Profile Loss Investigations With a S-CO2 Axial Turbine Aerofoil

2020 ◽  
Author(s):  
R. Senthil Kumaran ◽  
Dilipkumar B. Alone ◽  
Pramod Kumar
Keyword(s):  
Numerical Simulations ◽  
Brayton Cycle ◽  
Cfd Simulations ◽  
Fluid Medium ◽  
Real Gas ◽  
Linear Cascade ◽  
Profile Losses ◽  
Axial Turbines ◽  
Profile Loss ◽  
Flow Deflection

Abstract Axial turbines are being extensively designed for supercritical carbon-di-oxide (S-CO2) Brayton cycle power blocks. But very little information is available in the open literature on the aerodynamics of S-CO2 axial turbines, their aerofoils and loss mechanisms. The understanding of real gas behavior of S-CO2 inside a turbine is still very far from complete. Profile losses contribute to more than 50% of overall losses in a turbine. Hence, estimation of profile losses at the outset of the design process is very important. In the present study, the mean section aerofoil of the first stage of a 5 MWe Brayton cycle high temperature turbine is investigated for profile loss characteristics. The basic aerodynamic characteristics of the aerofoil in a linear cascade were initially studied using CFD simulations and cascade test experiments with air as the fluid medium. The aerofoil cascade is then subjected to numerical simulations with S-CO2 as the fluid medium. CFD simulations were carried out using a commercial RANS solver with SST k-ω turbulence model for closure. Air was modelled as ideal gas and S-CO2 was modelled as real gas with Refrigerant Gas Property tables generated over the appropriate pressure and temperature ranges using NIST Refprop database. Losses are also calculated using Craig and Cox loss model. Experiments were carried out by testing a linear cascade model comprising 12 two dimensional blades, in a high-speed cascade wind tunnel. Cascade tests were carried out over a range of exit Mach numbers and incidence angles with air as the working medium. Losses, flow deflection and blade loading were measured during the experiments. Scaling of the profile losses between air and S-CO2 fluid mediums were examined over a range of Mach numbers, Reynolds numbers and incidence angles. Detailed analysis of data generated from numerical simulations, experiments and loss model (mainly in the transonic regime) are discussed in this paper. Losses with S-CO2 was 1.5% lower than that of air while the flow deflection roughly remained the same.

Preliminary Aerodynamic Design of a S-CO2 Axial Turbine

2021 ◽  
Author(s):  
R. Senthil Kumaran ◽  
Dilipkumar B. Alone ◽  
Abdul Nassar ◽  
Pramod Kumar
Keyword(s):  
Mass Flow ◽  
Brayton Cycle ◽  
Cfd Simulations ◽  
Fluid Medium ◽  
Axial Turbine ◽  
Real Gas ◽  
Axial Turbines ◽  
Turbine Design ◽  
Turbomachinery Design ◽  
Line Design

Abstract Axial turbines are gaining prominence in supercritical carbon-di-oxide (S-CO2) Brayton cycle power blocks. S-CO2 Brayton cycle power systems designed for 10 MW and upwards will need axial turbines for efficient energy conversion and compact construction. The real gas behavior of S-CO2 and its rapid property variations with temperature presents a strong challenge for turbomachinery design. Applying gas and steam turbine philosophies directly to S-CO2 turbine could lead to erroneous designs. Very little information is available in the open literature on the design of S-CO2 axial turbines. In this paper, design of a 10 MW axial turbine for a simple recuperated Brayton cycle waste heat recovery system is presented. Three repeating stages with nominal stage loading coefficient of 2.3 and flow coefficient of 0.37 were designed. An axial turbine mean-line design method tuned to S-CO2 real gas fluid medium is discussed. 3D blade design was made suing commercial turbomachinery design software AxSTREAM. The turbine was designed for inlet temperature of 818.15 K, pressure ratio of 2.2, rotational speed of 12000 rpm and mass flow rate of 104.5 kg/s. 3D CFD simulations were carried out using the commercial RANS solver ANSYS CFX 2020 R2 with SST turbulence model for closure. S-CO2 was modelled as real gas with Refrigerant Gas Property tables generated over the appropriate pressure and temperature ranges using NIST Refprop database. CFD studies were carried out over a range of mass flow rates and speeds, covering the design and several off-design conditions. The performance maps generated using 3D CFD simulations of the turbine are presented. The geometrical parameters obtained with the mean-line design matched well with that of the 3D turbine design arrived using AxSTREAM. It was observed that the turbine produced 10 MW power at the design condition while passing the required mass flow. CFD studies also showed that the preliminary turbine design achieved a moderate total-to-total efficiency of 80 % at the design condition. The design has potential for further optimization to obtain improved efficiency and for reducing the number of stages from three to two.

