Journal Description
International Journal of Turbomachinery, Propulsion and Power
International Journal of Turbomachinery, Propulsion and Power
is an international, peer-reviewed, open access journal on turbomachinery, propulsion and power. The journal is owned by the EUROTURBO European turbomachinery society and is published quarterly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, ESCI (Web of Science), Inspec, and other databases.
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 12 days after submission; acceptance to publication is undertaken in 19.6 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Impact Factor:
1.4 (2022);
5-Year Impact Factor:
1.3 (2022)
Latest Articles
Turbulence Measurements Downstream of a Combustor Simulator Designed for Studies on the Combustor–Turbine Interaction
Int. J. Turbomach. Propuls. Power 2024, 9(1), 4; https://doi.org/10.3390/ijtpp9010004 - 10 Jan 2024
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Turbulence intensity impacts the performance of turbine stages and it is an important inlet boundary condition for CFD computations; the knowledge of its value at the turbine inlet is then of paramount importance. In combustor–turbine interaction experimental studies, combustor simulators replace real combustors
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Turbulence intensity impacts the performance of turbine stages and it is an important inlet boundary condition for CFD computations; the knowledge of its value at the turbine inlet is then of paramount importance. In combustor–turbine interaction experimental studies, combustor simulators replace real combustors and allow for the introduction of flow perturbation at the turbine inlet. Therefore, the turbulence intensity of a combustor simulator used in a wide experimental campaign at Politecnico di Milano is characterized using a hot-wire probe in a blow-down wind tunnel, and the results are compared to URANS CFD computations. This combustor simulator can generate a combination of a swirl profile with a steady/unsteady temperature disturbance. In the cold unsteady disturbance case, hot-wire measurements are phase-averaged at the frequency of the injected perturbation. The combustor simulator turbulence intensity is measured at two different axial positions to understand its evolution.
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Open AccessFeature PaperArticle
An Experimental Database for the Analysis of Bursting of a Laminar Separation Bubble
Int. J. Turbomach. Propuls. Power 2024, 9(1), 3; https://doi.org/10.3390/ijtpp9010003 - 10 Jan 2024
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The bursting phenomenon consists in the switch of a laminar separation bubble from a short to a long configuration. In the former case, reduced effects on profile pressure distribution are typically observed with respect to the attached condition. On the contrary, long bubbles
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The bursting phenomenon consists in the switch of a laminar separation bubble from a short to a long configuration. In the former case, reduced effects on profile pressure distribution are typically observed with respect to the attached condition. On the contrary, long bubbles provoke significant variations in the loading coefficient upstream of the separation position, with increased risk of stall of the lifting surfaces. The present work presents an experimental database describing separated boundary layers evolving under different Reynolds numbers, adverse pressure gradients and free-stream turbulence levels. Overall, more than 80 flow conditions were tested concerning short and long bubbles for the characterization of separated flows under turbine-like conditions. Measurements were performed on a flat plate geometry using a fast-response Particle Image Velocimetry (PIV) system. For each flow case, two sets of 6000 flow records were acquired with an acquisition frequency equal to 300 and 1000 Hz. Based on existing criteria for the identification of the bursting phenomenon, the flow cases were clustered in terms of short and long bubble states. Additionally, the kind of instability (i.e., convective or absolute) developing into the separated boundary layer was identified based on flow statistics. The present data captures the existing link between the bursting of a laminar separation bubble and the onset of the absolute instability of the separated shear layer, with stationary vortices forming in the dead air region.
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Open AccessArticle
Comparison Study of the k − kL − ω and γ − Reθ Transition Model in the Open-Water Performance Prediction of a Rim-Driven Thruster
Int. J. Turbomach. Propuls. Power 2024, 9(1), 2; https://doi.org/10.3390/ijtpp9010002 - 09 Jan 2024
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 and the four-equation
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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 and the four-equation 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 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.
