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Tytuł:
2D numerical analysis of an H-Darrieus hydrokinetic turbine with passive improvement mechanisms
Autorzy:
Guevara-Munoz, Angie Judith
Hincapie-Zuluaga, Diego Andres
Rodriguez-Cabal, Miguel Angel
Sierra-Del-Rio, Jorge Andres
Colmenares-Quintero, Ramón Fernando
Torres-Lopez, Edwar
Powiązania:
https://bibliotekanauki.pl/articles/38911523.pdf
Data publikacji:
2023
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
renewable energy
H-Darrieus rotor
hydrokinetics
diffusers
computational fluid dynamic
CFD
external accessories
Opis:
H-Darrieus hydrokinetic turbines are an alternative for small hydroelectric plants. These turbines are considered to have a low environmental impact as they do not require reservoirs. However, they have limited self-starting capacity, which limits their use. Nevertheless, the configuration of passive mechanisms in the H-Darrieus turbines affects their performance, as they tend to increase the flow velocity. This study is part of a project with the aim to design and build a turbine to generate energy in the Colombian river scenario in non-interconnected zones. The objective of this study is to analyze the performance through numerical simulations of four H-Darrieus rotors to be configured with passive improvement mechanisms. The study was conducted using ANSYS® Fluent software, employing transient, two-dimensional models under constant operating conditions. Overlapping meshes were used for the stationary and rotating domain configuration. The results show that increased solidity leads to decreased tip speed ranges and increased maximum rotor power. Improvement in the self-starting capability was found with passive mechanisms employing a diffuser geometry. Among the tested configurations, the rotor configured with a Venturi-shaped mechanism achieved a remarkable 660% improvement in the power coefficient compared to configurations without such mechanisms.
Źródło:
Engineering Transactions; 2023, 71, 4; 553-569
0867-888X
Pojawia się w:
Engineering Transactions
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A low emission coastal cruise vessel – MV havila capella
Autorzy:
Berg, T.E.
Moe, S.E.
Leinebø, D.
Rabliås, Ø
Powiązania:
https://bibliotekanauki.pl/articles/24201391.pdf
Data publikacji:
2023
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
analogical manoeuvring simulator
in-situ model test
sea trial test
low emission
passenger vessels
batteries
CFD method
wind model
Opis:
Since January 2021, Havila Kystruten has been one of two companies sailing the coastal route between Bergen and Kirkenes. This paper contains information on the new shipping company Havila Kystruten and their 2019 bid for a 10-year operational license to sail the coastal route. The government's tender documents for the new license specified that the vessels operating the route had to be low-emission vessels. This requirement was in line with the government's white paper on the reduction of emissions for commercial and fishing vessels sailing in Norwegian waters. Thus, companies bidding for the new license had to offer new ships with low emission characteristics or rebuild existing vessels to obtain the low emission requirements. Based on the offers, the government decided to split the operational license between two companies. One part was given to the company previously operating the route (Hurtigruten) and the other to the new company Havila Kystruten. While Hurtigruten would rebuild the engine systems on some of their existing vessels, Havila Kystruten would operate the route using new vessels with low emission signature. The design requirements for these vessels were given by Havila Kystruten to the ship designer, Havyard Design and Solutions (now HAVDesign). Some of the requirements are listed in section 4 below. The latter part of this paper investigates the manoeuvring performance of the new Havila Kystruten vessels, containing a summary of a Research Council of Norway funded innovation project on harsh weather ship handling during port operations. The Port of Trondheim was selected as a case study.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2023, 17, 1; 165--170
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Aerodynamic investigation on the artefact “bird of Saqqara”
Autorzy:
Zierow, Michel
Lesemann, Leon
Powiązania:
https://bibliotekanauki.pl/articles/2233069.pdf
Data publikacji:
2023
Wydawca:
Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
Tematy:
Saqqara
bird
aerodynamics
archaeology
CFD
flight mechanics
Paleo-SETI
Egypt
Ancient Aliens
Opis:
Lost, technical knowledge of ancient cultures is being rediscovered in modern times during archaeological excavations. A presumed example of the innovative power of ancient cultures is the artefact “Bird of Saqqara”. In the context of this paper, the aerodynamic characteristics of the artefact are to be determined by a computational fluid simulation, in order to be able to make a statement about the actual flight suitability and to examine the theses of the pre-astronautics critically. Based on a 3D scan, a CAD model of the artefact is created and then a numerical flow simulation is performed. By varying the angle of attack, the dimensionless coefficients can be represented in corresponding polars. The results show that the artefact has a low maximum glide ratio and thus the glide properties are not sufficient for use as a handglider. The centre of gravity of the artefact is located at the trailing edge of the wing and behind the neutral point. The resulting longitudinal stability does not meet modern specifications. Asymmetric lift distribution in the spanwise direction results in uncontrolled roll. Consequently, the artefact cannot fly a straight path. Within the scope of this work, the connection between the “Bird of Saqqara” and an alleged knowledge of aerodynamics in ancient Egypt could not be confirmed.
