Energies

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20 pages, 7645 KiB

Open AccessArticle

Optimization of the Aircraft Air/Oil Separator by the Response Surface Determined from Modeling of Three-Dimensional Two-Phase Flow

by Tomasz Szwarc, Włodzimierz Wróblewski and Tomasz Borzęcki

Energies 2022, 15(19), 7273; https://doi.org/10.3390/en15197273 - 3 Oct 2022

Cited by 1 | Viewed by 1965

Abstract

This paper presents optimisation of the geometry of the aircraft air–oil separator (AAOS) performed to improve the device performance. For this separator type, the most important operating parameters are the oil quality, efficiency and pressure drop. In order to understand the relationships between [...] Read more.

This paper presents optimisation of the geometry of the aircraft air–oil separator (AAOS) performed to improve the device performance. For this separator type, the most important operating parameters are the oil quality, efficiency and pressure drop. In order to understand the relationships between geometric parameters and their impact on the parameters of the separator operation, an analysis was conducted using the Response Surface Method (RSM). The analysis was made based on the results of numerical simulations and using the volume-of-fluid (VOF) method. Pareto analysis was also carried out, which determined the impact of the inlet width and height and the separator diameter on the device performance. By solving the optimisation task using a genetic algorithm, it was possible to propose a new geometry for the AAOS. The favourable geometric relations for the AAOS are indicated and they are compared with those preferred for other geometries of cyclone separators. Full article

(This article belongs to the Special Issue Turbomachinery, Energy and Environmental Technologies)

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22 pages, 11130 KiB

Open AccessArticle

Preliminary Design and Blade Optimization of a Two-Stage Radial Outflow Turbine for a CO₂ Power Cycle

by Jun-Seong Kim, You-Taek Kim and Do-Yeop Kim

Energies 2022, 15(17), 6240; https://doi.org/10.3390/en15176240 - 26 Aug 2022

Cited by 2 | Viewed by 2322

Abstract

Recently, the CO₂ power cycle has attracted attention because of tightening environmental regulations. The turbine is a factor that greatly affects the efficiency of the cycle. The radial outflow turbine is a turbomachine with the various advantages of an axial flow turbine [...] Read more.

Recently, the CO₂ power cycle has attracted attention because of tightening environmental regulations. The turbine is a factor that greatly affects the efficiency of the cycle. The radial outflow turbine is a turbomachine with the various advantages of an axial flow turbine and a radial inflow turbine, but the design theory for the turbine is uncertain. In this study, a preliminary design algorithm for a radial outflow turbine with a multi-stage configuration is presented. To verify the preliminary design algorithm, a preliminary design for a two-stage radial outflow turbine for a CO₂ power cycle was carried out, and a computational fluid dynamic analysis was performed. Consequently, values close to the target performance were obtained, but blade optimization was performed to obtain more satisfactory results. The final geometry of the radial outflow turbine was obtained through optimization considering the blade exit angle related to the deviation angle, blade maximum thickness-true chord ratio, and incidence angle. In the final geometry, the error rates of power (

\dot{W}

), efficiency (

η_{t s}

), and pressure ratio (

P R_{t s}

) between target performance and computational fluid dynamic results were improved to 5.0%, 4.8%, and 1.8%, respectively. The performance and flow characteristics of the initial and final geometries were analyzed. Full article

(This article belongs to the Special Issue Turbomachinery, Energy and Environmental Technologies)

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28 pages, 15755 KiB

Open AccessArticle

Towards an Accurate Aerodynamic Performance Analysis Methodology of Cross-Flow Fans

by Rania M. Himeur, Sofiane Khelladi, Mohamed Abdessamed Ait Chikh, Hamid Reza Vanaei, Idir Belaidi and Farid Bakir

Energies 2022, 15(14), 5134; https://doi.org/10.3390/en15145134 - 14 Jul 2022

Cited by 8 | Viewed by 2889

Abstract

Cross-flow fans (CFFs) have become increasingly popular in recent years. This is due to their use in several domains such as air conditioning and aircraft propulsion. They also show their utility in the ventilation system of hybrid electric cars. Their high efficiency and [...] Read more.

