Applied Sciences

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21 pages, 6974 KiB

Open AccessArticle

Development and Validation of Aerodynamic Measurement on a Horizontal Axis Wind Turbine in the Field

by Guangxing Wu, Lei Zhang and Ke Yang

Appl. Sci. 2019, 9(3), 482; https://doi.org/10.3390/app9030482 - 30 Jan 2019

Cited by 15 | Viewed by 5729

Aerodynamic measurement on horizontal axis wind turbines in the field is a challenging research topic and also an essential research method on the aerodynamic performance of blades in real atmospheric inflow conditions. However, the angle of attack is difficult to determine in the [...] Read more.

Aerodynamic measurement on horizontal axis wind turbines in the field is a challenging research topic and also an essential research method on the aerodynamic performance of blades in real atmospheric inflow conditions. However, the angle of attack is difficult to determine in the field due to the unsteadiness and unevenness of the inflow. To study the measuring and analyzing method of angle of attack in the field, a platform was developed based on a 100 kW wind turbine from the Institute of Engineering Thermophysics (IET) in China in this paper. Seven-hole probes were developed and installed at the leading edge to measure the inflow direction, static and total pressure at the near field. Two data reducing processes, sideslip angle correction, and induced velocity correction, were proposed to determine the effective angle of attack based on the inflow data measured by probes. The aerodynamic measurement platform was first validated by the comparison with wind tunnel results. Then some particular aerodynamic phenomenon in the field were discussed. As a result, the angle of attack varies quasi-periodically with the rotation of the rotor, which is caused by the yaw angle of the inflow. The variation of angle of attack induces dynamic response of a clockwise hysteresis loop in lift coefficient. The dynamic response is the main source of a dispersion of instantaneous lift coefficients with a standard deviation of 0.2. Full article

(This article belongs to the Special Issue Radial Turbomachinery Aerodynamics)

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20 pages, 2989 KiB

Open AccessArticle

Optimization of a Centrifugal Compressor Using the Design of Experiment Technique

by Mohammad Mojaddam and Keith R. Pullen

Appl. Sci. 2019, 9(2), 291; https://doi.org/10.3390/app9020291 - 15 Jan 2019

Cited by 35 | Viewed by 8366

Abstract

Centrifugal compressor performance is affected by many parameters, optimization of which can lead to superior designs. Recognizing the most important parameters affecting performance helps to reduce the optimization process cost. Of the compressor components, the impeller plays the most important role in compressor [...] Read more.

Centrifugal compressor performance is affected by many parameters, optimization of which can lead to superior designs. Recognizing the most important parameters affecting performance helps to reduce the optimization process cost. Of the compressor components, the impeller plays the most important role in compressor performance, hence the design parameters affecting this component were considered. A turbocharger centrifugal compressor with vaneless diffuser was studied and the parameters investigated included meridional geometry, rotor blade angle distribution and start location of the main blades and splitters. The diffuser shape was captured as part of the meridional geometry. Applying a novel approach to the problem, full factorial analysis was used to investigate the most effective parameters. The Response Surface Method was then implemented to construct the surrogate models and to recognize the best points over a design space created as based on the Box-Behnken methodology. The results highlighted the factors that affected impeller performance the most. Using the Design of Experiment technique, the model which optimized both efficiency and pressure ratio simultaneously delivered a design with 3% and 11% improvement in each respectively in comparison to the initial impeller at the design point. Importantly, this was not at the expense of sacrificing range, of critical concern in compressor design. Full article

(This article belongs to the Special Issue Radial Turbomachinery Aerodynamics)

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21 pages, 9304 KiB

Open AccessArticle

Multidisciplinary Design Optimization for a Centrifugal Compressor Based on Proper Orthogonal Decomposition and an Adaptive Sampling Method

by Lizhang Zhang, Dong Mi, Cheng Yan and Fangming Tang

Appl. Sci. 2018, 8(12), 2608; https://doi.org/10.3390/app8122608 - 13 Dec 2018

Cited by 11 | Viewed by 4078

Abstract

A centrifugal compressor is required to increase aerodynamic efficiency, ensure structural integrity, and reduce processing costs. This paper presents a dimension reduction technique based on proper orthogonal decomposition (POD) in combination with an adaptive sampling method to reduce computational costs. Design of experiment [...] Read more.

