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A special issue of International Journal of Turbomachinery, Propulsion and Power (ISSN 2504-186X).

Deadline for manuscript submissions: closed (31 October 2022) | Viewed by 38959

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Special Issue Editor

Prof. Dr. Thomas Carolus

E-Mail Website1 Website2
Guest Editor

1. Steinbeis-Transfer Center FLOWTRANS, 57250 Netphen, Germany
2. Chair of Applied Fluid Mechanics and Turbomachinery, Universität Siegen, 57068 Siegen, Germany
Interests: aerodynamics and aeroacoustics of isothermal turbomachinery (incompressible gases); industrial fans; wind turbines; turbines for ocean energy harvesting (wave and tidal); dynamic models of systems
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Special Issue Information

Dear Colleagues,

The design of industrial fans has evolved to meet the ever-increasing demands for higher-efficiency machines, combined with the requirements for lower noise and high availability. Numerical simulation techniques are important parts of the aerodynamic and acoustic design process and are increasingly coupled to optimization methods. In addition, connectivity, the Internet of Things and digitalization in general open up new opportunities for the highly efficient, low-noise and safe operation of fans in complex systems.

The aim of this Special Issue is to promote the recent advances in fan technology and provide insights into the development and operation of industrial fans for a wide range of applications.

The paper submissions for this Special Issue are welcome to cover some of the following aspects, as well as other related topics:

The development of analytical and computational aerodynamic methods;
Emerging advanced fan design methodologies;
The application of analytical and computational methods for fan analysis, design and optimization;
Structural mechanical aspects (vibration, fatigue and flutter, preventive maintenance, condition monitoring, predictive maintenance);
Experimental methods in fan analysis;
Flow-induced and structure-borne fan noise;
Methods of sound source localization in fans;
Aeroacoustic models and computational (aero)acoustic methods;
Psychoacoustics: product sound quality, perception of annoyance;
Compliance with legislation and regulations;
Connectivity technologies and digital services;
Fan system effect.

Papers submitted for this Special Issue are also expected to come from the 4th International Conference FAN2022, scheduled to take place in June 2022 in Senlis, France.

Prof. Dr. Thomas Carolus
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. International Journal of Turbomachinery, Propulsion and Power is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

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Published Papers (13 papers)

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Editorial

Jump to: Research

1 pages, 141 KiB

Open AccessEditorial

Fans: Noise, Aerodynamics, Applications and Systems—The Best of the International Conference FAN2022

by Thomas H. Carolus

Int. J. Turbomach. Propuls. Power 2022, 7(4), 36; https://doi.org/10.3390/ijtpp7040036 - 2 Dec 2022

Viewed by 1808

Abstract

The number of air- and gas-handling fans in use today is large [...] Full article

(This article belongs to the Special Issue Fan Noise, Aerodynamics, Applications and Systems)

Research

Jump to: Editorial

12 pages, 24958 KiB

Open AccessEditor’s ChoiceArticle

Aeroacoustic Simulations of an Axial Fan with Modelled Turbulent Inflow Conditions

by Philipp Dietrich and Marc Schneider

Int. J. Turbomach. Propuls. Power 2023, 8(2), 13; https://doi.org/10.3390/ijtpp8020013 - 18 Apr 2023

Cited by 3 | Viewed by 2714

Abstract

In applications, the acoustics of fans can differ significantly from the measurements of the standalone fan. This is due to disturbed inflow conditions, for example, caused by a heat exchanger upstream of an axial fan. Resolving the complex geometry and dimensions of typical heat exchangers in aeroacoustic scale-resolving simulations leads to a very high computation effort, which is currently not economically feasible. Turbulence reconstruction tools, such as the FRPM, provide the possibility to model the turbulent inflow conditions, thereby avoiding the representation of the heat exchanger in the aeroacoustic simulations. This approach is tested on a benchmark experiment of a ducted fan with an upstream turbulence grid. Full article

