its traditional counterparts.
Źródło:
Metrology and Measurement Systems; 2018, 25, 3; 603-616
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Emergency management of maritime accidents in the yangtze river: problems, practice and prospects
Autorzy:
Yan, X.P.
Wu, B.
Zhang, D.
Zhang, J. F.
Powiązania:
https://bibliotekanauki.pl/articles/117335.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
inland navigation
emergency management
Yangtze River
maritime accidents
artificial societies
Computational Experiments and Parallel Execution (ACP)
eastern star
inland shipping
oil spill
Opis:
Maritime accidents have received considerable attentions due to the enormous property damage, casualties and serious environmental pollution. This paper first makes statistical analysis of the different types of maritime accidents in the period of 2012 to 2014 in the Yangtze River. Second, the problems of emergency management of maritime accidents are also proposed from the analysis of the major accident “Eastern Star”.. Afterwards, four practice cases, including decision support for maritime accidents, emergency resource allocation, emergency simulation system and effectiveness of emergency management, are introduced to present the insights gained from these practices. Last, in order to address these problems, this paper proposes that an artificial societies, Computational experiments, and Parallel execution (ACP) approach should be introduced to establish an improved management system for maritime accidents in the future, and an ACP based maritime accident emergency management framework is proposed.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2017, 11, 1; 111-118
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Flotation behaviour and surface characteristic of anosovite in a sodium oleate solution
Autorzy:
Wang, Y.
Wen, S.
Zhang, J.
Wu, D.
Xian, Y.
Shen, H.
Powiązania:
https://bibliotekanauki.pl/articles/110766.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
anosovite
sodium oleate
flotation
adsorption
Opis:
Properties of anosovite in titanium slag, anosovite flotation response in a collector solution of sodium oleate, and adsorption behaviour of sodium oleate on the mineral surface were studied in the present work using XRD, Raman spectra, flotation tests, zeta potential analysis, FTIR and XPS. The results show that the anosovite crystal contains magnesium, and its chemical composition is Mg0.09Ti2.91O5. The chemical bonds on the anosovite surface mainly comprise Ti-O bonds. Micro-flotation tests indicate that anosovite has better floatability at a wide pH range and the recovery reaches 88% at pH=6, when the dosage of sodium oleate is only 4·10−6 mol/dm3. The point of zero charge of anosovite was determined near pH 3.2 by the zeta potential measurement. In the flotation process, chemical adsorption occurs between the carboxyl of sodium oleate and the titanium sites on the anosovite surface.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 2; 714-723
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Using chemometrics to identify water quality in Daya Bay, China
Autorzy:
Wu, M.-L.
Wang, Y.-S.
Sun, C.-C.
Wang, H.
Lou, Z.-P.
Dong, J.-D.
Powiązania:
https://bibliotekanauki.pl/articles/49096.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
robust principal component analysis
water quality
chemometrics
China
cluster analysis
Daya Bay
Opis:
In this paper, chemometric approaches based on cluster analysis, classical and robust principal component analysis were employed to identify water quality in Daya Bay (DYB), China. The results show that these approaches divided water quality in DYB into two groups: stations S3, S8, S10 and S11 belong to cluster A, which lie in Dapeng Cove, Aotou Harbor and the north-eastern part of DYB, where water quality is related mainly to anthropogenic activities. The other stations belong to cluster B, which lie in the southern, central and eastern parts of DYB, where the quality is related mainly to water exchange with the South China Sea. Cluster analysis yields good results as a first exploratory method for evaluating spatial difference, but it fails to demonstrate the relationship between variables and environmental quality on the one hand and the untreated data on the other. However, with the aid of suitable chemometric approaches, the relationship between samples or variables can be investigated. Classical and robust principal component analysis can provide a visual aid for identifying the water environment in DYB, and then extracting specific information about relationships between variables and spatial variation trends in water quality.
Źródło:
Oceanologia; 2009, 51, 2; 217-232
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The unsteadiness of tip clearance flow and its effect to stability of transonic axial compressor
Nieustaloność przepływu w szczelinie wierzchołkowej i jej wpływ na stabilność pracy przydźwiękowej sprężarki osiowej
Autorzy:
Hu, J. F.
Zhu, X. C.
Ou-Yang, H.
Tian, J.
Wu, Y. D.
Qiang, X. Q.
Zhao, G.
Du, Z. H.
Powiązania:
https://bibliotekanauki.pl/articles/281445.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
tip leakage flow
compressor
stability
Opis:
The steady and unsteady RANS simulations of a transonic compressor rotor (NASA rotor 37) are performed to investigate the tip clearance flow characteristic and correlations between tip leakage flow and compressor stability. For steady simulations, the results are compared with the aerodynamic probe and laser anemometer data. The speed lines and span-wise aerodynamic parameters agree well with the experimental data. On the other hand, the tip clearance flow of unsteady simulations are analysed clearly at a near stall condition. The results show that there is a mass flow rate boundary. The tip clearance flow oscillates substantially with a frequency about 50% BPF when the mass is less than that, which is caused by tip clearance flow, shock, and the interaction between them and the oncoming flow. The interface between the oncoming flow and clearance flow shifts forward, and the tip clearance flow may spill over into the adjacent blade passage as the mass flow decreases, which may results in the spike stall inception.
W pracy przedstawiono symulacje stanu ustalonego i nieustalonego przydźwiękowej sprężarki osiowej (turbina NASA 37) z zastosowaniem metody Reynoldsa uśredniania równań Naviera-Stokesa (RANS) w celu zbadania charakterystyki przepływu w szczelinie wierzchołkowej oraz określenia zależności pomiędzy stratami związanymi z upływem w tej szczelinie a stabilnością pracy sprężarki. Wyniki symulacji stanu ustalonego porównano z danymi doświadczalnymi uzyskanymi za pomocą sondy aerodynamicznej i laserowego wiatromierza. Wyznaczone wzdłuż rozpiętości sprężarki linie prędkości przepływu i jego parametry aerodynamiczne okazały się zgodne z danymi doświadczalnymi. W przypadku symulacji stanu nieustalonego, analizę przepływu w szczelinie wierzchołkowej przeprowadzono dla warunków bliskich oderwania, tj. utraty wydajności sprężarki, wyznaczając graniczny wydatek przepływu dla takiej sytuacji. Poniżej tej granicznej wartości, zmiany przepływu w szczelinie oscylują z częstotliwością sięgającą 50% częstotliwości przejścia łopatek (tzw. BPF), co jest konsekwencją interakcji wywołanej zderzeniem przepływu z falą napływową w szczelinie wierzchołkowej. Powierzchnia tej interakcji przesuwa się do przodu, a sam przepływ może rozpaść się na fragmenty znajdujące ujście w kanałach przyległych łopatek. Zjawisko to zachodzi przy malejącym wydatku, a to z kolei może indukować oderwanie przepływu skokowymi zmianami mocy współpracującego silnika.
Źródło:
Journal of Theoretical and Applied Mechanics; 2013, 51, 2; 431-438
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
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