Experimental Investigation of the Aerodynamic Performance of a Linear Axial Compressor Cascade With Water Droplet Loading

2010 ◽  
Author(s):  
Tjark Eisfeld ◽  
Franz Joos
Keyword(s):  
Water Injection ◽  
Axial Compressor ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Two Dimensional ◽  
Compressor Cascade ◽  
Compressor Rotor ◽  
Two Dimensional Flow ◽  
Wet Compression ◽  
The Impact

Wet compression operation is a commercially attractive way to increase power output and efficiency of a gas turbine cycle. In recent literature the impact of water loading on the aerodynamic performance of the blading has not been entirely clarified yet. The most significant issues of aerodynamics in wet compression are stage rematching and stability. Therefore, these subjects are investigated in a linear compressor rotor cascade. This setup allows an estimation of the aerodynamic performance of the blading from two-dimensional test data at various operating conditions. Moreover, the impact of droplet flow on the two-dimensional flow field of the blade passage is measured in detail in order to understand the deviation of performance parameters. The results indicate that the effect of water injection on compressor aerodynamics is strongly related to the operating condition. It appears that droplet loading has a beneficial effect on the flow at high blade loading.

Experimental Determination of a Four Stage Axial Compressor Map Operating in Wet Compression

2014 ◽  
Author(s):  
J. P. Schnitzler ◽  
I. von Deschwanden ◽  
S. Clauss ◽  
F. K. Benra ◽  
H. J. Dohmen ◽  
...  
Keyword(s):  
Measurement Technique ◽  
Flow Behavior ◽  
Water Injection ◽  
Axial Compressor ◽  
Evaporation Process ◽  
Water Droplets ◽  
Test Rig ◽  
Measurement Results ◽  
Wet Compression ◽  
The Impact

Injecting water in the air upstream of an axial compressor intake is an effective method to increase the efficiency and the power output of a gas turbine application especially at hot days. Reasoned by their complex two phase flow axial compressors which operate in wet compression mode are in the focus of present thermodynamic analysis, numerical investigations and experimental research. Recently the evaporation process of water droplets, especially at high temperature and pressure levels has been investigated with the laser based measurement technique Phase Doppler Particle Analyzer (PDPA) in detail in a stationary test rig at the University of Duisburg-Essen. The focus of these investigations has been laid on the analysis of the evaporation process in a free stream or cross flow behavior without droplet wall interaction. In this paper the first results of the novel four stage axial compressor test rig are published. This test rig is arranged for high amount of water injection with special optical access for laser based measurements. The first part of the paper outlines the general design, geometric facts and aerodynamic reference parameters of the test rig and gives an introduction to the installed conventional measurement technique. Discrete measurement results from dry runs are compared with CFD results to validate the gathered experimental data. In the second part of the paper the previously discussed dry runs are compared with measurement results of runs with water injection. The amount of water to air ratio is varied and the effects on the operating behavior of the four stage axial compressor are pointed out in detail. Furthermore results from the laser based PDPA measurements at the inlet and at the outlet of the compressor outline the impact on the water droplets moving through the compressor in wet compression mode.

Impact of Uniform Surface Roughness on the Aerodynamic Performance of an Axial Compressor Rotor at Different Rotational Speeds

2021 ◽  
Author(s):  
Ashima Malhotra ◽  
Shraman Goswami ◽  
Pradeep A M
Keyword(s):  
Surface Roughness ◽  
Numerical Study ◽  
Axial Compressor ◽  
Aerodynamic Performance ◽  
Performance Loss ◽  
Compressor Rotor ◽  
Multistage Compressor ◽  
Design Speed ◽  
The Impact ◽  
Relative Flow

Abstract The aerodynamic performance of a compressor rotor is known to deteriorate due to surface roughness. It is important to understand this deterioration as it impacts the overall performance of the engine. This paper, therefore, aims to numerically investigate the impact of roughness on the performance of an axial compressor rotor at different rotational speeds. In this numerical study, the simulations are carried out for NASA Rotor37 at 100%, 80%, and 60% of its design speed. with and without roughness on the blade surface. These speeds are chosen because they represent different flow regimes. The front stages of a multistage compressor usually have a supersonic or transonic regime whereas the middle and aft stages have a subsonic regime. Thus, these performance characteristics can give an estimate of the impact on the performance of a multistage compressor. At 100% speed (design speed), the relative flow is supersonic, at 80% of design speed, the relative flow is transonic and at 60% of design speed, the relative flow is subsonic. Detailed flow field investigations are carried out to understand the underlying flow physics. The results indicate that, for the same amount of roughness, the degradation in the performance is maximum at 100% speed where the rotor is supersonic, while the impact is minimum at 60% speed where the rotor is subsonic. Thus, the rotor shock system plays an important role in determining the performance loss due to roughness. It is also observed that the loss increases with increased span for 100% and 80% speeds, but for 60% speed, the loss is almost constant from the hub to the shroud. This is because, with the increased span, the shock strength increases for 100% and 80% speeds, whereas at 60% speed flow is subsonic.