Źródło:
Acta Mechanica et Automatica; 2023, 17, 3; 405--409
1898-4088
2300-5319
Pojawia się w:
Acta Mechanica et Automatica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Airfoil Tonal Noise Prediction Using Urans
Autorzy:
Klimczyk, Witold
Sieradzki, Adam
Powiązania:
https://bibliotekanauki.pl/articles/36829323.pdf
Data publikacji:
2023
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
Tematy:
airfoil tonal noise
aeroacoustics
CFD
Opis:
To examine the feasibility of the laminar boundary layer (LBL), vortex shedding (VS) tonal noise modelling using unsteady Reynolds-averaged Navier-Stokes (URANS) was investigated for the non-symmetric S834 airfoil. A transition SST turbulence model was used to model the laminar-turbulent transition and its vital influence on the laminar bubble and hydrodynamic instabilities generation. The influence of turbulence on the unsteady vortex patterns was investigated. Hence, the hybrid aeroacoustic analysis with Lighthill analogy was conducted to obtain the acoustic pressure field. The approach allowed us to model hydrodynamic instabilities and the resulting VS tonal noise. The frequency of VS matched the experimental data, giving the same 1/3 octave tonal peak only for a limited freestream turbulence regime. The simplification of the present method did not allow us to model the aeroacoustic feedback loop, and resulted in lack of instabilities for higher freestream turbulence.
Źródło:
Transactions on Aerospace Research; 2023, 4 (273); 1-17
0509-6669
2545-2835
Pojawia się w:
Transactions on Aerospace Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of heat and mass transfer in an adsorption bed using CFD methods
Autorzy:
Janusz, Szymon
Szudarek, Maciej
Rudniak, Leszek
Borcuch, Marcin
Powiązania:
https://bibliotekanauki.pl/articles/27312232.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
heat transfer
adsorption
CFD
mass transfer
refrigeration devices
Opis:
The trend of reducing electricity consumption and environmental protection has contributed to the development of refrigeration technologies based on the thermal effect of adsorption. This article proposes a methodology for conducting numerical simulations of the adsorption and desorption processes. Experimental data available in the literature were used as guidelines for building and verifying the model, and the calculations were carried out using commercial computational fluid dynamics software. The simulation results determined the amount of water vapor absorbed by the adsorbent bed and the heat generated during the adsorption process. Throughout the adsorption process, the inlet water vapor velocity, temperature, and pressure in the adsorbent bed were monitored and recorded. The results obtained were consistent with the theory in the literature and will serve as the basis for further, independent experimental studies. The validated model allowed for the analysis of the effect of cooling water temperature on the sorption capacity of the material and the effect of heating water temperature on bed regeneration. The proposed approach can be useful in analyzing adsorption processes in refrigeration applications and designing heat and mass exchangers used in adsorption systems.
Źródło:
Archives of Thermodynamics; 2023, 44, 2; 177--194
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
CFD-DEM simulation of raceway size and mechanical characteristics of industrial scale blast furnace
Autorzy:
Gao, Yuzhen
Chan, Choon Kit
Powiązania:
https://bibliotekanauki.pl/articles/27315659.pdf
Data publikacji:
2023
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
raceway
CFD-DEM
Computional Fluid Dynamics
Discrete Element Method
numerical simulation
blast furnace
Opis:
The raceway plays a crucial role in ensuring the stable functioning of the ironmaking blast furnace. It is the key site where the chemical reaction of coke combustion takes place, providing the necessary heat and reducing gas for the upper iron ore reduction process. Consequently, the size of the raceway serves as an essential indicator of the blast furnace’s operational condition. In this study, a mathematical model for the raceway of an industrial-scale blast furnace was established. Extensive innovation investigations were conducted to explore the characteristics pertaining to the raceway’s size. The simulation outcomes demonstrate that both the particle size and the inlet velocity exert significant influences on the raceway dimensions. Specifically, the height of the raceway is predominantly affected by the particle size, whereas the inlet velocity predominantly influences the depth of the raceway.