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(This article belongs to the Special Issue Selected Turbomachinery Papers from the 18th Conference on Modelling Fluid Flow CMFF'22)
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Open AccessFeature PaperArticle
Effect of Leading-Edge Erosion on the Performance of Transonic Compressor Blades
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, , , , and
Int. J. Turbomach. Propuls. Power 2024, 9(1), 1; https://doi.org/10.3390/ijtpp9010001 - 09 Jan 2024
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In this paper, an experimental and numerical investigation of the effect of leading-edge erosion in transonic blades was performed. The measurements were carried out on a linear blade cascade in the Transonic Cascade Wind Tunnel of DLR in Cologne at two operating points
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In this paper, an experimental and numerical investigation of the effect of leading-edge erosion in transonic blades was performed. The measurements were carried out on a linear blade cascade in the Transonic Cascade Wind Tunnel of DLR in Cologne at two operating points with an inflow Mach number of 1.05 and 1.12. The numerical simulations were performed by ANSYS Germany. The type and specifications of the erosion for the study were derived from real engine blades and applied to the leading edges of the experimental cascade blades using a waterjet process, as well as modeled in detail and meshed within the numerical setup. Numerical simulations and extensive wake measurements were carried out on the cascades to evaluate the aerodynamic performance. The increase in losses was quantified to be 4 percent, and a reduction in deflection and a rise in pressure were detected at both operating points.
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Open AccessArticle
A Comparison of Steam Turbine Control Valve Geometries and Their Dynamic Behavior at Part Load
Int. J. Turbomach. Propuls. Power 2023, 8(4), 55; https://doi.org/10.3390/ijtpp8040055 - 18 Dec 2023
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A growing significance of flexible steam turbine operation challenges the control of turbines, as part load operation using control valves can be accompanied by highly unsteady flow conditions. The increased dynamic load induced by pressure forces can reduce the reliable operating range, weaken
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A growing significance of flexible steam turbine operation challenges the control of turbines, as part load operation using control valves can be accompanied by highly unsteady flow conditions. The increased dynamic load induced by pressure forces can reduce the reliable operating range, weaken the valve, and lead to mechanical failures. The geometry of the valve plays a major role in the reduction of dynamic forces. Using a scaled control valve, experiments were conducted with a focus on the dynamic behavior of the valve head. A spherical valve shape favoring unstable operation was used as a reference case, and the desired instability was proven by measurements. Different modified valve geometries based on literature featuring separation edges were then tested against the spherical shape. Results indicate the improved stability of the modified geometries over the reference geometry. For most of the operating range, vibrations were drastically reduced, and the overall flow stabilized.
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Open AccessFeature PaperArticle
NREL-5MW Wind Turbine Noise Prediction by FWH-LES
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, , , , and
Int. J. Turbomach. Propuls. Power 2023, 8(4), 54; https://doi.org/10.3390/ijtpp8040054 - 06 Dec 2023
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This paper deals with large onshore wind turbine aeroacoustics. Noise from the NREL 5 MW device is predicted by the permeable-surface Ffowcs Williams–Hawkings equation (FWH-P), starting from the postprocessing of LES data on different acoustic surfaces . Their size and placement is
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This paper deals with large onshore wind turbine aeroacoustics. Noise from the NREL 5 MW device is predicted by the permeable-surface Ffowcs Williams–Hawkings equation (FWH-P), starting from the postprocessing of LES data on different acoustic surfaces . Their size and placement is aimed at embedding most of the aerodynamic sources of sound surrounding rotor and nacelle. Due to the presence of eddies that inevitably cross , this paper compares results from open and closed acoustic surfaces, and the outflow disk averaging technique. The issues related to the interpolation process of LES data on is discussed as well. In order to assess the LES/FWH-P aeroacoustic platform, LES and FWH-P pressures are compared in the very-near field. It is shown that, within the limits of the discretization settings imposed by the interpolation procedure and for the Reynolds number working condition investigated herein, the lack of quadrupole sources outside the permeable surface(s) deeply affect the quality of FWH-P acoustic pressures with respect to direct LES signals.