Cross-flow fans (CFFs) have become increasingly popular in recent years. This is due to their use in several domains such as air conditioning and aircraft propulsion. They also show their utility in the ventilation system of hybrid electric cars. Their high efficiency and performance significantly rely on the design parameters. Up to now, there is no general approach that predicts the CFFs’ performance. This work describes a new methodology that helps deduce the performance of CFFs in turbomachinery, using both analytical modeling and experimental data. Two different loss models are detailed and compared to determine the performance–pressure curves of this type of fan. The efficiency evaluation is achieved by realizing a multidisciplinary study, computational fluid dynamics (CFD) simulations, and an optimization algorithm combined to explore the internal flow field and obtain additional information about the eccentric vortex, to finally obtain the ultimate formulation of the Eck/Laing CFF efficiency, which is validated by the experimental results with good agreement. This approach can be an efficient tool to speed up the cross-flow fans’ design cycle and to predict their global performance. Full article

(This article belongs to the Special Issue Turbomachinery, Energy and Environmental Technologies)

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16 pages, 4848 KiB

Open AccessArticle

Design and Optimization of a Radial Inflow Turbine for Use with a Low Temperature ORC

by Richard Symes, Tchable-Nan Djaname, Michael Deligant and Emilie Sauret

Energies 2021, 14(24), 8526; https://doi.org/10.3390/en14248526 - 17 Dec 2021

Cited by 3 | Viewed by 2150

Abstract

This study aims to design and optimize an organic Rankine cycle (ORC) and radial inflow turbine to recover waste heat from a polymer exchange membrane (PEM) fuel cell. ORCs can take advantage of low-quality waste heat sources. Developments in this area have seen [...] Read more.

This study aims to design and optimize an organic Rankine cycle (ORC) and radial inflow turbine to recover waste heat from a polymer exchange membrane (PEM) fuel cell. ORCs can take advantage of low-quality waste heat sources. Developments in this area have seen previously unusable, small waste heat sources become available for exploitation. Hydrogen PEM fuel cells operate at low temperatures (70 °C) and are in used in a range of applications, for example, as a balancing or backup power source in renewable hydrogen plants. The efficiency of an ORC is significantly affected by the source temperature and the efficiency of the expander. In this case, a radial inflow turbine was selected due to the high efficiency in ORCs with high density fluids. Small scale radial inflow turbines are of particular interest for improving the efficiency of small-scale low temperature cycles. Turbines generally have higher efficiency than positive displacement expanders, which are typically used. In this study, the turbine design from the mean-line analysis is also validated against the computational fluid dynamic (CFD) simulations conducted on the optimized machine. For the fuel cell investigated in this study, with a 5 kW electrical output, a potential additional 0.7 kW could be generated through the use of the ORC. The ORC’s output represents a possible 14% increase in performance over the fuel cell without waste heat recovery (WHR). Full article

(This article belongs to the Special Issue Turbomachinery, Energy and Environmental Technologies)

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17 pages, 11686 KiB

Open AccessArticle

Numerical and Experimental Analysis of the Noise Generated in a Ducted Cavity Working in Various Conditions

by Sebastian Rulik, Włodzimierz Wróblewski and Krzysztof Rusin

Energies 2021, 14(22), 7545; https://doi.org/10.3390/en14227545 - 11 Nov 2021

Viewed by 1965

Abstract

Flow over a cavity or a gap may induce pressure fluctuations that are emitted as sound waves and perceived by a human as noise. This phenomenon may occur in different kinds of industrial machines or in everyday life devices, e.g., cars. For this [...] Read more.

Flow over a cavity or a gap may induce pressure fluctuations that are emitted as sound waves and perceived by a human as noise. This phenomenon may occur in different kinds of industrial machines or in everyday life devices, e.g., cars. For this reason, it is important to predict the flow conditions that intensify or attenuate the noise. This research paper presents the numerical and experimental analysis of the pressure fluctuations in a deep, ducted cavity. The experimental test stand made it possible to investigate the flow over a cavity with air velocity in the range of 30–80 m/s. The pressure fluctuations were measured using miniature microphones located in the duct and the cavity wall and processed with LabView software. The phenomena were also analysed using the computational fluid dynamics (CFD) technique. The several modelling approaches were tested and validated against the experimental data. The highest sound pressure levels were obtained for 40 and 70 m/s. The sound frequency increased with the flow velocity. Full article

(This article belongs to the Special Issue Turbomachinery, Energy and Environmental Technologies)

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16 pages, 759 KiB

Open AccessArticle

Development of a Multi-Segment Parallel Compressor Model for a Boundary Layer Ingesting Fuselage Fan Stage

by Jonas Voigt and Jens Friedrichs

Energies 2021, 14(18), 5746; https://doi.org/10.3390/en14185746 - 13 Sep 2021

Cited by 3 | Viewed by 2015

Abstract

The present methodological study aims to assess boundary layer ingestion (BLI) as a promising method to improve propulsion efficiency. BLI utilizes the low momentum inflow of the wing or fuselage boundary layer for thrust generation in order to minimize the required propulsive power [...] Read more.