Źródło:
Polish Journal of Chemical Technology; 2023, 25, 3; 71--78
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Computational evaluation of assembly technique influence on ballistic performance of a bullet – non-linear relation between méplat size and the drag coefficient
Analiza numeryczna wpływu metody montażu elementów pocisku na charakterystyki balistyczne – nieliniowa zależność współczynnika oporu od średnicy wierzchołka
Autorzy:
Piasta, Krzysztof
Kupidura, Przemysław
Michalski, Jakub
Powiązania:
https://bibliotekanauki.pl/articles/31232977.pdf
Data publikacji:
2023
Wydawca:
Politechnika Rzeszowska im. Ignacego Łukasiewicza. Oficyna Wydawnicza
Tematy:
mechanical engineering
ballistics
assembly methods
CFD
ammunition
inżynieria mechaniczna
balistyka
metody montażu
amunicja
Opis:
The continuous development of production and assembly techniques gives rise to the idea of following a new approach in the small-arms ammunition design process. Commonly used intermediate cartridges were designed over 60 years ago, and their construction and assembly processes are not significantly different than what was available almost a century ago. Along with the recent development of individual protection devices and with the general availability of modern ballistic plates utilized in plate carriers type of individual armor, it sparks the necessity of designing a new, intermediate cartridge, using new assembly and technology methods. The vital aspect of the ammunition design process is a determination of the materials utilized in bullet elements and its assembly method. Therefore, there is a necessity of evaluating if different assembly techniques can provide the improved ballistic performance of a bullet. The paper includes a comparison of two differently assembled projectiles with steel penetrators: a standard Full Metal Jacket and a reverse-drawn Semi-Jacketed bullet. The designs were evaluated in terms of their external ballistic performance for specific initial conditions using 2D Computational Fluid Dynamics simulations and, separately, with a semi-empirical method. The paper aimed to assess the influence of the assembly method on the bullet’s external ballistic performance. Both calculations revealed a nonlinear relation between the projectile méplat diameter and the coefficient of drag, which indicates a limit where the méplat size reduction is beneficial. The results implicate a perspective bullet construction that would provide the user with better external ballistic performance, more consistent and precise than a standard Full Metal Jacket design.
Nieustanny rozwój technik produkcji i montażu rodzi pomysł wykorzystania nowego podejścia w procesie projektowania amunicji do broni strzeleckiej. Obecnie powszechnie stosowane naboje pośrednie zostały zaprojektowane ponad 60 lat temu, a proces ich wykonania i montażu nie różni się znacząco od technologii dostępnej na początku XX wieku. Biorąc pod uwagę dynamiczny rozwój środków ochrony indywidualnej w ostatnim czasie oraz powszechną dostępność nowoczesnych płyt balistycznych stosowanych w kamizelkach kuloodpornych typu plate carrier, zaistniała potrzeba zaprojektowania nowego naboju pośredniego, stosując nowoczesne technologie i metody montażu. Jednym z najistotniejszych aspektów procesu projektowania amunicji jest określenie materiału elementów pocisku oraz sposobu ich montażu, dlatego zasadne jest określenie wpływu metody montażu elementów pocisku na jego właściwości balistyczne. Artykuł zawiera porównanie dwóch różniących się metodą montażu pocisków z rdzeniem stalowym: standardowego pocisku pełnopłaszczowego oraz pocisku półpłaszczowego. Konstrukcje zostały ocenione pod kątem ich charakterystyk balistyki zewnętrznej dla określonych warunków początkowych za pomocą symulacji komputerowej dynamiki płynów w 2D oraz niezależnie wykorzystując program balistyczny. Celem pracy była ocena wpływu sposobu montażu elementów na właściwości balistyczne pocisku. Obie metody obliczeniowe wykazały nieliniową zależność między wielkością średnicy wierzchołka pocisku a współczynnikiem oporu, wskazując zakres wartości, do których zmniejszanie rozmiaru wierzchołka jest uzasadnione. Wyniki wskazują perspektywiczną konstrukcję pocisku, która zapewniłaby użytkownikowi lepsze charakterystyki balistyki zewnętrznej, zapewniając lepszą powtarzalność i precyzję niż standardowa konstrukcja pocisku pełnopłaszczowego.
