The Effect of Inlet Conditions on Turbine Endwall Loss

2021 ◽  
Author(s):  
John D. Coull ◽  
Christopher J. Clark
Keyword(s):  
Boundary Layers ◽  
Computational Study ◽  
Preliminary Design ◽  
Flow Conditions ◽  
Blade Row ◽  
Inlet Conditions ◽  
Axial Turbines ◽  
Design Optimum ◽  
Inlet Boundary Condition ◽  
General Method

Abstract There can be significant variation and uncertainty in the flow conditions entering a blade row. This paper explores how this variability can affect endwall loss in axial turbines. A computational study of three cascades with collinear inlet boundary layers is conducted. Endwall loss varies by more than a factor of 3 depending on the inlet conditions. This variation is caused by dissipation of Secondary Kinetic Energy (SKE). The results can be understood by observing that the inlet conditions predominantly control how secondary vorticity is distributed within the blade passage. Modestly-thick inlet boundary layers with high shape factor tend to displace vorticity towards the center of the passage. This displacement reduces vorticity cancellation, increasing secondary velocities and SKE. A general method is formulated to estimate SKE in preliminary design. Optimum aspect ratio is shown to depend on the inlet boundary condition. Strategies to reduce endwall loss and minimize sensitivity to inlet conditions are then highlighted.

A New Streamline Curvature Throughflow Method for Radial Turbomachinery

2008 ◽  
Author(s):  
Michael Casey ◽  
Chris Robinson
Keyword(s):  
Pressure Ratio ◽  
Compressible Fluids ◽  
Preliminary Design ◽  
Streamline Curvature ◽  
Trailing Edges ◽  
Blade Row ◽  
Curved Walls ◽  
Excellent Tool ◽  
Simple Numerical Model ◽  
General Method

This paper describes a newly developed streamline curvature throughflow method for the analysis of radial or mixed flow machines. The code includes curved walls, curved leading and trailing edges, and internal blade row calculating stations. A general method of specifying the empirical data provides separate treatment of blockage, losses, and deviation. Incompressible and compressible fluids are allowed, including real gases and supersonic relative flow in blade rows. The paper describes some new aspects of the code. In particular, a relatively simple numerical model for spanwise mixing is derived, the calculation method for prescribed pressure ratio in compressor bladed rows is described, and the method used to redistribute the flow across the span due to choking is given. Examples are given of the use and validation of the code for many types of radial turbomachinery and these show it is an excellent tool for preliminary design.

A New Streamline Curvature Throughflow Method for Radial Turbomachinery

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Michael Casey ◽  
Chris Robinson
Keyword(s):  
Pressure Ratio ◽  
Compressible Fluids ◽  
Preliminary Design ◽  
Streamline Curvature ◽  
Trailing Edges ◽  
Blade Row ◽  
Curved Walls ◽  
Excellent Tool ◽  
Simple Numerical Model ◽  
General Method

This paper describes a newly developed streamline curvature throughflow method for the analysis of radial or mixed flow machines. The code includes curved walls, curved leading and trailing edges, and internal blade row calculating stations. A general method of specifying the empirical data provides separate treatment of blockage, losses, and deviation. Incompressible and compressible fluids are allowed, including real gases and supersonic relative flow in blade rows. The paper describes some new aspects of the code. In particular, a relatively simple numerical model for spanwise mixing is derived; the calculation method for prescribed pressure ratio in compressor blade rows is described; and the method used to redistribute the flow across the span due to choking is given. Examples are given of the use and validation of the code for many types of radial turbomachinery, and these show that it is an excellent tool for preliminary design.

scholarly journals Turbocharger Axial Turbines for High Transient Response, Part 1: A Preliminary Design Methodology

2019 ◽  
Vol 9 (5) ◽  
pp. 838 ◽  
Author(s):  
Glen Walsh ◽  
Marco Berchiolli ◽  
Gregory Guarda ◽  
Apostolos Pesyridis
Keyword(s):  
Fluid Dynamics ◽  
Design Methodology ◽  
Design Space ◽  
Performance Model ◽  
Preliminary Design ◽  
Flow Conditions ◽  
Design Algorithm ◽  
Static Efficiency ◽  
Steady State Operation ◽  
Axial Turbines

This paper proposes a preliminary design algorithm for application of a turbocharger axial turbine, based on turbine thermodynamic analysis and the Ainley-Mathieson performance model that converges to the optimal design based on a set of input parameters and engine boundary conditions. A design space sweep was conducted, and a preliminary design was generated with a predicted total to static efficiency of 74.94%. CFD (computational fluid dynamics) was used to successfully validate the algorithm and show the preliminary design had a total to static efficiency of 73.98%. The design also produces the required power to support steady-state operation of the compressor in both free flow conditions and with a constrained pressure outlet.