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Open AccessArticle
Fan Stage Design and Performance Optimization for Low Specific Thrust Turbofans
Int. J. Turbomach. Propuls. Power 2023, 8(4), 53; https://doi.org/10.3390/ijtpp8040053 - 04 Dec 2023
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In modern turbofan engines, the bypass section of the fan stage alone provides the majority of the total thrust required in cruise, and the size of the fan has a considerable effect on the overall engine weight and nacelle drag. Thrust requirements in
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In modern turbofan engines, the bypass section of the fan stage alone provides the majority of the total thrust required in cruise, and the size of the fan has a considerable effect on the overall engine weight and nacelle drag. Thrust requirements in different parts of the flight envelope must also be satisfied together with sufficient margins towards stalling. An accurate description of the interdependencies between the relevant performance and design attributes of the fan stage alone—such as efficiency, surge margin, fan-face Mach number, stage loading, flow coefficient, and aspect ratio—are therefore necessary to estimate system-level objectives such as mission fuel burn and the direct operating cost with enough confidence during the conceptual design phase. The contribution of this study is to apply a parametric optimization approach to the conceptual design of fan stages for low specific thrust turbofans based on the streamline curvature method. Trade-offs between fan stage attributes for Pareto-optimal solutions are modeled by training Kriging surrogate models on the results from the parametric optimization. A case study is provided in the end to demonstrate the potential implications of including a higher level of fan-stage parameter interdependency in an engine systems model. Results implied that being able to predict the rotor solidity required to maintain a given average blade loading—in addition to stage efficiency—is of significant importance when it comes to evaluating the trade-off between engine weight and thrust-specific fuel consumption.
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Open AccessArticle
Numerical Modelling of the 3D Unsteady Flow of an Inlet Particle Separator for Turboshaft Engines
Int. J. Turbomach. Propuls. Power 2023, 8(4), 52; https://doi.org/10.3390/ijtpp8040052 - 04 Dec 2023
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Helicopter and turboprop engines are susceptible to the ingestion of debris and other foreign objects, especially during take-off, landing, and hover. To avoid deleterious effects, filters such as Inlet Particle Separators (IPS) can be installed. However, the performance and limitations of these systems
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Helicopter and turboprop engines are susceptible to the ingestion of debris and other foreign objects, especially during take-off, landing, and hover. To avoid deleterious effects, filters such as Inlet Particle Separators (IPS) can be installed. However, the performance and limitations of these systems have to be investigated before the actual equipment can be installed in the aircraft powerplant. In this paper, we propose different numerical methods with increasing resolution in order to provide an aerodynamic characterization of the IPS, i.e., from a simple semi-empirical model to 3D large eddy simulation. We validate these numerical tools that could aid IPS design using experimental data in terms of global parameters such as separation efficiency and pressure losses. For each of those tools, we underline weaknesses and potential benefits in industry practices. Unsteady flow analysis reveals that detached eddy simulation is the trade-off choice that allows designers to most effectively plan experimental campaigns and mitigate risks.
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Open AccessArticle
Profile Loss Prediction for Organic Rankine Cycle Turbines: An Experimental Case Study
Int. J. Turbomach. Propuls. Power 2023, 8(4), 51; https://doi.org/10.3390/ijtpp8040051 - 01 Dec 2023
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The results of profile loss measurements, including trailing edge flow details, are presented for the flow of an organic vapor through a linear turbine cascade. The so-called VKI-I blade profile from the open literature was chosen for the cascade, and the working fluid
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The results of profile loss measurements, including trailing edge flow details, are presented for the flow of an organic vapor through a linear turbine cascade. The so-called VKI-I blade profile from the open literature was chosen for the cascade, and the working fluid was NOVEC 649. Pitot probes and hot-wire anemometry were employed to measure the flow field up and downstream of the cascade. Details of the unsteady flow caused by the trailing edge of the blades and the turbulent spectrum were investigated using hot-wire anemometry. The new organic vapor flow results were compared with the literature data obtained for air and with the prediction of conventional literature loss models. It was found that, under certain thermodynamic conditions, specific traditional loss models can reasonably predict organic Rankine cycle (ORC) turbines’ profile loss. Still, significant deviations between the loss models and the experimental data can also occur.