Generation of the Equations for the Profile Losses Calculation in Blade Row of Axial Turbines in Design Analysis

2016 ◽  
Author(s):  
Oleg Baturin ◽  
Daria Kolmakova ◽  
Aleksey Gorshkov ◽  
Grigorii Popov
Keyword(s):  
Experimental Data ◽  
Statistical Analysis ◽  
Optimization Techniques ◽  
Distribution Law ◽  
Axial Turbine ◽  
Comparison Results ◽  
Profile Losses ◽  
Axial Turbines ◽  
New Equation ◽  
Profile Loss

The paper proposes a method for evaluating the reliability of models for estimating the energy losses in the blade rows of axial turbines, based on the statistical analysis of the experimental data deviation from the calculated. It was shown that these deviations are subject to the normal distribution law and can be described by mathematical expectations μΔξ and standard deviation σΔξ. The values of profile losses were calculated by five well-known models for 170 different axial turbines cascades, representing the diversity of turbines used in aircraft gas turbine engines. The findings were compared with experimental data. Comparison results were subjected to statistical analysis. It was found that the best model to describe the profile losses in axial turbines is model that has been developed in Central Institute of Aviation Motors (Russia). It allows the calculation of profile losses deviating from the actual values of losses by −8±84% with a probability of 95%. Taking into account the mentioned statistical criteria, a new equation was proposed based on the analysis of the profile losses nature and using mathematical optimization techniques. This equation makes possible to define the profile loss of axial turbine more accurate than the investigated models. It allows the calculation of profile loss values in the axial turbine that differ from the actual value by 10±61% with a probability of 95%. The proposed new equation takes into account more geometric and operational factors affecting the value of losses.

scholarly journals Effects of Periodic Wake Passing Upon Aerodynamic Loss of a Turbine Cascade: Part I — Measurements of Wake-Affected Cascade Loss by Use of a Pneumatic Probe

1999 ◽  
Author(s):  
Ken-ichi Funazaki ◽  
Nobuaki Tetsuka ◽  
Tadashi Tanuma
Keyword(s):  
Turbine Cascade ◽  
Flow Angle ◽  
Linear Cascade ◽  
Local Loss ◽  
Aerodynamic Loss ◽  
Free Stream Turbulence ◽  
Pressure Distributions ◽  
Wake Turbulence ◽  
Wake Passing ◽  
Profile Loss

This paper reports on an experimental investigation of aerodynamic loss of a low-speed linear turbine cascade which is subjected to periodic wakes shed from moving bars of the wake generator. In this case, parameters related to the wake, such as wake passing frequency (wake Strouhal number) or wake turbulence characteristics, are varied to see how these wake-related parameters affect the local loss distribution or mass-averaged loss coefficient of the turbine cascade. Free-stream turbulence intensity is changed by use of a turbulence grid. In Part I of this paper a focus is placed on the measurements by use of a pneumatic five-hole yawmeter, which provides time-averaged stagnation pressure distributions downstream of the moving bars as well as of the turbine cascade. Spanwise distributions of wake-affected exit flow angle are also measured. From this study it is found that the wake passing greatly affects not only the profile loss but secondary loss of the linear cascade. Noticeable change in exit flow angle is also identified.