Źródło:
Technologia i Automatyzacja Montażu; 2023, 2; 11-18
2450-8217
Pojawia się w:
Technologia i Automatyzacja Montażu
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Deposition effect of carbon deposits on charge flow in EGR valve equipped CI engine
Autorzy:
Woźniak, Marek
Siczek, Krzysztof
Zakrzewski, Sergiusz
Just, Paweł
Ozuna, Gustavo
Onescu, Constantin
Powiązania:
https://bibliotekanauki.pl/articles/24202415.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Naukowe Silników Spalinowych
Tematy:
CI engine
EGR valve
carbon deposits
CFD analysis
silnik ZS
zawór EGR
depozyty węglowe
analiza CFD
Opis:
The exhaust gas recirculation (EGR) valve regulates the exhaust gas flow between the engine exhaust manifold and the inlet one. This allows the inlet air to warm up, improving fuel evaporation and reducing the combustion temperature of the charge. Such a valve reduces the number of harmful substances in the exhaust gases. The valve tends to stick when too much sediment builds on the walls of the exhaust system, especially during driving in urban conditions or when leaks in the vacuum or exhaust pipes occur. A faulty valve causes the engine to run unevenly at idle speed and under light loads. The defective EGR valve weakens the inlet manifold capacity, increases combustion, causes clogging of the particulate filter and damage to the lambda probe. Blocked EGR valve may lead to engine immobilization as a result of its computerized control system operations. A model of an EGR valve for a selected diesel engine was developed to determine velocity distribution of the load flowing in it for different values of the degree of valve opening and the volume of deposits on the valve walls. The volume of accumulated carbon deposits on the walls of the EGR valve was measured using a real engine. Based on the recorded mileage of the vehicle, the assumed average speed of the car and the driving style of the driver and the intensity of deposition of carbon particles on the walls was estimated.
Źródło:
Combustion Engines; 2023, 62, 1; 26--35
2300-9896
2658-1442
Pojawia się w:
Combustion Engines
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of D-shaped, reverse D-shaped and U-shaped turbulators in solar air heater on thermo-hydraulic performance
Autorzy:
Ghildyal, Abhishek
Bisht, Vijay Singh
Bhandari, Prabhakar
Rawat, Kamal Singh
Powiązania:
https://bibliotekanauki.pl/articles/27312225.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
CFD
renewable energy
solar air heater
turbulence kinetic energy
thermo-hydraulic performance
Opis:
As the cost of fuel rises, designing efficient solar air heaters (SAH) becomes increasingly important. By artificially roughening the absorber plate, solar air heaters’ performance can be augmented. Turbulators in different forms like ribs, delta winglets, vortex generators, etc. have been introduced to create local wall turbulence or for vortex generation. In the present work, a numerical investigation on a solar air heater has been conducted to examine the effect of three distinct turbulators (namely D-shaped, reverse D- and U-shaped) on the SAH thermo-hydraulic performance. The simulation has been carried out using the computational fluid dynamics, an advanced and modern simulation technique for Reynolds numbers ranging from 4000 to 18000 (turbulent airflow). For the purpose of comparison, constant ratios of turbulator height/hydraulic diameter and pitch/turbulator height, of 0.021 and 14.28, respectively, were adopted for all SAH configurations. Furthermore, the fluid flow has also been analyzed using turbulence kinetic energy and velocity contours. It was observed that the U-shaped turbulator has the highest value of Nusselt number followed by D-shaped and reverse D-shaped turbulators. However, in terms of friction factor, the D-shaped configuration has the highest value followed by reverse D-shaped and U-shaped geometries. It can be concluded that among all SAH configurations considered, the U-shaped has outperformed in terms of thermohydraulic performance factor.