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Open AccessArticle
Effect of Porosity and Injection Ratio on the Performance of Transpiration Cooling through Gyroids
Int. J. Turbomach. Propuls. Power 2023, 8(4), 50; https://doi.org/10.3390/ijtpp8040050 - 01 Dec 2023
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This paper presents experimental measurements of adiabatic effectiveness for three transpiration cooling porosities ( 0.3, 0.4, and 0.5) constructed from gyroid lattice structures. To the authors’ knowledge, this is the first use of a Triply Periodic Minimal Surface (TPMS) function to
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This paper presents experimental measurements of adiabatic effectiveness for three transpiration cooling porosities ( 0.3, 0.4, and 0.5) constructed from gyroid lattice structures. To the authors’ knowledge, this is the first use of a Triply Periodic Minimal Surface (TPMS) function to produce transpiration test coupons of varying porosity. Polymer gyroid lattice structures were successfully printed using Stereolithography (SLA) down to 0.3 for a print resolution of 25 microns and unit cell size of 2 mm. Cooling performance was measured in a small-scale wind tunnel. High-resolution Infrared Thermography was used to determine wall temperatures downstream of the porous section. When tested at both common blowing ratios ( = 0.029, 0.048, and 0.062) and common injection ratios ( = 0.010, 0.017, and 0.022) the cooling performance was found to be dependent on porosity for constant but not for constant . Having determined as the more important parameter for comparison, results are presented alongside transpiration and effusion data from literature.
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Open AccessArticle
Experimental and Numerical Investigation of a Turbine Vane Frame with Splitters at Different Operating Points
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Int. J. Turbomach. Propuls. Power 2023, 8(4), 49; https://doi.org/10.3390/ijtpp8040049 - 01 Dec 2023
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A turbine vane frame is a special type of intermediate turbine duct, and is one option to improve the efficiency and reduce the length and weight of an aero-engine. However, due to its geometry, it features a complex flow field, and therefore in-depth
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A turbine vane frame is a special type of intermediate turbine duct, and is one option to improve the efficiency and reduce the length and weight of an aero-engine. However, due to its geometry, it features a complex flow field, and therefore in-depth aerodynamic investigations are necessary. Especially for aviation, every component needs to function reliably during all operating points. To perform this study at the Institute for Thermal Turbomachinery at the Graz University of Technology, the Subsonic Test Turbine Facility for Aerodynamic, Aeroacoustic and Aeroelastic Investigations was equipped with a turbine vane frame and a low-pressure turbine located downstream. Measurements were taken with aerodynamic five-hole probes for three operating points, and were compared with steady-state and transient simulations as well as analytic solutions for the pressure drop in the TVF. Finally, the most important loss mechanisms are described.
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Open AccessArticle
Determination of a Numerical Surge Limit by Means of an Enhanced Greitzer Compressor Model
Int. J. Turbomach. Propuls. Power 2023, 8(4), 48; https://doi.org/10.3390/ijtpp8040048 - 14 Nov 2023
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The surge limit of centrifugal compressors is a key parameter in the design process of modern turbochargers. Numerical methods like steady-state simulations are state-of-the-art methods for predicting the performance of the centrifugal compressor. In contrast to that, the determination of the surge limit
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The surge limit of centrifugal compressors is a key parameter in the design process of modern turbochargers. Numerical methods like steady-state simulations are state-of-the-art methods for predicting the performance of the centrifugal compressor. In contrast to that, the determination of the surge limit with any numerical method is still an unsolved challenge. Since the extensive work of Greitzer and many other researchers in this field, it is well-known that surge is a system-dependent phenomenon. In the case of steady-state simulations, the simulation domain is chosen to be as small as possible due to the numerical cost. This simply implies that there is no system information included in the numerical model. Therefore, it is not possible to determine any system-dependent surge limit with today’s applied numerical methods. To overcome this issue, an enhanced Greitzer surge model, which has been developed at Tu Darmstadt, should act as a link between the simulation and the system in which the compressor will be operated. The focus of this paper will rather be on the methodology of determining the surge limit by means of numerical data than on the surge model itself. The methodology will be validated by experimental data of different systems.