A centrifugal compressor is required to increase aerodynamic efficiency, ensure structural integrity, and reduce processing costs. This paper presents a dimension reduction technique based on proper orthogonal decomposition (POD) in combination with an adaptive sampling method to reduce computational costs. Design of experiment (DOE) is first used to choose initial sampling points. Then, parts of the sampling points are selected to format the snapshot matrix. Subsequently, the number of principal components to be retained is determined after POD analysis. An adaptive sampling point adding approach is used to increase new sampling points. The approach places more points around the regions of initial optimum designs by learning the information from previous data through POD analysis. Finally, the POD coefficients are selected to act as new design variables in the following multidisciplinary design optimization process. The method is first tested by three mathematical benchmark functions. The proposed method is then used to optimize a centrifugal compressor, of which the results are verified by tests. A normalized isentropic efficiency improvement of 3.7% and 3.0% in the maximum speed state and cruise state has been obtained after optimization. Additionally, the processing costs are reduced by about 30% owing to the number of blades reduced. Full article

(This article belongs to the Special Issue Radial Turbomachinery Aerodynamics)

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26 pages, 31898 KiB

Open AccessArticle

CFD Investigation of a High Head Francis Turbine at Speed No-Load Using Advanced URANS Models

by Jean Decaix, Vlad Hasmatuchi, Maximilian Titzschkau and Cécile Münch-Alligné

Appl. Sci. 2018, 8(12), 2505; https://doi.org/10.3390/app8122505 - 5 Dec 2018

Cited by 15 | Viewed by 4900

Abstract

Due to the integration of new renewable energies, the electrical grid undergoes instabilities. Hydroelectric power plants are key players for grid control thanks to pumped storage power plants. However, this objective requires extending the operating range of the machines and increasing the number [...] Read more.

Due to the integration of new renewable energies, the electrical grid undergoes instabilities. Hydroelectric power plants are key players for grid control thanks to pumped storage power plants. However, this objective requires extending the operating range of the machines and increasing the number of start-up, stand-by, and shut-down procedures, which reduces the lifespan of the machines. CFD based on standard URANS turbulence modeling is currently able to predict accurately the performances of the hydraulic turbines for operating points close to the Best Efficiency Point (BEP). However, far from the BEP, the standard URANS approach is less efficient to capture the dynamics of 3D flows. The current study focuses on a hydraulic turbine, which has been investigated at the BEP and at the Speed-No-Load (SNL) operating conditions. Several “advanced” URANS models such as the Scale-Adaptive Simulation (SAS) SST

k - ω

and the BSL- EARSM have been considered and compared with the SST

k - ω

model. The main conclusion of this study is that, at the SNL operating condition, the prediction of the topology and the dynamics of the flow on the suction side of the runner blade channels close to the trailing edge are influenced by the turbulence model. Full article

(This article belongs to the Special Issue Radial Turbomachinery Aerodynamics)

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14 pages, 3873 KiB

Open AccessArticle

Experimental Verification of the Dynamic Model of Turbine Blades Coupled by a Sealing Strip

by Chiara Gastaldi and Teresa M. Berruti

Appl. Sci. 2018, 8(11), 2174; https://doi.org/10.3390/app8112174 - 6 Nov 2018

Cited by 9 | Viewed by 3608

Abstract

This paper presents the experimental-numerical comparison of a bladed system with flexible strip dampers. The experimental results constitute, to the authors’ knowledge, the first published experimental evidence on strip dampers. They explore the in-phase and out-of-phase mode of vibration of two blades coupled [...] Read more.