Effect of Interstage Injection on Compressor Flow Characteristic

2019 ◽  
Author(s):  
Inez Von Deschwanden ◽  
Stefan Braun ◽  
Dieter Brillert
Keyword(s):  
Gas Flow ◽  
Fluid Dynamic ◽  
Water Injection ◽  
Operating Conditions ◽  
Wake Flow ◽  
Water Evaporation ◽  
Water Spray ◽  
Trailing Edge ◽  
Wet Compression ◽  
The Impact

Abstract Wet compression is a widely used approach to enhance the compressor performance of gas turbine units. For wet compression, a water-spray consisting of tiny droplets is injected into the air inlet duct of the compressor. A multi-phase flow of humid air and water droplets enters the compressor. The continued water evaporation inside the compressor stages causes further cooling during the compression process. Water injection between the compressor stages is called interstage injection. An advantage of interstage injection compared to wet compression is the optimized injection of water at specific positions inside the compressor. The amount of injected water can be adopted to the specific operating conditions of the different injection positions with the ideal of isothermal compression. Interstage injection can be realized by several techniques. This paper focuses on interstage injection of water from the trailing edge of stator blades. The water spray is generated in the complex wake flow of the airfoil. This leads to strong interaction between the water spray and the carrier gas flow. In this paper, especially the impact of water injection on the air flow and the spread of the spray is investigated. Phase Doppler Anemometry (PDA) measurements enable two dimensional velocity measurements linked with the droplet size. The comparison of PDA measurements and Computational Fluid Dynamic (CFD) calculations of the dry gas flow allows for the identification of flow instabilities due to interstage injection. Within this publication, a significant influence of the water injection from the trailing edge on the carrier flow is identified. Furthermore, the ability of the spray to spread widely into the flow demonstrates that water injection from the trailing edge is a promising technique for interstage injection.

Numerical Investigation of the Solidity Effect on Linear Compressor Cascades

2014 ◽  
Author(s):  
J. Sans ◽  
M. Resmini ◽  
J.-F. Brouckaert ◽  
S. Hiernaux
Keyword(s):  
Numerical Investigation ◽  
State Of The Art ◽  
Leading Edge ◽  
Operating Conditions ◽  
Compressor Cascade ◽  
Minimum Loss ◽  
Low Speed ◽  
High Mach ◽  
The Stability ◽  
The Impact

Solidity in compressors is defined as the ratio of the aerodynamic chord over the peripheral distance between two adjacent blades, the pitch. This parameter is simply the inverse of the pitch-to-chord ratio generally used in turbines. Solidity must be selected at the earliest design phase, i.e. at the level of the meridional design and represents a crucial step in the whole design process. Most of the existing studies on this topic rely on low-speed compressor cascade correlations from Carter or Lieblein. The aim of this work is to update those correlations for state-of-the-art controlled diffusion blades, and extend their application to high Mach number flow regimes more typical of modern compressors. Another objective is also to improve the physical understanding of the solidity effect on compressor performance and stability. A numerical investigation has been performed using the commercial software FINE/Turbo. Two different blade profiles were selected and investigated in the compressible flow regime as an extension to the low-speed data on which the correlations are based. The first cascade uses a standard double circular arc profile, extensively referenced in the literature, while the second configuration uses a state-of-the-art CDB, representative of low pressure compressor stator mid-span profile. Both profiles have been designed with the same inlet and outlet metal angles and the same maximum thickness but the camber and thickness distributions, the stagger angle and the leading edge geometry of the CDB have been optimized. The determination of minimum loss, optimum incidence and deviation is addressed and compared with existing correlations for both configurations and various Mach numbers that have been selected in order to match typical booster stall and choke operating conditions. The emphasis is set on the minimum loss performance at mid-span. The impact of the solidity on the operating range and the stability of the cascade are also studied.