Development of an Experimental Correlation for Transonic Turbine Flow

1987 ◽  
Vol 109 (2) ◽  
pp. 246-250 ◽  
Author(s):  
F. Martelli ◽  
A. Boretti
Keyword(s):  
Experimental Data ◽  
Operating Conditions ◽  
Geometric Parameters ◽  
Blade Profile ◽  
Profile Losses ◽  
Experimental Correlation ◽  
Transonic Turbine ◽  
The Relationship ◽  
Profile Loss ◽  
Correlation Procedure

Optimization of transonic turbine bladings over a broad range of operating conditions calls for better understanding of the relationship between blade profile loss and cascade geometric parameters. In fact, many of the experimental correlations published to date have failed to take into due consideration transonic effects, while others have considered far too few of the numerous geometric parameters affecting profile loss in transonic flows. Through examination of the experimental data gathered by some 20 authors regarding the effects of the most significant blading geometric parameters on profile losses, a loss correlation procedure has been developed. The procedure is especially advantageous in that it allows continuous updating as new experimental data become available.

A Study of the Three-Dimensional Unsteady Real-Gas Flows Within a Transonic ORC Turbine

2014 ◽  
Author(s):  
Andrew P. S. Wheeler ◽  
Jonathan Ong
Keyword(s):  
Three Dimensional ◽  
Organic Rankine Cycle ◽  
Leading Edge ◽  
Rankine Cycle ◽  
Gas Flows ◽  
Cfd Simulations ◽  
Significant Drop ◽  
Real Gas ◽  
Turbine Efficiency ◽  
Real Gas Effects

In this paper we investigate the three-dimensional unsteady real-gas flows which occur within Organic Rankine Cycle (ORC) turbines. A radial-inflow turbine stage operating with supersonic vane exit flows (M ≈ 1.4) is simulated using a RANS solver which includes real-gas effects. Steady CFD simulations show that small changes in the inducer shape can have a significant effect on turbine efficiency due to the development of supersonic flows in the rotor. Unsteady predictions show the same trends as the steady CFD, however a strong interaction between the vane trailing-edge shocks and rotor leading-edge leads to a significant drop in efficiency.

scholarly journals Influences of Pressure ratio and Fluid Temperature on overall Cooling Performances of Ribbed Channel with Film Holes

2021 ◽  
Vol 2087 (1) ◽  
pp. 012043
Author(s):  
Yi Li ◽  
Jianhua Wang ◽  
Xu Wang ◽  
Weilong Wu ◽  
Hang Su
Keyword(s):  
Numerical Simulations ◽  
Pressure Ratio ◽  
Fluid Temperature ◽  
Temperature Ratio ◽  
Cooling Effectiveness ◽  
Real Gas ◽  
Outlet Pressure ◽  
Ribbed Channel ◽  
Similar Temperature ◽  
Cooling Air

Abstract The previous experiments of overall cooling performances were most conducted using simplified models and under the similar temperature ratio of mainstream to cooling air with real gas turbine operations, and ambient outlet pressure. To discuss the reliability of this type of experimental data, this paper exhibits two series of numerical simulations. Using a real E3 blade as model, which has two-pass rib-roughened channel with inclined film holes, numerical simulations are carried out at the same temperature ratio and pressure ratio, but different fluid temperatures including mainstream and cooling air, and different outlet pressure. The numerical results reveal two important conclusions: 1) At the same outlet pressure, the overall cooling effectiveness on PS is not sensitive to the fluid temperatures, but on SS in the region between two rows of film holes, a higher fluid temperature corresponds to a higher cooling effectiveness. 2) At the same pressure ratio of inlet to outlet, the overall cooling effectiveness on PS and SS is not sensitive to the outlet pressure and fluid temperature.

