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Selected Turbomachinery Papers from the 18th Conference on Modelling Fluid...
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Selected Turbomachinery Papers from the 18th Conference on Modelling Fluid Flow CMFF'22

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

Deadline for manuscript submissions: closed (2 May 2023) | Viewed by 11061

Special Issue Editors

Prof. Dr. János Gábor Vad

E-Mail Website1 Website2
Guest Editor
Department of Fluid Mechanics, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, 1111 Budapest, Hungary
Interests: turbomachinery design; radial stacking techniques; controlled vortex design; turbomachinery aerodynamics and aeroacoustics
Dr. Csaba Horváth

E-Mail Website1 Website2
Guest Editor
Department of Fluid Mechanics, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, 1111 Budapest, Hungary
Interests: turbomachinery aerodynamics and aeroacoustics; beamforming; fans; counter-rotating open rotors
Dr. Tamás Benedek

E-Mail Website1 Website2
Guest Editor
Department of Fluid Mechanics, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, 1111 Budapest, Hungary
Interests: aerodynamics and aeroacoustics of turbomachinery; numerical simulation

Special Issue Information

Dear Colleagues,

It is our privilege to present you with this Special Issue dedicated to CMFF’22. The Special Issue will be a collection of the best turbomachinery papers presented at the Conference on Modelling Fluid Flow (CMFF’22) in Budapest, Hungary, between August 30th and September 2nd, 2022. CMFF’22 is the latest event in the series of international conferences on fluid machinery held in Budapest since 1959. The aim of CMFF is to respond to challenges in the rapidly developing fields of fluid mechanics: the numerical simulation of flows and the physical modelling of flow processes using advanced measurement methods. While the scope of the more recent conferences in the series covers a broader range of key subjects within fluid mechanics, there has and always will be a strong turbomachinery presence at the conference, with CMFF’22 being no different.

Prof. Dr. János Gábor Vad
Dr. Csaba Horváth
Dr. Tamás Benedek
Guest Editors

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.

Published Papers (7 papers)