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Open AccessArticle
The Current Gap between Design Optimization and Experiments for Transonic Compressor Blades
Int. J. Turbomach. Propuls. Power 2023, 8(4), 47; https://doi.org/10.3390/ijtpp8040047 - 13 Nov 2023
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The successful design of compressor blades through numerical optimization relies on accurate CFD-RANS solvers that are able to capture the general performance of a given design candidate. However, this is a difficult task to achieve in transonic flow conditions, where the flow is
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The successful design of compressor blades through numerical optimization relies on accurate CFD-RANS solvers that are able to capture the general performance of a given design candidate. However, this is a difficult task to achieve in transonic flow conditions, where the flow is dominated by inherently unsteady shock effects. In order to assess the current gap between numerics and experiments, the DLR has tested the recently optimized Transonic Cascade TEAMAero at the transonic cascade wind tunnel. The tests were performed at a Mach number of 1.2 and with inflow angles between 145 and 147°. The results indicate satisfactory agreement across the expected working range, over which the cascade losses were consistently predicted within a 3–6% error. However, some key differences are observed in the details of the wake and in the performance near the endpoints of the working range. This comparison helps validate the design process but also informs its constraints based on the limitations of CFD-RANS solvers.
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Open AccessArticle
Unsteady Cavitation Analysis of the Centrifugal Pump Based on Entropy Production and Pressure Fluctuation
Int. J. Turbomach. Propuls. Power 2023, 8(4), 46; https://doi.org/10.3390/ijtpp8040046 - 11 Nov 2023
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A numerical method using combined detached-eddy simulation (DES) and a cavitation model considering the rotation effect is used for unsteady cavitation flow field of the centrifugal pump. A closed-type pump test system was established to obtain the pump performance and pressure pulsation characteristics
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A numerical method using combined detached-eddy simulation (DES) and a cavitation model considering the rotation effect is used for unsteady cavitation flow field of the centrifugal pump. A closed-type pump test system was established to obtain the pump performance and pressure pulsation characteristics under different flow rates and cavitation condition, which provide boundary conditions and verification of calculations. Based on the calculation results of the unsteady flow field of the centrifugal pump cavitation, the entropy generation analysis of the flow field and an analysis of the pressure fluctuation characteristics were carried out. Then, we tried to reveal the relationship between cavitation and the deterioration of the centrifugal pump performance and the generation of the unstable operation excitation force. The internal energy loss is mainly concentrated in the impeller, volute, and pump cavity area, which accounts for more than 85% of the total entropy generation. The characteristic frequency of a Strouhal number of about 0.333 appears at the volute tongue due to the cavitation flow spread downstream.
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Open AccessFeature PaperArticle
Lubrication Film Friction Model for Grooved Annular Seals
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Int. J. Turbomach. Propuls. Power 2023, 8(4), 45; https://doi.org/10.3390/ijtpp8040045 - 10 Nov 2023
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Grooved liquid annular seals have a significant influence on the design of turbomachines. Corresponding lubrication film models need to account for the different friction behavior of the grooves compared to plain seals. However, there is a lack of reliable and validated models for
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Grooved liquid annular seals have a significant influence on the design of turbomachines. Corresponding lubrication film models need to account for the different friction behavior of the grooves compared to plain seals. However, there is a lack of reliable and validated models for this purpose. Thus, the applicability of a friction factor model is explored and a calibration method is presented. A single square groove is investigated by means of 96 steady-state RANS simulations for different operation conditions and groove geometries. The results are used to calibrate the friction model and successfully verify it in terms of the pressure drop over the groove. For validation, two full grooved seals with relatively large square grooves were investigated by experiment. The friction model was incorporated in a lubrication model and compared to the measurement data for the pressure difference and the resulting force for specified leakage and eccentricity. The model predictions for the pressure difference can be considered very good. The force predictions show significant deviation, but can be considered acceptable given the low force magnitudes and measurement uncertainty. The results offer a general validity to our friction model approach, assumptions and the calibration method.
