Wake-Induced Unsteady Flows: Their Impact on Rotor Performance and Wake Rectification

1996 ◽  
Vol 118 (1) ◽  
pp. 88-95 ◽  
Author(s):  
J. J. Adamczyk ◽  
M. L. Celestina ◽  
Jen Ping Chen
Keyword(s):  
Viscous Flow ◽  
Three Dimensional ◽  
Unsteady Flows ◽  
Flow Simulation ◽  
Blade Row ◽  
Unsteady Simulation ◽  
Unsteady Viscous Flow ◽  
Inlet Conditions ◽  
The Impact ◽  
Rectification Process

The impact of wake-induced unsteady flows on blade row performance and the wake rectification process is examined by means of numerical simulation. The passage of a stator wake through a downstream rotor is first simulated using a three-dimensional unsteady viscous flow code. The results from this simulation are used to define two steady-state inlet conditions for a three-dimensional viscous flow simulation of a rotor operating in isolation. The results obtained from these numerical simulations are then compared to those obtained from the unsteady simulation both to quantify the impact of the wake-induced unsteady flow field on rotor performance and to identify the flow processes which impact wake rectification. Finally, the results from this comparison study are related to an existing model, which attempts to account for the impact of wake-induced unsteady flows on the performance of multistage turbomachinery.

scholarly journals Wake-Induced Unsteady Flows: Their Impact on Rotor Performance and Wake Rectification

1994 ◽  
Author(s):  
J. J. Adamczyk ◽  
M. L. Celestina ◽  
Jen Ping Chen
Keyword(s):  
Viscous Flow ◽  
Three Dimensional ◽  
Unsteady Flows ◽  
Flow Simulation ◽  
Blade Row ◽  
Unsteady Simulation ◽  
Unsteady Viscous Flow ◽  
Inlet Conditions ◽  
The Impact ◽  
Rectification Process

The impact of wake-induced unsteady flows on blade row performance and the wake rectification process is examined by means of numerical simulation. The passage of a stator wake through a downstream rotor is first simulated using a three dimensional unsteady viscous flow code. The results from this simulation are used to define two steady state inlet conditions for a three dimensional viscous flow simulation of a rotor operating in isolation. The results obtained from these numerical simulations are then compared to those obtained from the unsteady simulation both to quantify the impact of the wake-induced unsteady flow field on rotor performance and to identify the flow processes which impact wake rectification. Finally, the results from this comparison study are related to an existing model which attempts to account for the impact of wake-induced unsteady flows on the performance of multistage turbomachinery.

Assessment of Unsteady Flows in Turbines

1990 ◽  
Author(s):  
O. P. Sharma ◽  
G. F. Pickett ◽  
R. H. Ni
Keyword(s):  
Three Dimensional ◽  
Unsteady Flows ◽  
Flow Simulation ◽  
Experimental Investigations ◽  
Flow Parameters ◽  
Research Activities ◽  
Flow Features ◽  
Computational Fluid Dynamics Cfd ◽  
Turbine Design ◽  
The Impact

The impact of unsteady flows research activities on flow simulation methods used in the turbine design process are assessed. Results from experimental investigations which identify the impact of periodic unsteadiness on the time-averaged flows in turbines and results from numerical simulations obtained by using three-dimensional unsteady Computational Fluid Dynamics (CFD) codes indicate that some of the unsteady flow features can be fairly accurately predicted. Flow parameters that can be modeled with existing steady CFD codes are distinguished from those that require unsteady codes.

Assessment of Unsteady Flows in Turbines

1992 ◽  
Vol 114 (1) ◽  
pp. 79-90 ◽  
Author(s):  
O. P. Sharma ◽  
G. F. Pickett ◽  
R. H. Ni
Keyword(s):  
Unsteady Flow ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Experimental Investigations ◽  
Flow Parameters ◽  
Research Activities ◽  
Flow Features ◽  
Computational Fluid Dynamics Cfd ◽  
Turbine Design ◽  
The Impact

The impacts of unsteady flow research activities on flow simulation methods used in the turbine design process are assessed. Results from experimental investigations that identify the impact of periodic unsteadiness on the time-averaged flows in turbines and results from numerical simulations obtained by using three-dimensional unsteady Computational Fluid Dynamics (CFD) codes indicate that some of the unsteady flow features can be fairly accurately predicted. Flow parameters that can be modeled with existing steady CFD codes are distinguished from those that require unsteady codes.