Experimental Investigation Into the Effects of the Steady Wake-Tip Clearance Vortex Interaction in a Compressor Cascade

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Andreas Krug ◽  
Peter Busse ◽  
Konrad Vogeler
Keyword(s):  
Flow Field ◽  
Experimental Studies ◽  
Axial Compressor ◽  
Field Measurements ◽  
Tip Clearance ◽  
Compressor Cascade ◽  
Unsteady Interaction ◽  
Linear Compressor Cascade ◽  
Tip Clearance Vortex ◽  
The Impact

An important aspect of the aerodynamic flow field in the tip region of axial compressor rotors is the unsteady interaction between the tip clearance vortex (TCV) and the incoming stator wakes. In order to gain an improved understanding of the mechanics involved, systematic studies need to be performed. As a first step toward the characterization of the dynamic effects caused by the relative movement of the blade rows, the impact of a stationary wake-induced inlet disturbance on a linear compressor cascade with tip clearance will be analyzed. The wakes were generated by a fixed grid of cylindrical bars with variable pitch being placed at discrete pitchwise positions. This paper focuses on experimental studies conducted at the newly designed low-speed cascade wind tunnel in Dresden. The general tunnel configuration and details on the specific cascade setup will be presented. Steady state flow field measurements were carried out using five-hole probe traverses up- and downstream of the cascade and accompanied by static wall pressure readings. 2D-particle image velocimetry (PIV) measurements complemented these results by visualizing the blade-to-blade flow field. Hence, the structure of the evolving secondary flow system is evaluated and compared for all tested configurations.

The Impact of Manufacturing Variations on Performance of a Transonic Axial Compressor Rotor

2018 ◽  
Author(s):  
Marcus Lejon ◽  
Niklas Andersson ◽  
Lars Ellbrant ◽  
Hans Mårtensson
Keyword(s):  
Flow Field ◽  
Geometric Mean ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Mean Deviation ◽  
Design Intent ◽  
Compressor Rotor ◽  
Measuring Machine ◽  
The Mean ◽  
The Impact

In this paper, the impact of manufacturing variations on performance of an axial compressor rotor are evaluated at design rotational speed. The geometric variations from the design intent were obtained from an optical coordinate measuring machine and used to evaluate the impact of manufacturing variations on performance and the flow field in the rotor. The complete blisk is simulated using 3D CFD calculations, allowing for a detailed analysis of the impact of geometric variations on the flow. It is shown that the mean shift of the geometry from the design intent is responsible for the majority of the change in performance in terms of mass flow and total pressure ratio for this specific blisk. In terms of polytropic efficiency, the measured geometric scatter is shown to have a higher influence than the geometric mean deviation. The geometric scatter around the mean is shown to impact the pressure distribution along the leading edge and the shock position. Furthermore, a blisk is analyzed with one blade deviating substantially from the design intent, denoted as blade 0. It is shown that the impact of blade 0 on the flow is largely limited to the blade passages that it is directly a part of. The results presented in this paper also show that the impact of this blade on the flow field can be represented by a simulation including 3 blade passages. In terms of loss, using 5 blade passages is shown to give a close estimate for the relative change in loss for blade 0 and neighboring blades.

Cold Blade Profile Generation Methodology for Compressor Rotor Blades Using FSI Approach

2017 ◽  
Author(s):  
Kirubakaran Purushothaman ◽  
Sankar Kumar Jeyaraman ◽  
Ajay Pratap ◽  
Kishore Prasad Deshkulkarni
Keyword(s):  
Aspect Ratio ◽  
Rotor Blade ◽  
Axial Compressor ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Blade Profile ◽  
Interaction Technique ◽  
Compressor Rotor ◽  
Blade Shape ◽  
Blade Geometry

This paper describes a methodology for obtaining correct blade geometry of high aspect ratio axial compressor blades during running condition taking into account of blade untwist and bending. It discusses the detailed approach for generating cold blade geometry for axial compressor rotor blades from the design blade geometry using fluid structure interaction technique. Cold blade geometry represents the rotor blade shape at rest, which under running condition deflects and takes a new operating blade shape under centrifugal and aerodynamic loads. Aerodynamic performance of compressor primarily depends on this operating rotor blade shape. At design point it is expected to have the operating blade shape same as the intended design blade geometry and a slight mismatch will result in severe performance deterioration. Starting from design blade profile, an appropriate cold blade profile is generated by applying proper lean and pre-twist calculated using this methodology. Further improvements were carried out to arrive at the cold blade profile to match the stagger of design profile at design operating conditions with lower deflection and stress for first stage rotor blade. In rear stages, thermal effects will contribute more towards blade deflection values. But due to short blade span, deflection and untwist values will be of lower values. Hence difference between cold blade and design blade profile would be small. This methodology can especially be used for front stage compressor rotor blades for which aspect ratio is higher and deflections are large.