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Research

16 pages, 6117 KiB  
Article
Comparison Study of the k − kL − ω and γ − Reθ Transition Model in the Open-Water Performance Prediction of a Rim-Driven Thruster
by Bao Liu, Maarten Vanierschot and Frank Buysschaert
Int. J. Turbomach. Propuls. Power 2024, 9(1), 2; https://doi.org/10.3390/ijtpp9010002 - 09 Jan 2024
Viewed by 1370
Abstract
The present work examines the capabilities of two transition models implemented in ANSYS Fluent in the open-water performance prediction of a rim-driven thruster (RDT). The adopted models are the three-equation k−kL−ω and the four-equation [...] Read more.
The present work examines the capabilities of two transition models implemented in ANSYS Fluent in the open-water performance prediction of a rim-driven thruster (RDT). The adopted models are the three-equation k−kL−ω and the four-equation γ−Reθ models. Both of them are firstly tested on a ducted propeller. The numerical results are compared with available experimental data, and a good correlation is found for both models. The simulations employing two transition models are then carried out on a four-bladed rim-driven thruster model and the results are compared with the SST k−ω turbulence model. It is observed that the streamline patterns on the blade surface are significantly different between the transition and fully turbulent models. The transition models can reveal the laminar region on the blade while the fully turbulent model assumes the boundary layer is entirely turbulent, resulting in a considerable difference in torque prediction. It is noted that unlike the fully turbulent model, the transition models are quite sensitive to the free-stream turbulence quantities such as turbulent intensity and turbulent viscosity ratio, as these quantities determine the onset of the transition process. The open-water performance of the studied RDT and resolved flow field are also presented and discussed. Full article
(This article belongs to the Special Issue Selected Turbomachinery Papers from the 18th Conference on Modelling Fluid Flow CMFF'22)
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12 pages, 4371 KiB  
Article
Suitability of a Profile with Tubercles for Axial Pumps—Investigation Using Flow Simulation
by Mareen Derda, Ferdinand Neumann and Paul Uwe Thamsen
Int. J. Turbomach. Propuls. Power 2023, 8(3), 29; https://doi.org/10.3390/ijtpp8030029 - 01 Sep 2023
Viewed by 818
Abstract
Even if wind tunnel tests and simulations have confirmed that tubercles can influence the behaviour of a profile, research in the field of axial pumps has so far been lacking. However, previous studies cannot be transferred to the application of axial pumps, since [...] Read more.
Even if wind tunnel tests and simulations have confirmed that tubercles can influence the behaviour of a profile, research in the field of axial pumps has so far been lacking. However, previous studies cannot be transferred to the application of axial pumps, since the requirements for the profile geometry as well as the Reynolds number range differ. The present study aims to address this research gap by performing a CFD simulation with a profile common for axial pumps, the Goe11K, testing four different tubercle configurations. At the same time, this simulation is a preliminary study for experimental tests. The results show that certain tubercle configurations improve the behaviour of the profile in the post-stall area, i.e., increase the lift of the profile at large angles of attack (α). In general, the curve of the profiles with tubercles runs more evenly, without the drastic drop in lift. This improved property comes at the expense of lower maximum lift and increased drag at lower α. With regard to the use of axial pumps, it can be concluded that there are advantages, particularly in the partial load range. These could ultimately enlarge the operation range of an axial pump. Full article
(This article belongs to the Special Issue Selected Turbomachinery Papers from the 18th Conference on Modelling Fluid Flow CMFF'22)
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13 pages, 3851 KiB  
Article
Development of Sewage Pumps with Numerical and Experimental Support
by David Beck and Paul Uwe Thamsen
Int. J. Turbomach. Propuls. Power 2023, 8(2), 18; https://doi.org/10.3390/ijtpp8020018 - 02 Jun 2023
Cited by 1 | Viewed by 1272
Abstract
Especially in the field of sewage pumps, the design of radial impellers focuses not only on maximum efficiency but also on functionality in terms of susceptibility to clogging by fibrous media. In general, the efficiency of sewage impellers is significantly lower than that [...] Read more.
Especially in the field of sewage pumps, the design of radial impellers focuses not only on maximum efficiency but also on functionality in terms of susceptibility to clogging by fibrous media. In general, the efficiency of sewage impellers is significantly lower than that of clear water impellers. These sewage impellers are designed with a low number of blades to ensure that fibrous media can be pumped. This paper describes the methodology of an optimisation for a sewage impeller. The optimisation is carried out on a semi-open two-channel impeller as an example. Therefore, a new impeller is designed for a given volute casing. Based on a basic design for given boundary conditions, the impeller is verified by means of numerical simulation. The manufactured impeller is then tested on the test rig to verify the simulation. With regard to the optical investigations, the clogging behaviour of the impeller is specifically improved over three different modifications in order to finally present an impeller with good efficiency and a low clogging tendency. Full article
(This article belongs to the Special Issue Selected Turbomachinery Papers from the 18th Conference on Modelling Fluid Flow CMFF'22)
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10 pages, 3373 KiB  
Article
Effects of Tip Leakage Vortex Cavitation on Flow Field under Cavitation Instability
by Youngkuk Yoon and Seung Jin Song
Int. J. Turbomach. Propuls. Power 2023, 8(2), 17; https://doi.org/10.3390/ijtpp8020017 - 01 Jun 2023
Viewed by 1107
Abstract
Cavitation instabilities can induce axial and circumferential vibrations, as well as noise in turbopump inducers. Therefore, the purpose of the present study is to investigate the mechanism of cavitation instability. The flow field near the two-bladed inducer leading edge under alternate blade cavitation [...] Read more.
Cavitation instabilities can induce axial and circumferential vibrations, as well as noise in turbopump inducers. Therefore, the purpose of the present study is to investigate the mechanism of cavitation instability. The flow field near the two-bladed inducer leading edge under alternate blade cavitation was experimentally investigated using particle image velocimetry (PIV). It was found that the tip leakage vortex cavitation draws the flow toward its region of collapse and induces a negative change in the incidence to the adjacent blade. Moreover, this blade-to-blade interaction was identified as the main cause of alternate blade cavitation. Furthermore, it was demonstrated that this blade-to-blade interaction is strongest when the cavity collapse occurs in the inducer throat area, where the leading edge of the following blade is located. Full article