(This article belongs to the Special Issue Fan Noise, Aerodynamics, Applications and Systems)

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10 pages, 3887 KiB

Open AccessArticle

Optimization, Control, and Design of Arbitrarily Shaped Fan Arrays

by Daniel Conrad, Jonathan Mayer and Erik Reichert

Int. J. Turbomach. Propuls. Power 2023, 8(2), 12; https://doi.org/10.3390/ijtpp8020012 - 6 Apr 2023

Viewed by 2083

Abstract

In many air conditioning applications fan arrays offer an increasingly popular alternative to single large fans due to redundancy and ease of maintainability. Additionally, there is the possibility to dynamically resize the array by selectively turning off a number of fans. In this work, a new method for the optimal control of such fan arrays is derived with the goal to minimize the overall power consumption, i.e., maximizing the system efficiency. The approach is universal in the sense that a fan array can be composed of any number, size, and type of fans or mixtures thereof. We explore the achievable power savings for a real world example by applying the method. Moreover, we give an outline of the optimal design of fan arrays and future work. Full article

(This article belongs to the Special Issue Fan Noise, Aerodynamics, Applications and Systems)

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12 pages, 5011 KiB

Open AccessEditor’s ChoiceArticle

Multi-Point, Multi-Objective Optimisation of Centrifugal Fans by 3D Inverse Design Method

by Jiangnan Zhang and Mehrdad Zangeneh

Int. J. Turbomach. Propuls. Power 2023, 8(1), 8; https://doi.org/10.3390/ijtpp8010008 - 2 Mar 2023

Cited by 2 | Viewed by 2581

Abstract

In this paper, we present the design and optimization of a centrifugal fan with requirements of maximizing the total-to-static pressure rise and total-to-static efficiency at two operating points and the maximum torque provided by the motor power using a 3D inverse design method, a DOE (design of experiment) study, an RSM (response surface model) and a MOGA (multi-objective genetic algorithm). The fan geometry is parametrized using 13 design parameters, and 120 different designs are generated. The fan performances of all the designs at two operating conditions are evaluated through steady-state CFD simulations. The resulting design matrix is used to create an RSM based on the Kriging method and MOGA is used to search the design space using the RSM and find the optimal design. Full article

(This article belongs to the Special Issue Fan Noise, Aerodynamics, Applications and Systems)

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11 pages, 1414 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Axial Impeller-Only Fans with Optimal Hub-to-Tip Ratio and Blades Adapted for Minimum Exit Loss

by Thomas Carolus and Konrad Bamberger

Int. J. Turbomach. Propuls. Power 2023, 8(1), 7; https://doi.org/10.3390/ijtpp8010007 - 1 Mar 2023

Cited by 5 | Viewed by 5980

Abstract

This study targets determining impellers of impeller-only axial fans with an optimal hub-to-tip ratio for the highest achievable total-to-static efficiency. Differently from other studies, a holistic approach is chosen. Firstly, the complete class of these fans is considered. Secondly, the radial distribution of blade sweep angle, stagger angle, chord length, and camber are varied to adapt the blades to the complex flow in the hub and tip regions. The tool being used is an optimization scheme with three key components: (i) a database created beforehand by Reynolds-averaged Navier–Stokes (RANS)-predicted performance characteristics of 14,000 designs, (ii) an artificial neural network as a metamodel for the fan performance as a function of 26 geometrical parameters, and (iii) an evolutionary algorithm for optimization, performed on the metamodel. Typically, the hub-to-tip ratios for the impellers proposed by the optimization scheme are smaller than those obtained by applying the classic design rules. A second outcome are the shapes of the blades, which are adapted for a minimum exit loss. These shapes deviate substantially from the classic and even the state-of-the-art “swept-only” or “swept with dihedral” designs. The chord length, stagger, and sweep angle are distributed from hub to tip in a complex manner. The inherent reason is that the scheme tries to minimize not only the dynamic exit loss but also frictional losses due to secondary flows in the hub and tip regions, which eventually results in the maximum achievable total-to-static efficiency. Upon request, the authors will provide the full geometry of the four impellers analysed in some detail in this study to any individual for experimental validation or further analysis of their performance. Full article

