The Investigation of Turbine and Exhaust Interactions in Asymmetric Flows— Blade-Row Models Applied

2003 ◽  
Vol 125 (1) ◽  
pp. 121-127 ◽  
Author(s):  
J. J. Liu ◽  
T. P. Hynes
Keyword(s):  
Exhaust System ◽  
Numerical Approach ◽  
Flow Properties ◽  
Asymmetric Flow ◽  
Disk Model ◽  
Field Coupling ◽  
Actuator Disk ◽  
Blade Row ◽  
Sample Application ◽  
Asymmetric Flows

This paper describes the blade-row models applied to the asymmetric flow-field coupling between turbine and exhaust system. Numerical actuator disk is applied to represent a turbine blade row around the whole annulus and flow properties across the disk can jump to achieve required flow turning and entropy rise. The derivation of disk boundary conditions and the implementation in CFD solvers are described in detail. Validation of the actuator disk model and sample application of the present numerical approach are presented.

The Investigation of Turbine and Exhaust Interactions in Asymmetric Flows: Part 1 — Blade-Row Models Applied

2002 ◽  
Author(s):  
J. J. Liu ◽  
T. P. Hynes
Keyword(s):  
Exhaust System ◽  
Numerical Approach ◽  
Flow Properties ◽  
Asymmetric Flow ◽  
Field Coupling ◽  
Disc Model ◽  
Blade Row ◽  
Actuator Disc ◽  
Sample Application ◽  
Asymmetric Flows

Part 1 of this paper describes the blade-row models applied to the asymmetric flow field coupling between turbine and exhaust system. Numerical actuator is applied to represent a turbine blade row around whole annulus and flow properties across the disc can jump to achieve required flow turning and entropy rise. The derivation of disc boundary conditions and the implementation in CFD solvers are described in detail. Validation of the actuator disc model and sample application of the present numerical approach are presented.

The Simulation of Turbomachinery Blade Rows in Asymmetric Flow Using Actuator Disks

1997 ◽  
Vol 119 (4) ◽  
pp. 723-732 ◽  
Author(s):  
W. G. Joo ◽  
T. P. Hynes
Keyword(s):  
Supersonic Flow ◽  
Flow Field ◽  
Boundary Conditions ◽  
High Speed ◽  
Axial Position ◽  
Numerical Implementation ◽  
Asymmetric Flow ◽  
Actuator Disk ◽  
Blade Row ◽  
Flow Through

This paper describes the development of actuator disk models to simulate the asymmetric flow through high-speed low hub-to-tip ratio blade rows. The actuator disks represent boundaries between regions of the flow in which the flow field is solved by numerical computation. The appropriate boundary conditions and their numerical implementation are described, and particular attention is paid to the problem of simulating the effect of blade row blockage near choking conditions. Guidelines on choice of axial position of the disk are reported. In addition, semi-actuator disk models are briefly described and the limitations in the application of the model to supersonic flow are discussed.

scholarly journals Supersonic Stall Flutter of High-Speed Fans

1982 ◽  
Vol 104 (3) ◽  
pp. 675-682 ◽  
Author(s):  
J. J. Adamczyk ◽  
W. Stevans ◽  
R. Jutras
Keyword(s):  
Dynamic Response ◽  
Rotor Blade ◽  
High Speed ◽  
Aerodynamic Force ◽  
Rotor System ◽  
Flexural Mode ◽  
Disk Model ◽  
Actuator Disk ◽  
Blade Row ◽  
Flutter Boundary

An analytical model is developed for predicting the onset of supersonic stall bending flutter in axial-flow compressors. The analysis is based on a modified two-dimensional, compressible, unsteady actuator disk theory. It is applied to a rotor blade row by considering a cascade of airfoils whose geometry and dynamic response coincide with those of a rotor blade element at 85 percent of the span height (measured from the hub). The rotor blades are assumed to be unshrouded (i.e., free standing) and to vibrate in their first flexural mode. The effects of shock waves and flow separation are included in the model through quasisteady, empirical, rotor total-pressure-loss and deviation-angle correlations. The actuator disk model predicts the unsteady aerodynamic force acting on the cascade blading as a function of the steady flow field entering the cascade and the geometry and dynamic response of the cascade. Calculations show that the present model predicts the existence of a bending flutter mode at supersonic inlet Mach numbers. This flutter mode is suppressed by increasing the reduced frequency of the system or by reducing the steady-state aerodynamic loading on the cascade. The validity of the model for predicting flutter is demonstrated by correlating the measured flutter boundary of a high-speed fan stage with its predicted boundary. This correlation uses a level of damping for the blade row (i.e., the log decrement of the rotor system) that is estimated from the experimental flutter data. The predicted flutter boundary is shown to be in good agreement with the measured boundary. These results show that the model can be used to estimate the relative stability between operating points of a given rotor system. If, in addition, a measure of the mechanical damping of the rotor system is available, the model can also be used to estimate the absolute stability at an operating point.