Deviation in Axial Turbines at Subsonic Conditions

1999 ◽  
Author(s):  
A. M. T. Islam ◽  
S. A. Sjolander
Keyword(s):  
Pressure Difference ◽  
Optimization Problem ◽  
Functional Form ◽  
Subsonic Flow ◽  
Navier Stokes ◽  
Flow Conditions ◽  
Blade Loading ◽  
Blade Row ◽  
Axial Turbines ◽  
Empirical Coefficients

An improved correlation is presented for the deviation in axial turbines at subsonic flow conditions. Development of the correlation began with the assumption that the deviation is primarily determined by the blade loading (pressure difference) towards the trailing edge. The blade row parameters which influence this pressure difference are identified. A functional form for the correlation was then assumed and the unknown coefficients in the function were determined based on a database of known values of the deviation. This database includes in-house experimental results, estimates of deviation obtained from Navier-Stokes simulations, as well as cases from the literature for which sufficient geometric data are provided. The evaluation of the empirical coefficients of the correlation was treated as an optimization problem. The optimization was performed using a genetic algorithm which proved very effective and robust. The new deviation correlation appears to be significantly more successful than existing correlations.

Computational Study of the Risø-B1-18 Airfoil with a Hinged Flap Providing Variable Trailing Edge Geometry

2005 ◽  
Vol 29 (2) ◽  
pp. 89-113 ◽  
Author(s):  
Niels Troldborg
Keyword(s):  
Reynolds Number ◽  
Unsteady Flow ◽  
Computational Study ◽  
Turbine Blades ◽  
Aerodynamic Characteristics ◽  
Flow Conditions ◽  
Wind Turbine Blades ◽  
Trailing Edge ◽  
Edge Geometry ◽  
Fully Developed Turbulent Flow

A comprehensive computational study, in both steady and unsteady flow conditions, has been carried out to investigate the aerodynamic characteristics of the Risø-B1-18 airfoil equipped with variable trailing edge geometry as produced by a hinged flap. The function of such flaps should be to decrease fatigue-inducing oscillations on the blades. The computations were conducted using a 2D incompressible RANS solver with a k-w turbulence model under the assumption of a fully developed turbulent flow. The investigations were conducted at a Reynolds number of Re = 1.6 · 106. Calculations conducted on the baseline airfoil showed excellent agreement with measurements on the same airfoil with the same specified conditions. Furthermore, a more widespread comparison with an advanced potential theory code is presented. The influence of various key parameters, such as flap shape, flap size and oscillating frequencies, was investigated so that an optimum design can be suggested for application with wind turbine blades. It is concluded that a moderately curved flap with flap chord to airfoil curve ratio between 0.05 and 0.10 would be an optimum choice.

Mathematical Analysis for Off-Design Performance of Cryogenic Turboexpander

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Subrata K. Ghosh ◽  
R. K. Sahoo ◽  
Sunil K. Sarangi
Keyword(s):  
Pressure Ratio ◽  
Expansion Ratio ◽  
Flow Conditions ◽  
Flow Properties ◽  
Dimensional Solution ◽  
One Dimensional ◽  
Design Performance ◽  
Fluid Properties ◽  
The Mean ◽  
Inlet Conditions

A study has been conducted to determine the off-design performance of cryogenic turboexpander. A theoretical model to predict the losses in the components of the turboexpander along the fluid flow path has been developed. The model uses a one-dimensional solution of flow conditions through the turbine along the mean streamline. In this analysis, the changes of fluid and flow properties between different components of turboexpander have been considered. Overall, turbine geometry, pressure ratio, and mass flow rate are input information. The output includes performance and velocity diagram parameters for any number of given speeds over a range of turbine pressure ratio. The procedure allows any arbitrary combination of fluid species, inlet conditions, and expansion ratio since the fluid properties are properly taken care of in the relevant equations. The computational process is illustrated with an example.

Experimental and Computational Study of 2D Smooth Wall Turbulent Boundary Layers in Pressure Gradient

2022 ◽  
Author(s):  
Danny Fritsch ◽  
Vidya Vishwanathan ◽  
Christopher J. Roy ◽  
Todd Lowe ◽  
William J. Devenport ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Boundary Layers ◽  
Computational Study ◽  
Turbulent Boundary Layers ◽  
Smooth Wall

scholarly journals Design of Compressor Endwall Velocity Triangles

2016 ◽  
Author(s):  
Kiran Auchoybur ◽  
Robert J. Miller
Keyword(s):  
Flow Region ◽  
Degree Of Freedom ◽  
Diffusion Limit ◽  
Local Geometry ◽  
High Entropy ◽  
Operating Range ◽  
Leakage Flows ◽  
Multi Stage ◽  
Blade Row ◽  
Inlet Conditions