(This article belongs to the Special Issue Fan Noise, Aerodynamics, Applications and Systems)

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9 pages, 1308 KiB

Open AccessEditor’s ChoiceArticle

Exergy-Based Efficiency Assessment of Fans vs. Isentropic Efficiency

by Johannes Brötz, Christian Schänzle and Peter F. Pelz

Int. J. Turbomach. Propuls. Power 2023, 8(1), 4; https://doi.org/10.3390/ijtpp8010004 - 6 Feb 2023

Viewed by 3126

Abstract

The efficiency definition allows us to compare two machines with each other. In general, the efficiency is defined as the ratio of usable power to the required power. This raises the question: what is the usable power? Most engineers discuss efficiency on the basis of the energy balance, i.e., the first law of thermodynamics. In this paper, we derive the exegetic efficiency taking the second law of thermodynamics into account. Exergy analysis takes into account work and heat and is able to model reality very accurately. On this basis, a comparison between the isentropic and exergetic efficiencies is given. A high-pressure radial fan is used as an example, and the differences are discussed. Therefore, measurements of a non-adiabatic fan are evaluated, and the role of the heat flux in the environment is discussed. The investigations show that a relevant difference between the isentropic and exergetic efficiencies becomes apparent in the partial-load range with high-pressure build-up. The thermal energy contained in the flow belongs proportionally to the exergy, i.e., the working capacity of the gas relative to its environment. For a standard such as ISO 5801 “Fans—Performance testing using standardized airways”, the efficiency must not only be physically correct, it must also be simple and practical. Against this background, the outlook of this paper discusses when and which efficiency definition is appropriate and best suited for a standard. Full article

(This article belongs to the Special Issue Fan Noise, Aerodynamics, Applications and Systems)

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17 pages, 7595 KiB

Open AccessEditor’s ChoiceArticle

Active Turbulence Grid-Controlled Inflow Turbulence and Replication of Heat Exchanger Flow Fields in Fan Applications

by Felix Czwielong and Stefan Becker

Int. J. Turbomach. Propuls. Power 2023, 8(1), 1; https://doi.org/10.3390/ijtpp8010001 - 4 Jan 2023

Cited by 5 | Viewed by 2766

Abstract

A novel active turbulence grid of the Institute of Fluid Mechanics at FAU Erlangen-Nuremberg is introduced. The focus of this grid is not on basic investigations of fluid mechanics, as is usually the case with active turbulence grids, but the generation of defined inflow conditions for axial fans. Thus, by means of the active turbulence grid, individual turbulence characteristics in the flow to the fan can be changed; therefore, fundamental interactions between the flow mechanics at the axial fan and the sound radiation can be analyzed. In addition, the replication of the flow fields of heat exchangers by the active turbulence grid is the focus of the investigations. The investigations showed that it is possible to use the active turbulence grid to generate defined inflow conditions for axial fans. It was also possible to reproduce the heat exchanger flow fields both for the mean turbulence values and for the spatial distributions. It was found that the grid induces tonal components due to the drive motors, but also that the inherent noise has no significant influence on the spectrum of the fans under investigation. Based on selected turbulence characteristics, direct correlations were found between the spatial distribution of the turbulence level and sound radiation at the first blade passing frequency of the axial fan. As the variance of the turbulence level increases, the sound radiation of the tonal components becomes more pronounced. The total sound pressure level, however, is mainly determined by the low-frequency broadband sound. A linear relationship between the spatial mean value of the turbulence level and the total sound pressure level was found for the investigated axial fan. Full article

(This article belongs to the Special Issue Fan Noise, Aerodynamics, Applications and Systems)

