Experimental Investigation on Aerodynamic Behavior of a Compressor Cascade in Droplet Laden Flow

2013 ◽  
Author(s):  
Birger Ober ◽  
Franz Joos
Keyword(s):  
Experimental Investigation ◽  
Water Droplet ◽  
Gas Turbines ◽  
Renewable Energy Sources ◽  
Water Injection ◽  
Density Ratio ◽  
Experimental Investigations ◽  
Compressor Cascade ◽  
Discharge Flow ◽  
Air Compressor

The possibility to augment the power output of gas turbines by the use of water injection becomes more and more attractive in recent years as unsteadily available renewable energy sources become more present and the need of reserve power rises. Depending on the installed system, water injection may result in a two phase flow inside the compressor. The water droplet laden compressor flow promises benefits in efficiency and to some extent in performance and stability. The thermodynamic aspect has been thoroughly investigated as summarized by Eisfeld [1]. A promising approach is the stabilizing influence on highly stressed airfoils as experimentally investigated by Eisfeld and Joos [2] who conducted first systematic experimental investigations but were limited in the range of incidence angles. Multiple numerical investigations have been undertaken by different research groups which found similar results (e.g. Sun et al in [3]). The ongoing experimental investigation presented in this paper focuses on the influence of a droplet laden flow on an axial compressors aerodynamics over the range of relevant incidence flow angles. The result of the series of experiments is a comparison of a dry air compressor flow and a droplet laden air compressor flow at high velocity (Ma > 0.85). The variables were water load and incidence angle. The discussion will investigate the effects of the presence of water droplet on the compressor cascades discharge flow properties and their influence on the relevant performance parameters. For this a discussion of the loss coefficient the detailed discharge flow velocity and the axial velocity density ratio (AVDR) will take place.

Experimental Investigation on Aerodynamic Behavior of a Compressor Cascade in Droplet Laden Flow

2013 ◽  
Vol 136 (6) ◽  
Author(s):  
Birger Ober ◽  
Franz Joos
Keyword(s):  
Experimental Investigation ◽  
Water Droplet ◽  
Gas Turbines ◽  
Renewable Energy Sources ◽  
Water Injection ◽  
Density Ratio ◽  
Research Groups ◽  
Compressor Cascade ◽  
Discharge Flow ◽  
Air Compressor

The possibility to augment the power output of gas turbines by the use of water injection becomes more and more attractive in recent years as unsteadily available renewable energy sources become more present and the need of reserve power rises. Depending on the installed system, water injection may result in a two phase flow inside the compressor. The water droplet laden compressor flow promises benefits in efficiency and to some extent in performance and stability. A promising approach is the stabilizing influence on highly stressed airfoils as experimentally and numerically investigated by different research groups. Multiple numerical investigations have been undertaken by different research groups which found similar results. The ongoing experimental investigation presented in this paper focuses on the influence of a droplet laden flow on an axial compressors' aerodynamics over the range of relevant incidence flow angles. The result of the series of experiments is a comparison of a dry air compressor flow and a droplet laden air compressor flow at high velocity (Ma>0.85). The variables were water load and incidence angle. The discussion will investigate the effects of the presence of water droplet on the compressor cascade's discharge flow properties and their influence on the relevant performance parameters. For this a discussion of the loss coefficient the detailed discharge flow velocity and the axial velocity density ratio will take place.

Experimental Investigation on Droplet Behavior in a Transonic Compressor Cascade

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Niklas Neupert ◽  
Birger Ober ◽  
Franz Joos
Keyword(s):  
Experimental Investigation ◽  
Gas Turbines ◽  
Surface Film ◽  
Flow Channel ◽  
Point Of View ◽  
Compressor Cascade ◽  
Two Phase ◽  
Transonic Compressor ◽  
Droplet Behavior ◽  
Industrial Gas Turbines

In recent years, overspray fogging has become a powerful means for power augmentation of industrial gas turbines (GT). Most of the studies concerning this topic focus on the problem from a thermodynamic point of view. Only a few studies, however, were undertaken to investigate the droplet behavior in the flow channel of a compressor. In this paper, results of experimental investigation of a water laden flow through a transonic compressor cascade are presented. A finely dispersed spray was used in the measurements (D10 < 10 μm). Results of the droplet behavior are shown in terms of shadowgraphy images and images of the blade surface film pattern. The angle of attack, the incoming velocity, and the water load were varied. The qualitative observations are related to laser Doppler and phase Doppler anemometer (LDA/PDA) data taken in the flow channel and at the outlet of the cascade. The data represent a base for numerical and mean line models of two-phase compressor flow.

Active Flow Control Utilizing an Adaptive Blade Geometry and an Extremum Seeking Algorithm at Periodically Transient Boundary Conditions

2021 ◽  
Vol 143 (2) ◽  
Author(s):  
Tobias Werder ◽  
Robert Liebich ◽  
Karl Neuhäuser ◽  
Clara Behnsen ◽  
Rudibert King
Keyword(s):  
Phase Shift ◽  
Flow Control ◽  
Gas Turbines ◽  
Active Flow Control ◽  
Operating Conditions ◽  
Extremum Seeking ◽  
Experimental Investigations ◽  
Compressor Cascade ◽  
Active Flow ◽  
The Impact

Abstract As a consequence of constant volume combustion in gas turbines, pressure waves propagating upstream the main flow into the compressor system are generated leading to incidence variations. Numerical and experimental investigations of stator vanes have shown that active flow control (AFC) by means of adaptive blade geometries is beneficial when such periodic incidence variations occur. A significant risk reduction in a compressor facing disturbances can thereby be achieved concerning stall or choke. Experimental investigations on such an AFC method with simultaneous application of a closed-loop control are missing in order to demonstrate its potential. This work investigates a linear compressor cascade that is equipped with a 3D-manufactured piezo-adaptive blade structure. The utilized actuators are piezoelectric macro-fiber-composites. A throttling device is positioned downstream the trailing edge plane to emulate an unsteady combustion process. Periodic transient throttling events with a frequency of up to 20 Hz cause incidence changes to the blade’s leading edge. Consequently, pressure fluctuations on the blade’s surface occur, having a significant impact on the pressure recovery downstream of the stator cascade. Experimental results of harmonically actuating the piezo-adaptive blade with the corresponding disturbance frequency show that the impact of disturbances can be reduced to approximately 50%. However, this is only effective if the phase shift of the harmonic actuation is adjusted correctly. Using an inadequate phase shift reverses the positive effects, causing the aforementioned stall, choke, or significant losses. In order to find the optimum phase shift, even under varying, possibly unpredictable operating conditions, an extremum seeking controller is presented. This gradient-based approach is minimizing the pressure variance over time by carefully adjusting the phase shift of the harmonic actuation of the AFC system.

The Combined Effect of Axial Velocity Density Ratio and Aspect Ratio on Compressor Cascade Performance

1981 ◽  
Vol 103 (1) ◽  
pp. 247-255 ◽  
Author(s):  
U. Stark ◽  
H. Hoheisel
Keyword(s):  
Aspect Ratio ◽  
Velocity Distribution ◽  
Axial Velocity ◽  
Density Ratio ◽  
Combined Effect ◽  
Experimental Investigations ◽  
Compressor Cascade ◽  
Pressure Distributions ◽  
Contraction Ratio ◽  
Axial Velocity Distribution

The paper describes theoretical and experimental investigations on the combined effect of axial velocity density ratio (AVDR) and aspect ratio (AR) on compressor cascade performance in incompressible and compressible flow. The results presented demonstrate that it is the aspect ratio that defines the axial velocity distribution through the cascade at a given wall shape and contraction ratio. It is further shown that it is, in turn, the axial velocity distribution that decisively determines the local values of pressure distributions as well as the cascade overall parameters like turning angles and loss coefficients.

scholarly journals The Combined Effect of Axial Velocity Density Ratio and Aspect Ratio on Compressor Cascade Performance

1980 ◽  
Author(s):  
U. Stark ◽  
H. Hoheisel
Keyword(s):  
Aspect Ratio ◽  
Velocity Distribution ◽  
Axial Velocity ◽  
Density Ratio ◽  
Combined Effect ◽  
Experimental Investigations ◽  
Compressor Cascade ◽  
Pressure Distributions ◽  
Contraction Ratio ◽  
Axial Velocity Distribution

The paper describes theoretical and experimental investigations on the combined effect of axial velocity density ratio (AVDR) and aspect ratio (AR) on compressor cascade performance in incompressible and compressible flow. The results presented demonstrate that it is the aspect ratio that defines the axial velocity distribution through the cascade at a given wall shape and contraction ratio. It is further shown that it is, in turn, the axial velocity distribution that decisively determines the local values of pressure distributions as well as the cascade overall parameters like turning angles and loss coefficients.

Experimental Investigation on Droplet Behaviour in a Transonic Compressor Cascade

2014 ◽  
Author(s):  
Niklas Neupert ◽  
Birger Ober ◽  
Franz Joos
Keyword(s):  
Experimental Investigation ◽  
Flow Pattern ◽  
Gas Turbines ◽  
Surface Film ◽  
Flow Channel ◽  
Point Of View ◽  
Compressor Cascade ◽  
Two Phase ◽  
Transonic Compressor ◽  
Droplet Behavior

In recent years overspray fogging has become a powerful means for power augmentation of industrial gas turbines. Most of the studies concerning this topic focus on the problem from a thermodynamic point of view as summarized by Eisfeld and Joos [1]. Only a few studies, however, were undertaken to investigate the droplet behavior in the flow channel of a compressor. Eisfeld and Joos [2] and Ober [3] revealed qualitative results showing a large variety of two-phase phenomena present. In this paper results of experimental investigation of a water laden flow through a compressor cascade are presented. A finely dispersed spray was used in the measurements (D10 < 10μm). Results of the droplet behavior in a transonic compressor cascade are shown in terms of shadowgraphy images and images of the blade surface film pattern. The angle of attack, the incoming velocity and the water load were varied to estimate the influence of these parameters on the flow pattern. The qualitative observations of the flow pattern are related to LDA/PDA data of the flow channel and at the outlet of the cascade. The data represents a base for numerical and mean line models of two phase compressor flow concerning droplet-wall interactions as well as flow induced breakup.