Near the endwalls of multi-stage compressor blade rows, there is a spanwise region of low momentum, high entropy fluid which develops due to the presence of annulus walls, leakage flows and corner separations. Off-design this region, known as the endwall flow region, often grows rapidly and in practice sets the compressor’s operating range. By contrast, over the operating range of the compressor, the freestream region of the flow is not usually close to its diffusion limit and has little effect on overall range. In light of these two distinct flow regions within a bladerow, this paper considers how velocity triangles in the endwall region should be designed to give a more balanced spanwise failure across the blade span. In the first part of the paper, the sensitivity of the operating flow range of a single blade row to variations in realistic multistage inlet conditions and endwall geometry is investigated. It is shown that the operating range of the blade row is largely controlled by the size and structure of the endwall ‘repeating stage’ inlet boundary layer and not the detailed local geometry within the blade row. In the second part of the paper the traditional design process is ‘flipped’. Instead of redesigning a blade’s endwall geometry to cope with a particular inlet profile into the blade row, the endwall region is redesigned in the multi-stage environment to ‘tailor’ the inlet profile into downstream blade rows. This is shown to allow an extra degree of freedom not usually open to the designer. This extra degree of freedom is exploited to balance freestream and endwall operating range, resulting in a compressor having an increased operating range of ∼20%. If this increased operating range is traded with reduced blade count, it is shown that a design efficiency improvement of Δη∼0.5% can be unlocked.

Integrated Motor/Propulsor Duct Optimization for Increased Vehicle and Propulsor Performance

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Stephen A. Huyer ◽  
Amanda Dropkin
Keyword(s):  
Fluid Dynamics ◽  
Computational Study ◽  
Mean Flow ◽  
Design Constraint ◽  
Propulsive Efficiency ◽  
Flow Acceleration ◽  
Blade Row ◽  
Total Vehicle ◽  
Stator Blade ◽  
Thrust And Torque

This paper presents a computational study to better understand the underlying fluid dynamics associated with various duct shapes and the resultant impact on both total vehicle drag and propulsor efficiency. A post-swirl propulsor configuration (downstream stator blade row) was selected with rotor and stator blade number kept constant. A generic undersea vehicle hull shape was chosen and the maximum shroud radius was required to lie within this body radius. A cylindrical rim-driven electric motor capable of generating a specific horsepower to achieve the design operational velocity required a set volume that established a design constraint limiting the shape of the duct. Individual duct shapes were designed to produce constant flow acceleration from upstream of the rotor blade row to downstream of the stator blade row. Ducts producing accelerating and decelerating flow were systematically examined. The axisymmetric Reynolds Averaged Navier–Stokes (RANS) version of fluent® was used to study the fluid dynamics associated with a range of accelerated and decelerated duct flow cases as well as provide the base total vehicle drag. For each given duct shape, the propeller blade design code, PBD 14.3, was used to generate an optimized rotor and stator. To provide fair comparisons, the maximum rotor radius was held constant with similar circulation distributions intended to generate equivalent amounts of thrust. Computations predicted that minimum vehicle drag was produced with a duct that produced zero mean flow acceleration. Ducted designs generating accelerating or decelerating flow increased drag. However, propulsive efficiency based exclusively on blade thrust and torque was significantly increased for accelerating flow through the duct and reduced for decelerating flow cases. Full 3D RANS flow simulations were then conducted for select test cases to quantify the specific blade, hull, and shroud forces and highlight the increased component drag produced by an operational propulsor, which reduced overall propulsive efficiency. From these results, a final optimized design was proposed.

Heat Transfer Investigation of an Aggressive Intermediate Turbine Duct: Part 1—Experimental Investigation

2010 ◽  
Author(s):  
Carlos Arroyo Osso ◽  
T. Gunnar Johansson ◽  
Fredrik Wallin
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Computational Study ◽  
Convective Heat Transfer Coefficient ◽  
Low Pressure ◽  
Flow Measurements ◽  
Pressure Losses ◽  
Turbofan Engines ◽  
Intermediate Turbine Duct ◽  
Inlet Conditions

In most designs of two-spool turbofan engines, intermediate turbine duct (ITD’s) are used to connect the high-pressure turbine (HPT) with the low-pressure turbine (LPT). Demands for more efficient engines with reduced emissions require more “aggressive ducts”, ducts which provide both a higher radial offset and a larger area ratio in the shortest possible length, while maintaining low pressure losses and avoiding non-uniformities in the outlet flow that might affect the performance of the downstream LPT. The work presented in this paper is part of a more comprehensive experimental and computational study of the flowfield and the heat transfer in an aggressive ITD. The main objectives of the study were to obtain an understanding of the mechanisms governing the heat transfer in ITD’s and to obtain high quality experimental data for the improvement of the CFD-based design tools. This paper consists of two parts. The first one, this one, presents and discusses the results of the experimental study. In the second part, a comparison between the experimental results and a numerical analysis is presented. The duct studied was a state-of-the-art “aggressive” design with nine thick non-turning structural struts. It was tested in a large-scale low-speed experimental facility with a single-stage HPT. In this paper measurements of the steady convective heat transfer coefficient (HTC) distribution on both endwalls and on the strut for the duct design inlet conditions are presented. The heat transfer measurement technique used is based on infrared-thermography. Part of the results of the flow measurements is also included.

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