scholarly journals A monolithic algorithm for the flow simulation of flexible flapping wings

2019 ◽  
Vol 11 ◽  
pp. 175682931984612 ◽  
Author(s):  
Tao Yang ◽  
Mingjun Wei ◽  
Kun Jia ◽  
James Chen
Keyword(s):  
Three Dimensional ◽  
Flow Simulation ◽  
Flapping Wings ◽  
Rigid Sphere ◽  
Two Dimensional ◽  
Unified Framework ◽  
Fluid Structure ◽  
A Cell ◽  
Three Dimensional Configuration ◽  
The Impact

It has been a challenge to simulate flexible flapping wings or other three-dimensional problems involving strong fluid–structure interactions. Solving a unified fluid–solid system in a monolithic manner improves both numerical stability and efficiency. The current algorithm considered a three-dimensional extension of an earlier work which formulated two-dimensional fluid–structure interaction monolithically under a unified framework for both fluids and solids. As the approach is extended from a two-dimensional to a three-dimensional configuration, a cell division technique and the associated projection process become necessary and are illustrated here. Two benchmark cases, a floppy viscoelastic particle in shear flow and a flow passing a rigid sphere, are simulated for validation. Finally, the three-dimensional monolithic algorithm is applied to study a micro-air vehicle with flexible flapping wings in a forward flight at different angles of attack. The simulation shows the impact from the angle of attack on wing deformation, wake vortex structures, and the overall aerodynamic performance.

Unsteady Three-Dimensional Viscous Flow Simulation of a Dragonfly Hovering

2004 ◽  
Author(s):  
Koji Isogai ◽  
Shun Fujishiro ◽  
Taku Saitoh ◽  
Manabu Yamamoto ◽  
Masahide Yamasaki ◽  
...  
Keyword(s):  
Viscous Flow ◽  
Three Dimensional ◽  
Flow Simulation

scholarly journals Design of Compressor Endwall Velocity Triangles

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Kiran Auchoybur ◽  
Robert J. Miller
Keyword(s):  
Dynamic Pressure ◽  
Three Dimensional ◽  
Flow Region ◽  
Degree Of Freedom ◽  
Diffusion Limit ◽  
Local Geometry ◽  
Operating Range ◽  
Blade Row ◽  
Inlet Conditions ◽  
Separation Size

The operating range of a compressor is usually limited by the rapid growth of three-dimensional (3D) separations in the endwall flow region. In contrast, the freestream region is not usually close to its diffusion limit and has little effect on overall range. In light of these two distinct flow regions, this paper considers how velocity triangles in the endwall region should be designed to give a more balanced spanwise failure across the span of a blade row. In the first part of this paper, the sensitivity of 3D separations in a single blade row to variations in realistic multistage inlet conditions and endwall geometry is investigated. It is shown that a blade's 3D separation size is largely controlled by the dynamic pressure within the incoming endwall “repeating stage” boundary layer and not the detailed local geometry within the blade row. In the second part of this 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 multistage environment to “tailor” the inlet profile into downstream blade rows, giving the designer a new extra degree-of-freedom. 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 ∼0.5% can be unlocked.

Quasi-Three-Dimensional Compressor Performance Simulation Using Streamline Curvature and Multi-Parallel Compressor Theory

2006 ◽  
Author(s):  
Ioannis Templalexis ◽  
Pericles Pilidis ◽  
Vassilios Pachidis ◽  
Petros Kotsiopoulos
Keyword(s):  
Total Pressure ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Radial Pressure ◽  
Simulation Code ◽  
Simulation Tools ◽  
Radial Distortion ◽  
Streamline Curvature ◽  
Compressor Performance ◽  
The Impact