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Open AccessArticle
Steady and Unsteady Numerical Characterization of the Secondary Flow Structures of a Highly Loaded Low-Pressure Compressor Stage
Int. J. Turbomach. Propuls. Power 2023, 8(4), 44; https://doi.org/10.3390/ijtpp8040044 - 10 Nov 2023
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This paper presents the numerical characterization of a highly loaded compressor by means of 3D unsteady RANS simulations. The focus is on critical flow structures and their evolution at different operating points of the machine. First, the numerical setup and mesh quality are
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This paper presents the numerical characterization of a highly loaded compressor by means of 3D unsteady RANS simulations. The focus is on critical flow structures and their evolution at different operating points of the machine. First, the numerical setup and mesh quality are presented to support the reliability of the provided results. The comparison against experiments is then described for this purpose. Later, a full description of the unsteady behavior of the machine is provided, giving special attention to the two regions where the most critical features are expected: the rotor hub wall and the casing. Rotor–stator interactions are then investigated and the role of the inlet guide vane (IGV) is finally discussed. Results are analyzed at design and near-stall conditions, with a focus on the behavior close to the stability limit at 100% speed.
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Open AccessArticle
Surrogate Modeling of the Aeroacoustics of an NM80 Wind Turbine
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, , , and
Int. J. Turbomach. Propuls. Power 2023, 8(4), 43; https://doi.org/10.3390/ijtpp8040043 - 20 Oct 2023
Cited by 1
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Wind turbines play a major role in the European Green Deal for clean energy transition. Noise is a critical aspect among open technological issues, as it determines the possibility of onshore installations near inhabited places and the possible detrimental effects on wildlife when
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Wind turbines play a major role in the European Green Deal for clean energy transition. Noise is a critical aspect among open technological issues, as it determines the possibility of onshore installations near inhabited places and the possible detrimental effects on wildlife when offshore. This paper assesses the accuracy of different approaches to predicting the sound pressure level (SPL) of a wind turbine. The 2.75 MW Neg Micon NM80 horizontal axis wind turbine (HWAT) was simulated in OpenFOAM, modeling the turbine with the actuator line method (ALM) implemented in the turbinesFoam library. Two different inflow conditions were considered: a stationary inflow with a typical atmospheric boundary layer profile and a time-dependent inflow derived from a precursor channel with fully turbulent conditions. The surrogate model for noise prediction used for this work is based on the synthetic/surrogate acoustics models (SAMs) of Amiet and Brooks-Pope-Marcolini (BPM). This approach allows for blade motion modeling and the prediction of the SPL of the URANS postprocessing results. The SPL spectrum obtained was then compared to the results from the other aeroacoustic solvers of IEA Task 39 participants, showing the best performance in the fully turbulent case. The results demonstrate that coupling between the ALM and surrogate acoustics provides more accurate results than the blade element momentum (BEM) approach.
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Open AccessReview
State of the Art on Two-Phase Non-Miscible Liquid/Gas Flow Transport Analysis in Radial Centrifugal Pumps Part B: Review of Experimental Investigations
Int. J. Turbomach. Propuls. Power 2023, 8(4), 42; https://doi.org/10.3390/ijtpp8040042 - 13 Oct 2023
Abstract
This paper aims to summarize the results of several experimental investigations regarding two-phase liquid–gas flows in radial centrifugal pumps. The main objective is to combine the corresponding experimental results and collect the obtained knowledge to provide a better understanding of this configuration. The
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This paper aims to summarize the results of several experimental investigations regarding two-phase liquid–gas flows in radial centrifugal pumps. The main objective is to combine the corresponding experimental results and collect the obtained knowledge to provide a better understanding of this configuration. The simultaneous transport of the two phases, the phase segregation, and the regions of safe or critical pump performance were described for a wide variety of pump configurations. This review covers single- and two-phase pumping conditions, performance degradation, pump breakdown, performance hysteresis, different flow regimes, flow regime maps, flow instabilities, and surging. This manuscript also considers the influence of employing different pump configurations on pump performance and flow regimes. This includes comparisons between closed and semi-open impellers, standard and increased tip clearance gaps, and running the pump with and without an inducer. Many of the results discussed have been published in a series of research papers. They were all collected, summarized, and compared systematically in the present review.