Experimental Investigations of the Influence of Waterdroplets in Compressor Cascades

2006 ◽  
Author(s):  
Enno Ulrichs ◽  
Franz Joos
Keyword(s):  
Water Injection ◽  
Suction Side ◽  
Experimental Investigations ◽  
Compressor Cascade ◽  
Two Phase ◽  
Flow Angle ◽  
Water Load ◽  
Phase Doppler Anemometry ◽  
First Results ◽  
Droplet Sizes

This paper presents first results of experiments in a two-phase-flow cascade wind-tunnel. A Phase-Doppler-Anemometry system is used to measure velocity and water droplet-sizes in a compressor cascade. The local velocity with water injected is slower than the air flow without water injection due to droplet inertia and loss of momentum. Ligament formation and breakup caused by Rayleigh-Taylor instabilities is observed at the trailing edge resulting in particle sizes between 20 μm and 30 μm independent of flow velocity and the size of the nozzle used for water injection. Another region in the last third of the suction side is found, where a separation of droplets below 10 μm occurs. A change in flow angle at the cascade outlet is observed depending on water-load and droplet-size in the inlet.

Experimental Investigation on the Performance of a Compressor Airfoil in Droplet Laden Flow

2012 ◽  
Author(s):  
Birger Ober ◽  
Franz Joos
Keyword(s):  
Experimental Investigation ◽  
Gas Turbines ◽  
Air Flow ◽  
Axial Compressor ◽  
Experimental Investigations ◽  
Test Cases ◽  
Incident Flow ◽  
Improve Performance ◽  
Compression Process ◽  
Axial Compressors

One way to improve performance and efficiency of gas turbines is to implement a wet compression process in the gas turbines’ axial compressor. Water droplet laden compressor flows promise benefits in efficiency and to some extent in performance and stability. A promising approach is the stabilizing influence on highly stressed airfoils as numerically predicted by Sun et al. [1]. First systematic experimental investigations have been made [2], but were restricted to a limited number of test cases. The ongoing experimental investigation focuses on the influence of a droplet laden flow on an axial compressors’ aerodynamics over the entire range of relevant incident flow angles. The result is a comparison of a dry air flow and a droplet laden air flow with respect to values of loss coefficient and the range of incident angles which result in a stable compressor flow.

An Experimental Investigation of Loss Reduction With Riblets on Cascade Blade Surfaces and Isolated Airfoils

1990 ◽  
Author(s):  
Chen Fang ◽  
Tang Yan-Ping ◽  
Chen Mao-Zhang
Keyword(s):  
Experimental Investigation ◽  
Drag Reduction ◽  
Experimental Investigations ◽  
Loss Reduction ◽  
Compressor Cascade

Experimental investigations of loss reduction with riblets have been made. Riblets were put on the blade surfaces in different ways in a compressor cascade or on an isolated airfoil. More than 8% drag reduction benefits for an isolated airfoil and more than 10% loss reduction benefits for the compressor cascade have been obtained by using riblets only on blade pressure surfaces rather than on both pressure and suction surfaces. The mechanism underlying these results has been discussed.

scholarly journals Experimental Investigation of the Performance of a Supersonic Compressor Cascade

1988 ◽  
Vol 110 (4) ◽  
pp. 456-466 ◽  
Author(s):  
D. L. Tweedt ◽  
H. A. Schreiber ◽  
H. Starken
Keyword(s):  
Experimental Investigation ◽  
Mach Number ◽  
Flow Direction ◽  
Pressure Ratio ◽  
Density Ratio ◽  
Axial Flow ◽  
Side Wall ◽  
Federal Republic Of Germany ◽  
Compressor Cascade ◽  
Inlet Conditions

Results are presented from an experimental investigation of a linear, supersonic compressor cascade tested in the supersonic cascade wind tunnel facility at the DFVLR in Cologne, Federal Republic of Germany. The cascade was derived from the near-tip section of a high-throughflow axial flow compressor rotor and has a design relative inlet Mach number of 1.61. Test data were obtained over the range of inlet Mach numbers from 1.30 to 1.17. Side-wall boundary layer suction was used to reduce secondary flow effects within the blade passages and to control the axial-velocity-density ratio (AVDR). Flow velocity measurements showing the wave pattern in the entrance region were obtained with a laser anemometer. The unique-incidence relationship for this cascade, relating the supersonic inlet Mach number to the inlet flow direction, is discussed. The influence of static pressure ratio and AVDR on the blade performance is described, and an empirical correlation is used to show the influence of these (independent) parameters for fixed inlet conditions on the exit flow direction and the total-pressure losses.

Sign in / Sign up

Export Citation Format

Share Document