Źródło:
Archives of Thermodynamics; 2023, 44, 2; 3--20
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of propeller fouling on the hydrodynamic performance of a marine propeller
Autorzy:
Zinati, Ali
Ketabdari, Mohammad Javad
Zeraatgar, Hamid
Powiązania:
https://bibliotekanauki.pl/articles/34602878.pdf
Data publikacji:
2023
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
propeller performances
blade roughness
frictional resistance
CFD simulation
fouling
Opis:
Propeller performance is typically considered under clean conditions, despite the fact that fouling is an inevitable phenomenon for propellers. The main objective of this study is to investigate the effects of roughness due to fouling on the performance of a propeller using a CFD simulation in conjunction with the roughness function model. A simulation of a clean propeller is verified for a five-blade propeller model using existing experimental results. A roughness function model is then suggested based on existing measured roughness data. The simulations are extended for the same propeller under varying severities of roughness. Initially, it is concluded that KT and ηo gradually decrease with increasing fouling roughness, while KQ increases, compared to smooth propeller. For instance, at J=1.2 for medium calcareous fouling, KT is reduced by about 26%, KQ increases by about 7.0%, and ηo decreases by 30.9%. In addition, for the rough propeller, the extra power required is defined as the specific sea margin (SSM) to compensate for the power loss. A slight roughness causes a large decrease in ηo. A propeller painted with foul-release paint and an unpainted propeller are found to require 2.7% SSM and 57.8% SSM over four years of service, respectively. Finally, the use of foul-release paints for propeller painting is strongly advised.
Źródło:
Polish Maritime Research; 2023, 4; 61-73
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Elastohydrodynamic analysis of a journal bearing with different grade oils considering thermal and cavitation effects using CFD-FSI
Autorzy:
Kadhim, Zainab H.
Hammed, Lekaa
Rahima, Fatima A.
Ridha, Ali Mohammed
Powiązania:
https://bibliotekanauki.pl/articles/2203641.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Tematy:
journal bearing
hydrodynamic lubrication
thermal effect
elastic deformation
cavitation effect
CFD
smarowanie hydrodynamiczne
efekt cieplny
odkształcenie sprężyste
łożysko
Opis:
This paper investigates a three-dimensional CFD analysis of hydrodynamic journal bearing performance for two different available types of lubricants, SEA 10W50 and SEA 15W40, considering thermal, elastic deformation, and cavitation effects. A 3-dimensional CFD model founded on continuity, momentum, energy, in addition elasticity equations has been implemented. The analysis is performed for a bearing with different journal speeds (1000-3000rpm) and eccentricity ratios (0.1-0.9). The cavitation effect was considered using the model of Zwart-Gerber-Balamri multiphase flow model. The bearing material elastic deformation was considered by implementing the two-way FSI technique through ANSYS-FLUENT 2019 R2. A comparative study of the oil film temperature, thermal pressure, also the load capacity by the bearing has been performed. By comparing the current work's oil film temperature results with those obtained by Ferron et al (1983), with a maximum deviation between the results not exceeding 3 percent, the mathematical model was validated. The findings demonstrate that, once the cavitation consequence is taken into account, the lubricant film pressure decreases. Furthermore, at what time the bearing rotates at greater eccentricity ratios and rotational speeds, more deformation material of the bearing is seen. The current research may help in predicting the bearing performance parameters in real-world situations.
Źródło:
Diagnostyka; 2023, 24, 2; art. no. 2023213
1641-6414
2449-5220
Pojawia się w:
Diagnostyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental and numerical analyses of airflow around two cylinders angled to the direction of wind
Autorzy:
Padewska-Jurczak, Agnieszka
Szczepaniak, Piotr
Walentyński, Ryszard
Powiązania:
https://bibliotekanauki.pl/articles/2204499.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
wind action
CFD
computational fluid dynamics
FVM
finite volume method
ANSYS Fluent
wind tunnel test
water slide
działanie wiatru
obliczeniowa dynamika płynów
metoda objętości skończonych
testy w tunelu aerodynamicznym
zjeżdżalnia wodna
Opis:
The analyses aim to determine aerodynamic force coefficients in the case of airflow around two smooth or rough cylinders positioned at different angles to the direction of wind velocity. Such systems, for instance, may be part of a tubular water slide. The results were compared with the values of the interference coefficient of the cylinders arranged in a row included in Eurocode EN 1991 part 4. The aerodynamic forces of the cylinder systems were determined on the basis of experimental tests conducted in a wind tunnel. To verify the above results, CFD (computational fluid dynamics) simulations were prepared. An important observation is that for the angle of yaw β = 0◦, the negative component of the lift force (lateral) fy is shown, while for the other cases, the situation is opposite and the lateral force points outside the gap (upward). The second is that the results of aerodynamic drag for rough cylinders arranged in a row and calculated according to EN 1991 part 4 may be underestimated. The flow around the pair of smooth cylinders is quite different from that of the rough ones, because during the experiment the first falls into the critical flow regime, while the second has supercritical characteristics.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2023, 71, 1; art. no. e144578