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(This article belongs to the Special Issue Advances in Critical Aspects of Turbomachinery Components and Systems)
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Open AccessArticle
Adjoint-Based Design Optimization of a Volute for a Radial Compressor
Int. J. Turbomach. Propuls. Power 2023, 8(4), 41; https://doi.org/10.3390/ijtpp8040041 - 13 Oct 2023
Cited by 1
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Numerical optimization methods are widely used for designing turbomachinery components due to the cost and time savings they can provide. In the available literature, the shape optimization of radial compressors mainly focuses on improving the impeller alone. However, it is well-established knowledge that
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Numerical optimization methods are widely used for designing turbomachinery components due to the cost and time savings they can provide. In the available literature, the shape optimization of radial compressors mainly focuses on improving the impeller alone. However, it is well-established knowledge that the volute plays a key role in the overall performance of the compressor. The aim of the present paper is to perform an adjoint-based optimization of a volute that is designed for the SRV2-O compressor. The CAD model was first created by using the parametrization of 33 design parameters. Then, a butterfly topology was applied to mesh the computational domain with a multi-block structured grid, and an elliptic smoothing procedure was used to improve the quality of the fluid grid. A steady-state RANS CFD solver with a Spalart-Allmaras turbulence model was used to solve the Navier–Stokes equations, and then the flow sensitivities were computed with an adjoint solver. The objective function consists of minimizing the loss coefficient of the volute. The optimization is performed to obtain an improved design with a 14% loss reduction. A detailed flow and design analysis is carried out to highlight the loss reduction mechanisms, followed by the optimizer. Finally, the compressor map of the full stage is compared between the baseline and the optimized volute from the CFD simulations using a mixing plane interface. This research demonstrates the successful use of a gradient-based optimization technique to improve the volute of a radial compressor and opens the door towards simultaneously optimizing the wheel and the volute.
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Open AccessFeature PaperArticle
New Supersonic Nozzle Test Rig Used to Generate Condensing Flow Test Data According to Barschdorff
Int. J. Turbomach. Propuls. Power 2023, 8(4), 40; https://doi.org/10.3390/ijtpp8040040 - 04 Oct 2023
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Considerable progress has been achieved in recent decades in understanding the phenomena related to the onset of condensation in steam flows, both experimentally and especially numerically. Nevertheless, there is still a certain disagreement between the different numerical models used. Unfortunately, the available experimental
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Considerable progress has been achieved in recent decades in understanding the phenomena related to the onset of condensation in steam flows, both experimentally and especially numerically. Nevertheless, there is still a certain disagreement between the different numerical models used. Unfortunately, the available experimental validation data are not sufficiently detailed to allow for proper validation of computational fluid dynamics (CFD) simulations. Therefore, this paper presents new experimental data for condensing steam flows, acquired in a supersonic nozzle according to Barschdorff, at the Institute of Thermal Turbomachinery Laboratory (ITSM) at the University of Stuttgart. A steady inlet pressure of approximately 784 mbar was set for three inlet temperatures down to . Condensation onset is accurately captured across the nozzle, using down to 1 mm spatial resolution for both pneumatic and light spectra measurements. CFD simulations were performed using the commercial solver ANSYS CFX. The droplet diameters are numerically overestimated by approximately a factor of 1.5. Disagreement has been found between original Barschdorff’s experiments and measurements at ITSM. However, there is a good agreement in terms of the pressure distribution along the nozzle axis between experimental and numerical results. The reproducibility of the results is excellent.
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