Advances in axial turbine blade profile aerodynamics

2020 ◽  
pp. 095440622093631
Author(s):  
Jie Gao ◽  
Dongchen Huo ◽  
Guojie Wang ◽  
Guojun Ma
Keyword(s):  
Turbine Blade ◽  
Working Conditions ◽  
High Efficiency ◽  
Flow Characteristics ◽  
Blade Profile ◽  
Loss Mechanism ◽  
Design And Optimization ◽  
Profile Losses ◽  
Axial Turbines ◽  
Loss Control

The aerodynamic performance of axial turbines depends significantly on profile losses, secondary flow losses, and clearance gap losses of vanes and blades. In modern high-efficiency turbomachinery operating at various working conditions, profile losses are very important criteria for the development of vanes and blades, and turbine designers strive to minimize the losses, based on better understandings of flow and loss characteristics at various working conditions. This paper summarizes recent advances in the field of turbine blade profile aerodynamics, and covers: (1) flow and loss characteristics of blade profiles, (2) flow structure and loss mechanism for transonic blade profiles, (3) off-design performance, (4) flow control, (5) design and optimization, (6) engineering design considerations, and (7) research methods of blade profile aerodynamics. The emphasis is placed on flow characteristics and loss control methods, and present insights regarding the current research trends and the prospects for future developments.

Aerodynamic design of the high pressure and low pressure axial turbines for the improved coal-fired recompression SCO2 reheated Brayton cycle

Energy ◽  
2019 ◽  
Vol 179 ◽  
pp. 442-453 ◽  
Author(s):  
Wanlong Han ◽  
Yifan Zhang ◽  
Hongzhi Li ◽  
Mingyu Yao ◽  
Yueming Wang ◽  
...  
Keyword(s):  
High Pressure ◽  
Low Pressure ◽  
Brayton Cycle ◽  
Aerodynamic Design ◽  
Axial Turbines

scholarly journals Design of a Centrifugal Compressor Stage and a Radial-Inflow Turbine Stage for a Supercritical CO2 Recompression Brayton Cycle by Using 3D Inverse Design Method

2017 ◽  
Author(s):  
Jiangnan Zhang ◽  
Pedro Gomes ◽  
Mehrdad Zangeneh ◽  
Benjamin Choo
Keyword(s):  
Centrifugal Compressor ◽  
Supercritical Co2 ◽  
Design Method ◽  
Ideal Gas ◽  
Inverse Design ◽  
Brayton Cycle ◽  
Real Gas ◽  
Radial Inflow Turbine ◽  
Inverse Design Method ◽  
The Ideal

It is found that the ideal gas assumption is not proper for the design of turbomachinery blades using supercritical CO2 (S-CO2) as working fluid especially near the critical point. Therefore, the inverse design method which has been successfully applied to the ideal gas is extended to applications for the real gas by using a real gas property lookup table. A fast interpolation lookup approach is implemented which can be applied both in superheated and two-phase regimes. This method is applied to the design of a centrifugal compressor blade and a radial-inflow turbine blade for a S-CO2 recompression Brayton cycle. The stage aerodynamic performance (volute included) of the compressor and turbine is validated numerically by using the commercial CFD code ANSYS CFX R162. The structural integrity of the designs is also confirmed by using ANSYS Workbench Mechanical R162.

Numerical Investigation of Aerodynamic Radial and Axial Impeller Forces in a Turbocharger

2011 ◽  
Author(s):  
Henning Raetz ◽  
Jasper Kammeyer ◽  
Christoph K. Natkaniec ◽  
Joerg R. Seume
Keyword(s):  
Numerical Simulations ◽  
Numerical Investigation ◽  
Operating Conditions ◽  
Aerodynamic Forces ◽  
Cfd Simulations ◽  
Axial Forces ◽  
Ansys Cfx ◽  
Radial Turbines ◽  
Bearing Friction

Aerodynamic forces are a major cause of turbocharger bearing friction. Thus, numerical simulations with ANSYS CFX are performed for a turbocharger turbine and compressor in order to determine these forces. Today, in common turbocharger CFD simulations the influence of the impeller backside cavity and blow-by are usually neglected. As a consequence, the axial forces on the impeller cannot be correctly determined. In this study therefore, the impeller backside cavity and blow-by were taken into account. Additionally, the influence of different operating conditions as well as different turbine and compressor blow-by flows were investigated. Finally, the resulting aerodynamic impeller forces of a turbocharger were analysed and visualized. The results show some trends which agree with the impeller forces of larger radial turbines and compressors published in literature. However some turbocharger-specific differences are identified, e.g. the wide operation range of a turbocharger. The influences of blow-by are found to be small but not negligible.

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