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High quality multi-zone and 3d CFD model of combustion in marine diesel engine cylinder
Autorzy:
Cuper-Przybylska, Dominika
Nguyen, Van Nhanh
Cao, Dao Nam
Kowalski, Jerzy
Powiązania:
https://bibliotekanauki.pl/articles/32921247.pdf
Data publikacji:
2023
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
CFD combustion model
large 4-stroke engine
diesel engine
emission
NOx concentration
Opis:
The paper presents a 3D model of the processes taking place in the cylinder of a large 4-stroke marine engine. The model is based on CFD calculations performed on the moving mesh. The modelling range includes the full duty cycle (720° crankshaft position) and the complete geometry of the cylinder with inlet and exhaust ducts. The input data, boundary conditions and validation data were obtained by direct measurements on the real object. Fuel injection characteristics were obtained by Mie scattering measurements in a fixed-volume chamber. The modelling results have been validated in terms of the pressure characteristics of the engine’s cylinder within the entire range of its loads. The mean error did not exceed 1.42% for the maximum combustion pressure and 1.13% for the MIP (Mean Indicated Pressure). The model was also positively validated in terms of the O2 and NOx content of the exhaust gas. The mean error in this case was 1.2% for NOx fractions in the exhaust gas and 0.4% for O2 fractions. The complete model data has been made available in the research data repository on an open access basis.
Źródło:
Polish Maritime Research; 2023, 2; 61-67
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of impeller blade rounding and surface roughness on the internal hydraulics and performance of pump as turbine
Autorzy:
Gaji, Rahul
Doshi, Ashish
Bade, Mukund
Singh, Punit
Powiązania:
https://bibliotekanauki.pl/articles/27309885.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
pump as turbine
impeller blade rounding
CFD analysis of PAT
simple modifications in PAT
hydraulic analysis
pompa jako turbina
zaokrąglenie łopatek wirnika
Analiza CFD PAT
proste modyfikacje w PAT
analiza hydrauliczna
Opis:
The Pump As Turbine (PAT) is an important technology for low-cost micro-hydropower and energy recovery, and hence the internal hydraulics of PAT needs to be clearly understood. Additionally, during its operation, the sediments in the water increase the roughness of the internal surfaces and may alter the internal hydraulics and PAT performance similar to a centrifugal pump or Francis turbine. The researchers tried hard to perform simple modifications such as impeller blade rounding to increase the efficiency of PAT. In this paper, the developed test rig is used to analyze the performance of the impeller blade rounding and is validated with a numerical model. This numerical model is further used to study the influence of impeller blade rounding and surface roughness on internal hydraulics and PAT performance. The impeller blade rounding at the most increased the PAT efficiency by 1-1.5 % at the Best efficiency point (Q=16.8 lps), mainly due to the wake reduction on the suction side and increased flow area. With increasing the surface roughness from 0-70 μm, the PAT efficiency is decreased maximum by 4 %. The efficiency was mainly reduced due to increased hydraulic losses at flow zone and disk friction losses at the non-flow zone.
Źródło:
Archive of Mechanical Engineering; 2023, LXX, 2; 219--245
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of thermal-flow characteristics of the minichannel heat exchanger of variable louvers height
Autorzy:
Romaniak, Artur
Kowalczyk, Michał Jan
Łęcki, Marcin
Gutkowski, Artur
Górecki, Grzegorz
Powiązania:
https://bibliotekanauki.pl/articles/27312209.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
CFD
heat transfer
heat pump
louvered fin
minichannel heat exchanger
Opis:
The numerical simulation of the heat transfer in the flow channels of the minichannel heat exchanger was carried out. The applied model was validated on the experimental stand of an air heat pump. The influence of louver heights was investigated in the range from 0 mm (plain fin) to 7 mm (maximum height). The set of simulations was prepared in Ansys CFX. The research was carried out in a range of air inlet velocities from 1 to 5 m/s. The values of the Reynolds number achieved in the experimental tests ranged from 93 to 486. The dimensionless factors, the Colburn factor and friction factor, were calculated to evaluate heat transfer and pressure loss, respectively. The effectiveness of each louver height was evaluated using the parameter that relates to the heat transfer and the pressure drop in the airflow. The highest value of effectiveness (1.53) was achieved by the louver height of 7 mm for the Reynolds number of around 290.
Źródło:
Archives of Thermodynamics; 2023, 44, 3; 119--141
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 664

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