This paper presents the experimental-numerical comparison of a bladed system with flexible strip dampers. The experimental results constitute, to the authors’ knowledge, the first published experimental evidence on strip dampers. They explore the in-phase and out-of-phase mode of vibration of two blades coupled by a strip damper. The great influence the mode of vibration has on the strip behaviour and consequent effect on the blades’ response is highlighted, analyzed and successfully simulated numerically. Experiments are made possible by a purposely developed loading system based on compressed air. This non-contact system enables the experimenter to apply a realistic value of contact pressure on the strip without adding spurious stiffness to the system or modifying the contact conditions. The availability of experimental data obtained by imposing realistic contact conditions constitutes a true added value. It is here shown how the full stick linear FRFs (Frequency Response Functions), typically used to predict the response in case of limited excitation on blades coupled by rigid dampers, do not offer significant results in the case of flexible strip dampers. Full article

(This article belongs to the Special Issue Radial Turbomachinery Aerodynamics)

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16 pages, 5070 KiB

Open AccessArticle

An Integrated Design and Optimization Approach for Radial Inflow Turbines—Part I: Automated Preliminary Design

by Qinghua Deng, Shuai Shao, Lei Fu, Haifeng Luan and Zhenping Feng

Appl. Sci. 2018, 8(11), 2038; https://doi.org/10.3390/app8112038 - 24 Oct 2018

Cited by 10 | Viewed by 3620

Abstract

An integrated design and optimization approach was developed for radial inflow turbines, which consists of two modules, an automated preliminary design module, and a flexible three-dimensional multidisciplinary optimization module. In this paper, the first module about the automated preliminary design approach was presented [...] Read more.

An integrated design and optimization approach was developed for radial inflow turbines, which consists of two modules, an automated preliminary design module, and a flexible three-dimensional multidisciplinary optimization module. In this paper, the first module about the automated preliminary design approach was presented in detail and validated by the experimental data. The approach employs a genetic algorithm to explore the design space defined by the loading coefficient, flow coefficient, and rotational speed. The aim is to obtain the best design scheme with high aerodynamic performance under specified constraints and to reduce the dependency on human experiences when designing a radial inflow turbine. The validation results show that the present approach is able to get the optimal design and alleviate the dependence on the designer’s expertise under specified constraints at the preliminary design stage. Furthermore, the optimization results indicate that using the present optimization approach the total-to-static efficiency of the optimized T-100 radial inflow turbine can be increased by 1.0% under design condition and the rotor weight can be decreased by 0.35 kg (26.7%) as compared with that of the original case. Full article

(This article belongs to the Special Issue Radial Turbomachinery Aerodynamics)

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19 pages, 8959 KiB

Open AccessArticle

An Integrated Design and Optimization Approach for Radial Inflow Turbines—Part II: Multidisciplinary Optimization Design

by Qinghua Deng, Shuai Shao, Lei Fu, Haifeng Luan and Zhenping Feng

Appl. Sci. 2018, 8(11), 2030; https://doi.org/10.3390/app8112030 - 23 Oct 2018

Cited by 14 | Viewed by 3267

Abstract

This paper proposes an integrated design and optimization approach for radial inflow turbines consisting of an automated preliminary design module and a flexible three-dimensional multidisciplinary optimization module. The latter was constructed by an evolution algorithm, a genetic algorithm-assisted self-learning artificial neural network and [...] Read more.

This paper proposes an integrated design and optimization approach for radial inflow turbines consisting of an automated preliminary design module and a flexible three-dimensional multidisciplinary optimization module. The latter was constructed by an evolution algorithm, a genetic algorithm-assisted self-learning artificial neural network and a dynamic sampling database. The 3-D multidisciplinary optimization approach was validated by the original T-100 turbine and the T-100re turbine obtained from the automated preliminary design approach, for maximizing the total-to-static efficiency and minimizing the rotor weight while keeping the mass flow rate constant and stress limitation satisfied. The validation results indicate that the total-to-static efficiency is 89.6%, increased by 1.3%, and the rotor weight is reduced by 0.14 kg (14.6%) based on the T-100re turbine, while the efficiency is 88.2%, increased by 2.2% and the weight is reduced by 0.49 kg (37.4%) based on the original T-100 turbine. Moreover, the T-100re turbine shows better performance at the preliminary design stage and conserves this advantage to the end, though both the aerodynamic performance of the T-100 and the T-100re turbine are improved after 3-D optimization. At the same time, it is implied that the preliminary design plays an essential role in the radial inflow turbine design process, and it is hard for only 3-D optimization to get a further performance improvement. Full article

(This article belongs to the Special Issue Radial Turbomachinery Aerodynamics)

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15 pages, 4411 KiB

Open AccessArticle

Radial Gradient Pressure Effects on Flow Behavior in a Dual Volute Turbocharger Turbine

by Azadeh Sajedin, Mohammad Hasan Shojaeefard and Abolfazl Khalkhali

Appl. Sci. 2018, 8(10), 1961; https://doi.org/10.3390/app8101961 - 17 Oct 2018

Cited by 3 | Viewed by 3181

Abstract

The pressure gradient in the dual volute radial turbocharger turbines is the primary source of the vortices’ formation in rotor passages. The effects of the upstream non-uniform flow conditions on the development of secondary flows are not well known. In this study, the [...] Read more.

The pressure gradient in the dual volute radial turbocharger turbines is the primary source of the vortices’ formation in rotor passages. The effects of the upstream non-uniform flow conditions on the development of secondary flows are not well known. In this study, the effect of highly skewed and non-uniform mass flow on the secondary vortices in different admission cases in a dual entry turbine was investigated using CFD modeling. The results agree well with the experiment, and show that increasing the inequality of the pressure between the entries leads to a reduction in the turbine’s performance. Some useful energy dissipates due to mixing the flows of the entries. Isolating the rotor sectors in the tongues region was applied with the purpose of limiting the mixing. Also, the vortices’ behavior in the rotor passages with different surface pressure ratios for the passage sides were investigated for both equal and partial admission. The surface pressure of the airfoil pressure side was more effective on the tip and trailing edge vortex than the suction side, while the leading-edge root vortex did not change by any variation in the surface pressure ratio. The vortices’ center location shifted with the pressure variation, and consequently, by decreasing the pressure level, the center of the tip vorticity turned to the upstream sections, and the leading-edge root vortex center moved closer to the pressure side. Full article

(This article belongs to the Special Issue Radial Turbomachinery Aerodynamics)

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23 pages, 8581 KiB

Open AccessArticle

A Dynamic Approach for Faster Performance Measurements on Hydraulic Turbomachinery Model Testing

by Vlad Hasmatuchi, Alin Ilie Bosioc, Sébastien Luisier and Cécile Münch-Alligné

Appl. Sci. 2018, 8(9), 1426; https://doi.org/10.3390/app8091426 - 21 Aug 2018

Cited by 5 | Viewed by 4017

Abstract

During the design and optimization of hydraulic turbomachines, the experimental evaluation of hydraulic performances beyond the best efficiency point and for off-design conditions remains essential to validate the simulation process and to finalize the development. In this context, an alternative faster method to [...] Read more.

During the design and optimization of hydraulic turbomachines, the experimental evaluation of hydraulic performances beyond the best efficiency point and for off-design conditions remains essential to validate the simulation process and to finalize the development. In this context, an alternative faster method to measure the efficiency of hydraulic turbomachines using a dynamic approach has been investigated. The so-called “sliding-gate” dynamic measurement method has been adapted and implemented on the hydraulic test rig of the HES-SO Valais//Wallis, Sion, Switzerland. This alternative approach, particularly gainful for small-hydro for which the investment devoted to development is limited, has been successfully assessed on two cases for drinking water networks energy recovery. A 2.65 kW double-regulated laboratory prototype of a tubular axial micro-turbine with two independent variable speed counter-rotating runners and a 11 kW multi-stage centrifugal pump-as-turbine (PAT) with variable speed have been selected. The hydraulic efficiency results obtained by dynamic measurements are compared to the ones obtained by the classical steady point-by-point method. This dynamic method, suitable not only for hydraulic machinery, allows: (i) reducing significantly (up to 10×) the time necessary to draw the complete efficiency characteristics of a hydraulic machine; (ii) rapidly detecting the hydrodynamic instabilities within the operating range of the machine. Full article

(This article belongs to the Special Issue Radial Turbomachinery Aerodynamics)

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Graphical abstract

22 pages, 9478 KiB

Open AccessArticle

Analysis and Improvement of a Two-Stage Centrifugal Compressor Used in an MW-Level Gas Turbine

by Wei Zhu, Xiao-Dong Ren, Xue-Song Li and Chun-Wei Gu

Appl. Sci. 2018, 8(8), 1347; https://doi.org/10.3390/app8081347 - 10 Aug 2018

Cited by 11 | Viewed by 9042

Abstract

The performance of a low/high-pressure-stage centrifugal compressor in a land-use MW-level gas turbine with a pressure ratio of approximately 11 is analyzed and optimized with a 1D aerodynamic design and modeling optimization system. 1D optimization results indicate that the diameter ratio of the [...] Read more.

The performance of a low/high-pressure-stage centrifugal compressor in a land-use MW-level gas turbine with a pressure ratio of approximately 11 is analyzed and optimized with a 1D aerodynamic design and modeling optimization system. 1D optimization results indicate that the diameter ratio of the low-pressure-stage centrifugal compressor with a vane-less diffuser, and the divergent angle of the high-pressure-stage centrifugal compressor with a vaned diffuser, are extremely large and result in low efficiency. Through modeling design and optimization system analysis, a tandem vaned diffuser is used in the low-pressure stage, and a tandem vaned diffuser with splitter vanes is adopted in the high-pressure stage. Computational fluid dynamics (CFD) results show that the pressure ratio and efficiency of the optimized low/high-pressure-stage centrifugal compressor are significantly improved. Coupling calculations of the low/high-pressure stage of the original and optimized designs are conducted based on the results of MW-level gas turbine cycles. CFD results show that the pressure ratio and efficiency of the optimized two-stage centrifugal compressor increase by approximately 8% and 4%, respectively, under three typical load conditions of 100%, 90%, and 60%. Full article

(This article belongs to the Special Issue Radial Turbomachinery Aerodynamics)

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16 pages, 5319 KiB

Open AccessArticle

Research on the Simplified Design of a Centrifugal Compressor Impeller Based on Meridional Plane Modification

by Hong Xie, Moru Song, XiaoLan Liu, Bo Yang and Chuangang Gu

Appl. Sci. 2018, 8(8), 1339; https://doi.org/10.3390/app8081339 - 10 Aug 2018

Cited by 12 | Viewed by 4647

Abstract

This study mainly focuses on investigating the influence of meridional contour of a steam centrifugal compressor on aerodynamic performance. An optimal design method is put forwards, in which the hub-line on the meridional plane is modified and optimized. Based on the data from [...] Read more.

This study mainly focuses on investigating the influence of meridional contour of a steam centrifugal compressor on aerodynamic performance. An optimal design method is put forwards, in which the hub-line on the meridional plane is modified and optimized. Based on the data from numerical simulation, aerodynamic characteristics are compared in detail among a prototype and three modified impellers. It is shown that stall margin of the optimized impeller can be enlarged by approximately 50%, though at design point efficiency and pressure ratio is decreased a little bit. Under the working conditions with low flow rate, the optimized impeller exhibits the best performance compared with the prototype and two other impellers. Furthermore, numerical result is validated by the experiment and is matched the measure data very well. Full article

(This article belongs to the Special Issue Radial Turbomachinery Aerodynamics)

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