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10 pages, 4693 KiB

Open AccessFeature PaperArticle

Investigations concerning the Flow Stabilization of Backward Curved Centrifugal Impellers at Low Flow Rate

by Frieder Lörcher, Sandra Hub, Marlène Sanjosé and Stéphane Moreau

Int. J. Turbomach. Propuls. Power 2022, 7(4), 37; https://doi.org/10.3390/ijtpp7040037 - 7 Dec 2022

Viewed by 2131

Abstract

For a backward curved centrifugal fan, reducing volume flow rate from design operating point towards part load yields an increase in noise emission together with a reduction of efficiency. The spectral content of the emerging noise emission can be characterized by a subharmonic hump with several harmonics. Based on narrow-band acoustic measurements and numerical Lattice-Boltzmann simulations, a deeper insight is sought after. Downstream unsteady flow patterns are identified to play a central role in this performance deterioration; and geometrical flow stabilization means are investigated. Full article

(This article belongs to the Special Issue Fan Noise, Aerodynamics, Applications and Systems)

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Graphical abstract

11 pages, 5118 KiB

Open AccessFeature PaperArticle

Uniformity Index as a Universal Air-Cooled Condenser Fan Performance Metric

by Fredrik Marincowitz, Michael Owen, Jacques Muiyser and Peter Holkers

Int. J. Turbomach. Propuls. Power 2022, 7(4), 35; https://doi.org/10.3390/ijtpp7040035 - 1 Dec 2022

Cited by 2 | Viewed by 2833

Abstract

Ambient wind has a negative effect on mechanical forced-draft direct air-cooled steam condenser (ACC) fan volumetric performance, and increases dynamic fan blade loading. Investigating these effects directly using on-site measurement or numerical analysis is complicated, and most previous work has focused on only one effect at the expense of the other. In this study, fan axial velocity inflow uniformity is identified as a single metric offering the potential to holistically qualify ACC fan operation under windy conditions. A 3 × 6 fan cell ACC was modelled with CFD using a blade element theory-based fan model, and clear relationships between the fan inflow uniformity index and both fan volumetric performance and dynamic blade loading were observed in the results. The same relationships were observed in on-site test data collected at a single ACC fan, thus validating the numerical results. The uniformity index can be used in both numerical and experimental work as a means of investigating both fan volumetric performance and dynamic blade loading with less computational and measurement complexity; it also offers a potentially useful means of quantifying the severity of fan operating conditions, to assist with more reliable case-specific fan design and selection. Full article

(This article belongs to the Special Issue Fan Noise, Aerodynamics, Applications and Systems)

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11 pages, 6049 KiB

Open AccessArticle

Effect of Sweep on Axial Fan Noise Sources Using the Lattice Boltzmann Method

by Dipali Ghodake, Marlène Sanjosé, Stéphane Moreau and Manuel Henner

Int. J. Turbomach. Propuls. Power 2022, 7(4), 34; https://doi.org/10.3390/ijtpp7040034 - 22 Nov 2022

Cited by 11 | Viewed by 3994

Abstract

The effect of blade sweep has been studied numerically with the Lattice Boltzmann Method on a family of low-speed free-vortex axial fans with sweeps of ±45°. Good overall aerodynamic agreement is first demonstrated on all fans at the design condition, particularly in the tip gap. The local larger wall-pressure fluctuations seen in the unswept and backward swept fans compared to the forward case are traced to the stronger tip vortices that remain in the rotational plane or even move upstream. These stronger and faster vortices interacting with the fan blades are then responsible for the larger noise levels observed in the acoustic spectra of these fans, and particularly for large subharmonic humps. Excellent agreement between experimental and numerical noise predictions is finally reported stressing the dominant tip noise. Full article

(This article belongs to the Special Issue Fan Noise, Aerodynamics, Applications and Systems)

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Graphical abstract

11 pages, 4709 KiB

Open AccessArticle

Inlet Gap Effect on Tonal Noise Generated from a Voluteless Centrifugal Fan

by Martin Ottersten, Hua-Dong Yao and Lars Davidson

Int. J. Turbomach. Propuls. Power 2022, 7(4), 33; https://doi.org/10.3390/ijtpp7040033 - 18 Nov 2022

Cited by 2 | Viewed by 2302

Abstract

In this study, three voluteless centrifugal fans are compared for their aeroacoustic performances. The tonal noise is predicted by coupling the IDDES with Formulation 1A of Farassat. The sources of the tonal noise at the blade passing frequency (

B P F

) [...] Read more.