Engine inlet distortion can severely affect compressor performance by causing the non-dimensional speed lines and surge line to shift. This paper discusses a highly integrated method for modelling engine inlet total pressure distortion and predicting compressor performance under these conditions. This study utilizes a three dimensional (3D), computational fluid dynamics (CFD) tool, based on vortex lattice theory, to simulate the development of distorted flow within the intake and to establish the boundary conditions at the compressor’s inlet face. The derived 3D pressure distributions at the intake outlet are subsequently decomposed into circumferential and radial pressure profiles. Circumferential and radial distortions are examined separately. The influence of the first profile type on compressor performance is assessed with the support of a multi-parallel compressor calculation procedure. The impact of the radial distortion profile is assessed by using a two-dimensional (2D) streamline curvature (SLC) software. Concerning the radial distortion, several distributions are examined along with various profile types. The circumferential total pressure distortion patterns addressed, are varied with respect to the spoiled sector extend and the absolute value in total pressure difference. More precisely, three spoiled sector angles of 60, 120 and 180 degrees are examined. This work demonstrates the applicability of the method by using a generic intake model fitted in front of a single stage compressor, as a case study. All the individual simulation tools, namely the intake flow simulation code, the SLC code and the multi-parallel compressor code, are briefly presented in this paper with more focus on the SLC software, which has not been published before. All simulation tools, used by this study, have been validated individually in the past against experimental data. Their combined operation however, as a unified simulation package, has not been validated yet and hence, numerical results presented in this study should be taken qualitative.

Vortex Transport and Blade Interactions in High Pressure Turbines

2003 ◽  
Author(s):  
V. S. P. Chaluvadi ◽  
A. I. Kalfas ◽  
H. P. Hodson
Keyword(s):  
High Pressure ◽  
Flow Field ◽  
Rotor Blade ◽  
Delta Wing ◽  
Classical Model ◽  
Three Dimensional ◽  
Axial Flow ◽  
Passage Vortex ◽  
Blade Row ◽  
The Impact

This paper presents a study of the three-dimensional flow field within the blade rows of a high-pressure axial flow steam turbine stage. Half-delta wings were fixed to a rotating hub to simulate an upstream rotor passage vortex. The flow field is investigated in a Low-Speed Research Turbine using pneumatic and hot-wire probes downstream of the blade row. The paper examines the impact of the delta wing vortex transport on the performance of the downstream blade row. Steady and unsteady numerical simulations were performed using structured 3D Navier-Stokes solver to further understand the flow field. The loss measurements at the exit of the stator blade showed an increase in stagnation pressure loss due to the delta wing vortex transport. The increase in loss was 21% of the datum stator loss, demonstrating the importance of this vortex interaction. The transport of the stator viscous flow through the rotor blade row is also described. The rotor exit flow was affected by the interaction between the enhanced stator passage vortex and the rotor blade row. Flow underturning near the hub and overturning towards the mid-span was observed, contrary to the classical model of overturning near the hub and underturning towards the mid-span. The unsteady numerical simulation results were further analysed to identify the entropy producing regions in the unsteady flow field.

Numerical Investigation of the Spear Valve Configuration on the Performance of Pelton and Turgo Turbine Injectors and Runners

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
D. Benzon ◽  
A. Židonis ◽  
A. Panagiotopoulos ◽  
G. A. Aggidis ◽  
J. S. Anagnostopoulos ◽  
...  
Keyword(s):  
Branch Pipe ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Hydraulic Efficiency ◽  
Impulse Turbine ◽  
Standard Design ◽  
Inlet Conditions ◽  
Improved Design ◽  
The Impact ◽  
Injector Design

This paper uses two modern commercial cfd software packages to compare the performance of a standard and improved impulse turbine injector developed in a previous study. The two injector designs are compared by simulating the two-dimensional (2D) axis-symmetric cases as well as full three-dimensional (3D) cases including the bend in the branch pipe and the guide vanes. The resulting jet profiles generated by these simulations are used to initialize the inlet conditions for a full Pelton and Turgo runner simulation at different operating conditions in order to assess the impact of the injector design on the performance and efficiency of a real impulse turbine. The results showed that the optimized injector design, with steeper nozzle and spear angles, not only attains higher efficiencies in the 2D and 3D injector simulations but also produces a jet which performs better than the standard design in both the Pelton and the Turgo runner simulations. The results show that the greatest improvement in the hydraulic efficiency occurs within the injector with the improved design, showing an increase in efficiency of 0.76% for the Turgo 3D injector and 0.44% for the Pelton 3D injector. The results also show that in the case of the 3D injector, the improved injector geometry produces a jet profile which induces better overall runner performance, giving a 0.5% increase in total hydraulic efficiency for the Pelton case and 0.7% for the Turgo case.

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