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.

Performance and Boundary Layer Development of a High Turning Compressor Cascade at Sub- and Supercritical Flow Conditions

2012 ◽  
Author(s):  
Christoph Bode ◽  
Dragan Kožulović ◽  
Udo Stark ◽  
Heinz Hoheisel
Keyword(s):  
Boundary Layer ◽  
Mach Number ◽  
Density Ratio ◽  
Boundary Layer Separation ◽  
Experimental Results ◽  
Numerical Code ◽  
Compressor Cascade ◽  
Boundary Layer Development ◽  
Boundary Layer Interaction ◽  
Inlet Angle

Based on current numerical investigations, the present paper reports on new Q2D midspan-calculations and results for the well known high turning (Δβ = 50°) supercritical (Ma1 = 0.85) compressor cascade V2. A Q2D treatment of the problem was chosen in order to avoid the difficult modelling of the porous endwalls in a corresponding 3D approach. All simulations were done with the RANS solver TRACE of the DLR Cologne in combination with modified versions of the Wilcox turbulence model and Langtry/Menter transition model. Existing experimental Q2D midspan-results for the V2 compressor cascade were used to demonstrate the improved ability of the numerical code to determine performance characteristics, blade pressure and Mach number distributions as well as boundary layer parameter and velocity distributions. The loss characteristics show minimum loss regions when plotted against inlet angle or axial velocity density ratio. Within these regions, increasing with decreasing Mach number, the experimental results were adequately predicted. Outside these regions it turned out difficult to reproduce the experimental results due to increasing boundary layer separation. Furthermore, the prediction quality was very good for subsonic conditions (Ma1 = 0.60) and still reasonable for supercritical conditions (Ma1 = 0.85), where shock/boundary layer interaction made the prediction more difficult.

Experimental Investigation of Gas Turbine Axial Diffuser Performance: Part I — Parametric Analysis of Influential Variables

2020 ◽  
Author(s):  
Kenneth Brown ◽  
Stephen Guillot ◽  
Wing Ng ◽  
Lee Iksang ◽  
Kim Dongil ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Mach Number ◽  
Gas Turbines ◽  
Axial Flow ