scholarly journals Numerical Simulation of the Performance of a Twin Scroll Radial Turbine at Different Operating Conditions

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Carlo Cravero ◽  
Davide De Domenico ◽  
Andrea Ottonello
Keyword(s):  
Operating Conditions ◽  
Inlet Section ◽  
Flow Distortion ◽  
Experimental Database ◽  
Design And Optimization ◽  
Radial Turbine ◽  
Ansys Cfx ◽  
Wide Range ◽  
Partial Admission ◽  
Turbine Design

Twin scroll radial turbines are increasingly used for turbocharging applications, to take advantage of the pulsating exhaust gases. In spite of its relevance in turbocharging techniques, scientific literature about CFD applied to twin scroll turbines is limited, especially in case of partial admission. In the present paper a CFD complete model of a twin scroll radial turbine is developed in order to give a contribution to literature in understanding the capabilities of current industrial CFD approaches applied to these difficult cases and to develop performance index that can be used for turbine design optimization purposes. The flow solution is obtained by means of ANSYS CFX ® in a wide range of operating conditions in full and partial admission cases. The total-to-static efficiency and the mass flow parameter (MFP) have been calculated and compared with the experimental database in order to validate the numerical model. The purpose of the developed procedure is also to generate a database for twin scroll turbines useful for future applications. A comparison between performances obtained in different admission conditions was performed. In particular the analysis focused on the characterization of the flow at volute outlet/rotor inlet section. A flow distortion index at rotor inlet was introduced to correlate the turbine performance and the flow nonuniformities generated by the volute. Finally the influence of the backside cavity on the performance parameters is also discussed. The introduction of these new nonuniformity indices is proposed for volute design and optimization procedures.

Performance Characterization of a Twin Scroll Volute for Turbocharging Applications

2018 ◽  
Author(s):  
Carlo Cravero ◽  
Mario La Rocca ◽  
Andrea Ottonello
Keyword(s):  
Experimental Data ◽  
Scientific Literature ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Automatic Design ◽  
Cfd Model ◽  
Radial Turbine ◽  
Wide Range ◽  
Partial Admission

The use of twin scroll volutes in radial turbine for turbocharging applications has several advantages over single passage volute related to the engine matching and to the overall compactness. Twin scroll volutes are of increasing interest in power unit development but the open scientific literature on their performance and modelling is still quite limited. In the present work the performance of a twin scroll volute for a turbocharger radial turbine are investigated in some detail in a wide range of operating conditions at both full and partial admission. A CFD model for the volute have been developed and preliminary validated against experimental data available for the radial turbine. Then the numerical model has been used to generate the database of solutions that have been investigated and used to extract the performance. Different parameters and indices are introduced to describe the volute aerodynamic performance in the wide range of operating conditions chosen. The above parameters can be used for volute development or matching with a given rotor or efficiently implemented in automatic design optimization strategies.

Investigation on the Degree of Reaction in Twin Scroll Radial Turbines at Different Operating Conditions for Turbocharging Applications

2019 ◽  
Author(s):  
Carlo Cravero ◽  
Davide De Domenico ◽  
Andrea Ottonello
Keyword(s):  
High Performance ◽  
Mean Value ◽  
Operating Conditions ◽  
Axial Thrust ◽  
Degree Of Reaction ◽  
Radial Turbine ◽  
Wide Range ◽  
Partial Admission ◽  
Rotor Losses ◽  
Radial Turbines

Abstract Frequently in turbocharging radial turbine studies, some assumptions have to be done in order to make 1D matching calculations as easy as possible and to develop simulation approaches that can be useful for different purposes, like axial thrust prediction. One of these assumptions concerns the degree of reaction, which is often considered constant and equal to the value 0.5. In standard radial turbines design the velocity triangles are set by the target to keep a mean degree of reaction of 50%, in order to obtain low rotor losses and to minimize the exit swirl to get lower losses in the exhaust diffuser. From the experience gained on radial turbines operating in a wide range of conditions, it is evident that: the degree of reaction presents large variations along a given isospeed (especially at low rotational speed) and the mean value is far from 0.5 (particularly true in high performance applications). In the present work a method for the representation of the degree of reaction for radial turbine is suggested. The approach has been developed onto a twin scroll radial turbine for turbocharging, considering a large dataset of operating conditions (at both equal and partial admission). The discussion and the method suggested are based on a rich database from experimental data and numerical simulations developed by the authors on the 3D configuration of the turbines under investigation.

Axial Turbine Design for a Twin-Turbine Heavy-Duty Turbocharger Concept

2018 ◽  
Author(s):  
Nicholas Anton ◽  
Magnus Genrup ◽  
Carl Fredriksson ◽  
Per-Inge Larsson ◽  
Anders Christiansen-Erlandsson
Keyword(s):  
Engine Performance ◽  
Operating Conditions ◽  
Single Stage ◽  
Flow Coefficient ◽  
Speed Ratio ◽  
Heavy Duty ◽  
Turbine Stage ◽  
Axial Turbine ◽  
Radial Turbine ◽  
Turbine Design

In the process of evaluating a parallel twin-turbine pulse-turbocharged concept, the results considering the turbine operation clearly pointed towards an axial type of turbine. The radial turbine design first analyzed was seen to suffer from sub-optimum values of flow coefficient, stage loading and blade-speed-ratio. Modifying the radial turbine by both assessing the influence of “trim” and inlet tip diameter all concluded that this type of turbine is limited for the concept. Mainly, the turbine stage was experiencing high values of flow coefficient, requiring a more high flowing type of turbine. Therefore, an axial turbine stage could be feasible as this type of turbine can handle significantly higher flow rates very efficiently. Also, the design spectrum is broader as the shape of the turbine blades is not restricted by a radially fibred geometry as in the radial turbine case. In this paper, a single stage axial turbine design is presented. As most turbocharger concepts for automotive and heavy-duty applications are dominated by radial turbines, the axial turbine is an interesting option to be evaluated for pulse-charged concepts. Values of crank-angle-resolved turbine and flow parameters from engine simulations are used as input to the design and subsequent analysis. The data provides a valuable insight into the fluctuating turbine operating conditions and is a necessity for matching a pulse-turbocharged system. Starting on a 1D-basis, the design process is followed through, resulting in a fully defined 3D-geometry. The 3D-design is evaluated both with respect to FEA and CFD as to confirm high performance and durability. Turbine maps were used as input to the engine simulation in order to assess this design with respect to “on-engine” conditions and to engine performance. The axial design shows clear advantages with regards to turbine parameters, efficiency and tip speed levels compared to a reference radial design. Improvement in turbine efficiency enhanced the engine performance significantly. The study concludes that the proposed single stage axial turbine stage design is viable for a pulse-turbocharged six-cylinder heavy-duty engine. Taking into account both turbine performance and durability aspects, validation in engine simulations, a highly efficient engine with a practical and realizable turbocharger concept resulted.

scholarly journals Design and Testing of a 10KW Steam Turbine for Steam Turbochargers

1985 ◽  
Author(s):  
M. Rautenberg ◽  
M. Malobabic ◽  
A. Mobarak ◽  
M. Abdel Kader
Keyword(s):  
Waste Heat ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Exhaust Gas ◽  
Test Rig ◽  
Pelton Turbine ◽  
Partial Admission ◽  
Turbine Design ◽  
Design And Testing

A Clausius-Rankine-cycle has been proposed to recover waste heat from a piston engine. This waste heat is then used to supercharge the cylinders by means of a steam turbocharger. The advantage of using this steam turbocharger system is to avoid the losses due to the engine back pressure which accompany the use of the conventional exhaust gas turbocharger. The mass flow rate of turbines for steam turbochargers in the range from 1 to 10 kW is about 0.03 to 0.08 kg/s. This implies a special turbine design, characterised by partial admission and supersonic flow, which unfortunately leads to low turbine efficiencies. A small Pelton turbine for steam has been designed and produced. The turbine is connected to the radial compressor of a conventional exhaust gas turbocharger which works, in this case, as a brake to dissipate the generated turbine power. A special test rig has been built to carry out the experimental investigations on the proposed Pelton turbine. The test rig is supplied with superheated steam from the University’s power plant. Two different rotors for this Pelton turbine have been tested under the same operating conditions (rotor 2 see Fig. 1). Some experimental test results of a special Pelton turbine are presented and discussed in this report.

Aerodynamic Damping Analysis for Radial Turbine Featuring a Multi-Channel Casing Design

2020 ◽  
Author(s):  
Ahmed Farid Hassan ◽  
Tobias Müller ◽  
Markus Schatz ◽  
Damian M. Vogt
Keyword(s):  
Damping Ratio ◽  
Full Model ◽  
Aerodynamic Damping ◽  
Radial Turbine ◽  
Damping Behavior ◽  
Ansys Cfx ◽  
Partial Admission ◽  
Time Marching ◽  
Opening And Closing ◽  
Spiral Casing

Abstract Radial turbine featuring a Multi-channel Casing (MC) is a new design under investigation for enhancing the turbine controllability. The idea behind this new design is to replace the traditional spiral casing with a MC, which allows controlling the mass flow by means of opening and closing control valves in each channel. The arrangement of the closed and opened channel is called the admission configuration, while the ratio between the counts of the open channels to the total number of channels is called the admission percentage. Among several aspects, when applying different admission configurations, the aerodynamic damping during resonant excitation is considered during the design of the turbine. The present study aims at investigating the effect of different MC admission configurations on the aerodynamic damping as an extension to an aerodynamic forcing study, which already assessed the different forcing patterns associated with these different admission configurations. Due to the asymmetry of the flow in circumferential direction resulting from the different partial admission configurations, the computational model is solved as full 3D time-marching, unsteady flow using ANSYS CFX in a one-way fluid-structure analysis. Two different modeling approaches have been considered in this study to investigate their capability of predicting the damping ratio for different MC admission configurations: a) the conventional isolated rotor approach and b) a full model consisting of the rotor and its casing. The results show that the casing affects the aerodynamic damping behavior, which can only be captured by the full model. Furthermore, the damping ratios for all different admission configurations have been calculated using the full stage model.

Numerical Optimization and Manufacturing of the Impeller of a Centrifugal Compressor by Variation of Splitter Blades

2016 ◽  
Author(s):  
S. Abolfazl Moussavi Torshizi ◽  
Ali Hajilouy Benisi ◽  
Mohammad Durali
Keyword(s):  
Operating Conditions ◽  
Structural Defects ◽  
Cnc Machine ◽  
Centrifugal Compressors ◽  
Design And Optimization ◽  
Optimization Study ◽  
Wide Range ◽  
Destructive Analysis ◽  
Compressor Performance ◽  
Non Destructive

Design and optimization of centrifugal compressors, based on main blades configuration of impeller have been vastly discussed in open literature, but less researches have addressed splitters. In this research, the impeller of a commercial turbocharger compressor is investigated. Here, profiles of main blades are not changed while the effect of changing the configuration of splitters is studied. An optimization study is performed to find the best configuration using genetic algorithm over a complete operating curve of the compressor. CFD codes with experimental support are used to predict the compressor performance. Quantumetric tests beside destructive analysis of two impellers are implemented for material identification and selection which is necessary for manufacturing. After taking into account structural considerations and approving the safety by numerical simulation, the new impeller is manufactured using 5 axis CNC machine. Non destructive tests are performed for identification of any structural defects. The new impeller is then mounted on a turbocharger shaft and tested experimentally in a wide range of operating conditions, which leads to a design having 2.3% improvement in efficiency. This is an important achievement in all applications of centrifugal compressors, especially in turbochargers.

scholarly journals Experimental, numerical and theoretical investigations of Tesla turbines

2019 ◽  
Vol 113 ◽  
pp. 03003
Author(s):  
Stefan Klingl ◽  
Stefan Lecheler ◽  
Michael Pfitzner
Keyword(s):  
Flow Model ◽  
Turbine Rotor ◽  
Operating Conditions ◽  
Design And Optimization ◽  
Optimal Power ◽  
Theoretical Investigations ◽  
Cost Efficient ◽  
Optimal Efficiency ◽  
Turbine Design ◽  
Gap Width

We use analytical, numerical and experimental methods to characterize the laminar flow inside a Tesla turbine rotor gap. A comparison based on one particular set of operating conditions mutually validates the three approaches. The simplicity of the analytical flow model allows for a cost efficient optimization of the underlying turbine parameters. Performance charts exhibit general trends and serve as a guide for preliminary turbine design and optimization. In terms of the ratio of half the gap width to inlet radius and the ratio of outletto inlet radius, the designer of a tesla turbine has to find a compromise between optimal efficiency and optimal power output.

A New Model for Predicting Flow Boiling Heat Transfer Coefficients in Horizontal Microfin Tubes

2016 ◽  
Author(s):  
Reem Merchant ◽  
Sunil Mehendale
Keyword(s):  
Heat Transfer ◽  
Flow Boiling ◽  
Operating Conditions ◽  
Transfer Coefficients ◽  
Experimental Database ◽  
New Model ◽  
Heat Transfer Coefficients ◽  
New Correlation ◽  
Wide Range ◽  
Microfin Tubes

The objective of the current work is to present a new correlation for predicting heat transfer coefficients (HTCs) for flow boiling in horizontal microfin tubes. Correlations to predict HTCs have been proposed by numerous authors such as Yu et al., Thome et al., Cavallini et al., Yun et al., Chamra and Mago, Wu et al., and other researchers. The correlations proposed are semi-empirical due to the difficulties associated with modeling the physics of flow boiling in microfin tubes. The above correlations are based on smooth tube flow boiling correlations which are modified to capture the effect of the inner grooves in the microfin tubes on the boiling process. In a previous work, it has been demonstrated that no single correlation can reasonably predict the flow boiling HTCs over a wide range of operating conditions and tube geometric parameters (Merchant and Mehendale). A new model has been proposed and validated using an experimental database of 1576 points from published literature. For the full dataset, the new correlation has X30% of 67.3%, compared to Cavallini et al. and Wu et al. with X30% of 44.2% and 40.6% respectively. The performance of the new model for tube diameters less than and greater than 5 mm has also been discussed for halogenated refrigerants and CO2.

Pre-Rotation Wind Turbine Design and Optimization for Aircraft Landing Gear

2017 ◽  
Vol 23 ◽  
pp. 88-103 ◽  
Author(s):  
Abdurrhman A. Alroqi ◽  
Wei Ji Wang
Keyword(s):  
Wind Turbine ◽  
Wind Power ◽  
Wind Turbines ◽  
Rotational Speed ◽  
Landing Gear ◽  
Design And Optimization ◽  
Aircraft Landing ◽  
Ansys Cfx ◽  
Aircraft Landing Gear ◽  
Turbine Design

Many patents have suggested that spinning aircraft wheels before landing could eliminate tyre smoke at touchdown. Most patents suggest using available wind power to rotate the wheel with wind turbines. In this paper, ANSYS CFX has been employed to simulate different wind turbines spinning a heavy aircraft wheel at approach. The aim of this research is to check the possibility of using wind power for this purpose and to optimize the wind turbine in a size acceptable in the field of aviation, in order to reach the target rotational speed.

scholarly journals Turbine Design and Optimization for a Supercritical CO2 Cycle Using a Multifaceted Approach Based on Deep Neural Network

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7807
Author(s):  
Muhammad Saeed ◽  
Abdallah S. Berrouk ◽  
Burhani M. Burhani ◽  
Ahmed M. Alatyar ◽  
Yasser F. Al Wahedi
Keyword(s):  
Neural Network ◽  
Deep Neural Network ◽  
Design Parameters ◽  
Speed Ratio ◽  
Inlet Flow ◽  
Flow Angle ◽  
Multifaceted Approach ◽  
Design And Optimization ◽  
Radial Turbine ◽  
Turbine Design

Turbine as a key power unit is vital to the novel supercritical carbon dioxide cycle (sCO2-BC). At the same time, the turbine design and optimization process for the sCO2-BC is complicated, and its relevant investigations are still absent in the literature due to the behavior of supercritical fluid in the vicinity of the critical point. In this regard, the current study entails a multifaceted approach for designing and optimizing a radial turbine system for an 8 MW sCO2 power cycle. Initially, a base design of the turbine is calculated utilizing an in-house radial turbine design and analysis code (RTDC), where sharp variations in the properties of CO2 are implemented by coupling the code with NIST’s Refprop. Later, 600 variants of the base geometry of the turbine are constructed by changing the selected turbine design geometric parameters, i.e., shroud ratio (rs4r3), hub ratio (rs4r3), speed ratio (νs) and inlet flow angle (α3) and are investigated numerically through 3D-RANS simulations. The generated CFD data is then used to train a deep neural network (DNN). Finally, the trained DNN model is employed as a fitting function in the multi-objective genetic algorithm (MOGA) to explore the optimized design parameters for the turbine’s rotor geometry. Moreover, the off-design performance of the optimized turbine geometry is computed and reported in the current study. Results suggest that the employed multifaceted approach reduces computational time and resources significantly and is required to completely understand the effects of various turbine design parameters on its performance and sizing. It is found that sCO2-turbine performance parameters are most sensitive to the design parameter speed ratio (νs), followed by inlet flow angle (α3), and are least receptive to shroud ratio (rs4r3). The proposed turbine design methodology based on the machine learning algorithm is effective and substantially reduces the computational cost of the design and optimization phase and can be beneficial to achieve realistic and efficient design to the turbine for sCO2-BC.

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