B P F

) are identified. It is found that the sources are related to the fan inlet gap, which introduces higher velocity intensities and turbulent fluctuations interacting with the blade leading edge. By redesigning the gap, the tonal noise at the

B P F

is reduced effectively. Full article

(This article belongs to the Special Issue Fan Noise, Aerodynamics, Applications and Systems)

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11 pages, 2535 KiB

Open AccessFeature PaperArticle

Evaluation of the Wear-Resistant Plate Performance on Different Locations over the Flow Path of a Large-Sized Heavy-Duty Centrifugal Fan

by Nicola Aldi, Nicola Casari, Michele Pinelli, Alessio Suman, Alessandro Vulpio, Ottavio Mantovani and Paolo Saccenti

Int. J. Turbomach. Propuls. Power 2022, 7(4), 32; https://doi.org/10.3390/ijtpp7040032 - 17 Nov 2022

Viewed by 2253

Abstract

In industrial applications such as chemical plants, cement factories, and glassmakers, large-sized centrifugal fans are commonly used for dust-laden flow processing. In many cases, the contamination is due to solid particles responsible for fouling and erosion issues. Erosion induces the reduction of mechanical resistance and, at the same time, the modification of the geometry and the surface characteristics of the internal flow path. The process works according to the characteristics of the erodent particles, such as dimension and hardness, which have to be coupled with the mechanical properties of the substrate, like hardness and roughness level. In addition to this, the intensity of the erosion depends on the dynamic characteristics of particles, especially velocity and impact angle. For these reasons, erosion-related issues are difficult predict and reduce. In an attempt to preserve the structural integrity of the internal walls, wear-resistant plates are positioned where the impacting contaminants are supposed to be more detrimental. In the present work, a combined experimental and numerical approach is proposed to evaluate the proper setup of wear-resistance plates over the flow path of a large-sized centrifugal fan. The results show how different regions (rotating and stationary walls) are subjected to different impact behavior, determining that the design of the position of the wear-resistant plate is not straightforward. Suggestions related to reducing the erosion intensity are reported, highlighting the possibility of designing the best compromise between erosion, performance, and costs. Full article

(This article belongs to the Special Issue Fan Noise, Aerodynamics, Applications and Systems)

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8 pages, 4965 KiB

Open AccessFeature PaperArticle

Energy and CO₂ Impact of the Eco-Design Regulation for Fans on the European Market

by Claus Händel

Int. J. Turbomach. Propuls. Power 2022, 7(4), 31; https://doi.org/10.3390/ijtpp7040031 - 16 Nov 2022

Viewed by 1910

Abstract

Fans are components in many different products and have been regulated since 2011 by the Eco-Design Regulation. A fan is typically not a final product but is used as a component in different applications, systems, and products. This study shows that it is helpful to target and regulate a component (possibly additionally) such a fan and that the Eco-Design Regulation of fans is an important driver of energy efficiency and has a significant impact. Regulating fans as a component stimulates the availability of efficient fans at reasonable prices and drives efficiency, also in cases where fans are implemented in other products where a fan’s efficiency does not dominate its performance. Since it was first implemented in 2013, the following savings in electrical energy were achieved: 12 GW electrical power, 150 TWh electrical energy, and 12 MT CO₂. This is significant and a good example for regulation. Full article

(This article belongs to the Special Issue Fan Noise, Aerodynamics, Applications and Systems)

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