The Design of a Large Diameter Axial Flow Fan for Air-Cooled Heat Exchanger Applications

2017 ◽  
Author(s):  
Michael B. Wilkinson ◽  
Johan van der Spuy ◽  
Theodor W. von Backström
Keyword(s):  
Flow Field ◽  
Large Diameter ◽  
Axial Flow ◽  
Pressure Rise ◽  
Design Procedure ◽  
Axial Flow Fan ◽  
Disk Model ◽  
Actuator Disk ◽  
Static Efficiency ◽  
Air Cooled Heat Exchanger

An axial flow fan design methodology is developed to design large diameter, low pressure rise, rotor-only fans for large air-cooled heat exchangers. The procedure aims to design highly efficient axial flow fans that perform well when subjected to off design conditions commonly encountered in air-cooled heat exchangers. The procedure makes use of several optimisation steps in order to achieve this. These steps include optimising the hub-tip ratio, vortex distribution, blading and aerofoil camber distributions in order to attain maximum total-to-static efficiency at the design point. In order to validate the design procedure a 24 ft, 8 bladed axial flow fan is designed to the specifications required for an air-cooled heat exchanger for a concentrated solar power (CSP) plant. The designed fan is numerically evaluated using both a modified version of the actuator disk model and a three dimensional periodic fan blade model. The results of these CFD simulations are used to evaluate the design procedure by comparing the fan performance characteristic data to the design specification and values calculated by the design code. The flow field directly down stream of the fan is also analysed in order to evaluate how closely the numerically predicted flow field matches the designed flow field, as well as determine whether the assumptions made in the design procedure are reasonable. The fan is found to meet the required pressure rise, however the fan total-to-static efficiency is found to be lower than estimated during the design process. The actuator disk model is found to under estimate the power consumption of the fan, however the actuator disk model does provide a reasonable estimate of the exit flow conditions as well as the total-to-static pressure characteristic of the fan.

scholarly journals An accurate semi-numerical approach for multilayer metasurfaces with near-field coupling

2021 ◽  
Author(s):  
xi Gao ◽  
Xiongbin Wu ◽  
Kexin Li ◽  
Jin-hui Shi ◽  
Guofu Wang ◽  
...  
Keyword(s):  
Near Field ◽  
Numerical Approach ◽  
Field Coupling

scholarly journals The CFD Investigation of Two Non-Aligned Turbines Using Actuator Disk Model and Overset Grids

2014 ◽  
Vol 524 ◽  
pp. 012144
Author(s):  
I O Sert ◽  
S C Cakmakcioglu ◽  
O Tugluk ◽  
N Sezer-Uzol
Keyword(s):  
Disk Model ◽  
Overset Grids ◽  
Actuator Disk

scholarly journals On Predicting the Phenomenon of Surface Flow Convergence in Wind Farms

2014 ◽  
Author(s):  
Suganthi Selvaraj ◽  
Anupam Sharma
Keyword(s):  
Wind Farm ◽  
Wind Farms ◽  
Surface Flow ◽  
Maximum Efficiency ◽  
Horizontal Axis Wind Turbine ◽  
Disk Model ◽  
Systematic Analysis ◽  
Actuator Disk ◽  
Momentum Theory ◽  
Flow Convergence

A systematic analysis of a single-rotor horizontal axis wind turbine aerodynamics is performed to obtain a realistic potential maximum efficiency. It is noted that by including the effects of swirl, viscosity and finite number of blades, the maximum aerodynamic efficiency of a HAWT is within a few percentage points of the efficiency of commercially-available turbines. The need for investigating windfarm (as a unit) aerodynamics is thus highlighted. An actuator disk model is developed and implemented in the OpenFOAM software suite. The model is validated against 1-D momentum theory, blade element momentum theory, as well as against experimental data. The validated actuator disk model is then used to investigate an interesting microscale meteorological phenomenon called “flow convergence” caused by an array of wind turbines. This phenomenon is believed to be caused by the drop of pressure in wind farms. Wind farm numerical simulations are conducted with various approximations to investigate and explain the flow convergence phenomenon.

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