(This article belongs to the Special Issue Selected Turbomachinery Papers from the 18th Conference on Modelling Fluid Flow CMFF'22)
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9 pages, 1966 KiB  
Article
Numerical Analysis of the Flow by Using a Free Runner Downstream the Francis Turbine
by Alin Ilie Bosioc, Raul-Alexandru Szakal, Adrian Stuparu and Romeo Susan-Resiga
Int. J. Turbomach. Propuls. Power 2023, 8(2), 14; https://doi.org/10.3390/ijtpp8020014 - 04 May 2023
Cited by 1 | Viewed by 1387
Abstract
The current requirements of industrialized countries require the use of as much renewable energy as possible. One significant problem with renewable energy is that the produced power fluctuates. Currently, the only method available for energy compensation in the shortest time is given by [...] Read more.
The current requirements of industrialized countries require the use of as much renewable energy as possible. One significant problem with renewable energy is that the produced power fluctuates. Currently, the only method available for energy compensation in the shortest time is given by hydroelectric power plants. Instead, hydroelectric power plants (especially the plants equipped with hydraulic turbines with fixed blades) are designed to operate in the vicinity of the optimal operating point with a maximum ±10% deviation. The energy market requires that hydraulic turbines operate in an increasingly wide area between −35% to 20% from the optimum operating point. Operation of hydraulic turbines far from the optimum operating point involves the appearance downstream of the turbine of a decelerated swirling flow with hydraulic instabilities (known in the literature as the vortex rope). The main purpose of this paper is to investigate numerically a new concept by using a free runner downstream on the main hydraulic runner turbine more precisely in the draft tube cone. The free runner concept requires rotations at the runaway speed with vanishing mechanical torque. The main purpose is to redistribute the total pressure and the moment between the shaft and the periphery. In addition, the free runner does not modify the operating point of the main hydraulic turbine runner. Full article
(This article belongs to the Special Issue Selected Turbomachinery Papers from the 18th Conference on Modelling Fluid Flow CMFF'22)
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8 pages, 3260 KiB  
Article
Leading Edge Bumps for Flow Control in Air-Cooled Condensers
by Lorenzo Tieghi, Giovanni Delibra, Johan van der Spuy and Alessandro Corsini
Int. J. Turbomach. Propuls. Power 2023, 8(1), 9; https://doi.org/10.3390/ijtpp8010009 - 09 Mar 2023
Cited by 1 | Viewed by 1847
Abstract
Air-cooled condensers (ACCs) are commonly found in power plants working with concentrated solar power or in steam power plants operated in regions with limited water availability. In ACCs, the flow of air is driven toward the heat exchangers by axial fans that are [...] Read more.
Air-cooled condensers (ACCs) are commonly found in power plants working with concentrated solar power or in steam power plants operated in regions with limited water availability. In ACCs, the flow of air is driven toward the heat exchangers by axial fans that are characterized by large diameters and operate at very high mass flow rates with a near-zero static pressure rise. Given the overall requirements in steam plants, these fans are subjected to inflow distortions, unstable operations, and are characterized by high noise emissions. Previous studies show that leading edge bumps in the tip region of axial fans can effectively reduce the sound pressure levels without affecting the static efficiency. Nevertheless, the effects of this treatment in terms of flow patterns and heat exchange in the whole ACC system were not investigated. In this work, the effect of leading edge bumps on the flow patterns is analyzed. Two RANS simulations were carried out using OpenFOAM on a simplified model of the air-cooled condenser. The fans are simulated using a frozen rotor approach. Turbulence modeling relies on the RNG k-epsilon model. The fan is characterized by a diameter of 7.3 m and a 333 m3/s volumetric flow rate at the design point. The presence of the heat exchanger is modeled using a porous medium. The comparison between the flow fields clearly exerts that the modified blade is responsible for the redistribution of radial velocities in the rotor region. This drastically reduces the losses related to the installation of the fan in a real configuration. Full article
(This article belongs to the Special Issue Selected Turbomachinery Papers from the 18th Conference on Modelling Fluid Flow CMFF'22)
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15 pages, 8504 KiB  
Article
Transient 3D CFD Simulation of a Pelton Turbine—A State-of-the-Art Approach for Pelton Development and Optimisation
by Lukas Sandmaier, Peter Meusburger and Helmut Benigni
Int. J. Turbomach. Propuls. Power 2023, 8(1), 10; https://doi.org/10.3390/ijtpp8010010 - 09 Mar 2023
Cited by 3 | Viewed by 2642
Abstract
The complex flow conditions in Pelton turbines make it challenging to gain detailed insight into the local flow processes. However, CFD methods offer vast potential for developing and optimising Pelton turbines due to these flow conditions. In a comprehensive examination, a six-nozzle prototype [...] Read more.
The complex flow conditions in Pelton turbines make it challenging to gain detailed insight into the local flow processes. However, CFD methods offer vast potential for developing and optimising Pelton turbines due to these flow conditions. In a comprehensive examination, a six-nozzle prototype Pelton turbine with 19 buckets has been investigated using 3D CFD simulations. First, the steady simulations of the manifold and the unsteady runner simulation have been performed with a mesh-based, commercial CFD code, whereby a two-equation turbulence model and the homogeneous two-phase model were used. Then, to limit the simulation time, symmetry was applied in the runner simulation, and also a strategic definition of the mesh element size in selected blocks of higher interest. Subsequently, the simulation results were analysed. Based on the first simulation results, the geometry of the distributor was modified in an iterative process to reduce losses and improve the jet shape. For the improvement of the latter, a characteristic number was introduced to quantify the secondary flows upstream of the nozzles, which act negatively on the jet shape. Furthermore, the results of the runner simulation were analysed with special regard to the jet-bucket interaction from the start to the end of the impingement cycle of a particular bucket. Finally, a potential efficiency increase could be derived from the summary. Full article
(This article belongs to the Special Issue Selected Turbomachinery Papers from the 18th Conference on Modelling Fluid Flow CMFF'22)
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