Analysis of mistuned forced response in an axial high-pressure compressor rig with focus on Tyler–Sofrin modes

2019 ◽  
Vol 123 (1261) ◽  
pp. 356-377
Author(s):  
F. Figaschewsky ◽  
A. Kühhorn ◽  
B. Beirow ◽  
T. Giersch ◽  
S. Schrape
Keyword(s):  
Axial Compressor ◽  
Maximum Amplitude ◽  
Forced Response ◽  
Operating Conditions ◽  
Cfd Simulations ◽  
High Pressure Compressor ◽  
Engine Order ◽  
Stator Vane ◽  
Vibration Responses ◽  
The Impact

ABSTRACTThis paper aims at contributing to a better understanding of the effect of Tyler–Sofrin Modes (TSMs) on forced vibration responses by analysing a 4.5-stage research axial compressor rig. The first part starts with a brief review of the involved physical mechanisms and necessary prerequisites for the generation of TSMs in multistage engines. This review is supported by unsteady CFD simulations of a quasi 2D section of the studied engine. It is shown that the amplitude increasing effect due to mistuning can be further amplified by the presence of TSMs. Furthermore, the sensitivity with respect to the structural coupling of the blades and the damping as well as the shape of the expected envelope is analysed.The second part deals with the Rotor 2 blisk of the research compressor rig. The resonance of a higher blade mode with the engine order of the upstream stator is studied in two different flow conditions realised by different variable stator vane (VSV) schedules which allows to separate the influence of TSMs from the impact of mistuning. A subset of nominal system modes representation of the rotor is used to describe its mistuned vibration behaviour, and unsteady CFD simulations are used to characterise the present strength of the TSMs in the particular operating conditions. Measured maximum amplitude vs blade pattern and frequency response functions are compared against the predictions of the aeromechanical models in order to assess the strength of the TSMs as well as its influence on vibration levels.

scholarly journals Blockage Development in a Transonic, Axial Compressor Rotor

1997 ◽  
Author(s):  
Kenneth L. Suder
Keyword(s):  
Boundary Layer ◽  
Axial Compressor ◽  
Flow Region ◽  
Tip Clearance ◽  
Surface Boundary ◽  
Core Flow ◽  
The Core ◽  
Compressor Rotor ◽  
Transonic Axial Compressor ◽  
The Impact

A detailed experimental investigation to understand and quantify the development of blockage in the flow field of a transonic, axial flow compressor rotor (NASA Rotor 37) has been undertaken. Detailed laser anemometer measurements were acquired upstream, within, and downstream of a transonic, axial compressor rotor operating at 100%, 85%, 80%, and 60% of design speed which provided inlet relative Mach numbers at the blade tip of 1.48, 1.26, 1.18, and 0.89 respectively. The impact of the shock on the blockage development, pertaining to both the shock / boundary layer interactions and the shock / tip clearance flow interactions, is discussed. The results indicate that for this rotor the blockage in the endwall region is 2–3 times that of the core flow region, and the blockage in the core flow region more than doubles when the shock strength is sufficient to separate the suction surface boundary layer.

Aerodynamic Instability and Life Limiting Effects of Inlet and Interstage Water Injection Into Gas Turbines

2005 ◽  
Author(s):  
Klaus Brun ◽  
Rainer Kurz ◽  
Harold R. Simmons
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Water Injection ◽  
Axial Compressor ◽  
Careful Analysis ◽  
Operating Conditions ◽  
Aerodynamic Stability ◽  
Surge Margin ◽  
Power Enhancement ◽  
Aerodynamic Instability

Gas turbine power enhancement technologies such as inlet fogging, interstage water injection, saturation cooling, inlet chillers, and combustor injection are being employed by end-users without evaluating the potentially negative effects these devices may have on the operational integrity of the gas turbine. Particularly, the effect of these add-on devices, off-design operating conditions, non-standard fuels, and compressor degradation/fouling on the gas turbine’s axial compressor surge margin and aerodynamic stability is often overlooked. Nonetheless, compressor aerodynamic instabilities caused by these factors can be directly linked to blade high-cycle fatigue and subsequent catastrophic gas turbine failure; i.e., a careful analysis should always proceed the application of power enhancement devices, especially if the gas turbine is operated at extreme conditions, uses older internal parts that are degraded and weakened, or uses non-standard fuels. This paper discusses a simplified method to evaluate the principal factors that affect the aerodynamic stability of a single shaft gas turbine’s axial compressor. As an example, the method is applied to a frame type gas turbine and results are presented. These results show that inlet cooling alone will not cause gas turbine aerodynamic instabilities but that it can be a contributing factor if for other reasons the machine’s surge margin is already slim. The approach described herein can be employed to identify high-risk applications and bound the gas turbine operating regions to limit the risk of blade life reducing aerodynamic instability and potential catastrophic failure.

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