The present methodological study aims to assess boundary layer ingestion (BLI) as a promising method to improve propulsion efficiency. BLI utilizes the low momentum inflow of the wing or fuselage boundary layer for thrust generation in order to minimize the required propulsive power for a given amount of thrust for wing or fuselage-embedded engines. A multi-segment parallel compressor model (PCM) is developed to calculate the power saving from full annular BLI as occurring at a fuselage tail center-mounted aircraft engine, employing radially subdivided fan characteristics. Applying this methodology, adverse effects on the fan performance due to varying inlet distortions depending on flight operating point as well as upstream boundary layer suction can be taken into account. This marks one step onto a further segmented PCM model for general cases of BLI-induced inlet distortion and allows the evaluation of synergies between combined BLI and active laminar flow control as a drag reduction measure. This study, therefore, presents one further step towards lower fuel consumption and, hence, a lower environmental impact of future transport aircraft. Full article

(This article belongs to the Special Issue Turbomachinery, Energy and Environmental Technologies)

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18 pages, 4958 KiB

Open AccessArticle

Performance Study of a Bladeless Microturbine

by Krzysztof Rusin, Włodzimierz Wróblewski, Sebastian Rulik, Mirosław Majkut and Michał Strozik

Energies 2021, 14(13), 3794; https://doi.org/10.3390/en14133794 - 24 Jun 2021

Cited by 11 | Viewed by 2299

Abstract

The paper presents a comprehensive numerical and experimental analysis of the Tesla turbine. The turbine rotor had 5 discs with 160 mm in diameter and inter-disc gap equal to 0.75 mm. The nozzle apparatus consisted of 4 diverging nozzles with 2.85 mm in [...] Read more.

The paper presents a comprehensive numerical and experimental analysis of the Tesla turbine. The turbine rotor had 5 discs with 160 mm in diameter and inter-disc gap equal to 0.75 mm. The nozzle apparatus consisted of 4 diverging nozzles with 2.85 mm in height of minimal cross-section. The investigations were carried out on air in subsonic flow regime for three pressure ratios: 1.4, 1.6 and 1.88. Maximal generated power was equal to 126 W and all power characteristics were in good agreement with numerical calculations. For each pressure ratio, maximal efficiency was approximately the same in the experiment, although numerical methods proved that efficiency slightly dropped with the increase of pressure ratio. Measurements included pressure distribution in the plenum chamber and tip clearance and temperature drop between the turbine’s inlet and the outlet. For each pressure ratio, the lowest value of the total temperature marked the highest efficiency of the turbine, although the lowest static temperature was shifted towards higher rotational speeds. The turbine efficiency could surpass 20% assuming the elimination of the impact of the lateral gaps between the discs and the casing. The presented data can be used as a benchmark for the validation of analytical and numerical models. Full article

(This article belongs to the Special Issue Turbomachinery, Energy and Environmental Technologies)

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21 pages, 24578 KiB

Open AccessArticle

Experimental Validation of the Aerodynamic Performance of an Innovative Counter-Rotating Centrifugal Compressor

by Cheikh Brahim Abed, Sofiane Khelladi, Michael Deligant, Abdellatif El Marjani, Moisés Solis and Farid Bakir

Energies 2021, 14(9), 2582; https://doi.org/10.3390/en14092582 - 30 Apr 2021

Cited by 1 | Viewed by 2761

Abstract

Turbomachinery with double counter-rotating impellers offers more degrees of freedom in the choice of design and control parameters compared to conventional machines. For these innovative machines, the literature review shows that more publications concerning axial type turbomachines are available than centrifugal ones. This [...] Read more.

Turbomachinery with double counter-rotating impellers offers more degrees of freedom in the choice of design and control parameters compared to conventional machines. For these innovative machines, the literature review shows that more publications concerning axial type turbomachines are available than centrifugal ones. This work deals with a design and experimental performance analysis, applied to two counter-rotating impellers of a centrifugal compressor “CRCC”. CRCC was designed with a specifically developed tool based on mean-line approach coupled with optimization algorithms and a stream-curvature through-flow method to satisfy the design criteria. This paper presents an experimental validation of the CRCC design tool and its performances against the baseline “SR”, composed of one centrifugal impeller and a volute for which experimental data are available. CRCC numeric simulations are also validated by experimental data. For a fair comparison between CRCC and SR, the same volute is used for both configurations. The CRCC studied here includes a first conventional impeller with an axial inlet and a radial outlet, while the second impeller is parametrically designed and can be considered a rotating bladed diffuser with a radial inlet and outlet. The obtained results show that CRCC can deliver a pressure rise increase of two compared to SR, along with an increase of isentropic efficiency and also validate the design method of this novel layout. The experimental results also show that the speed ratio of CRCC has a positive effect on the surge and shock margin. Full article

(This article belongs to the Special Issue Turbomachinery, Energy and Environmental Technologies)

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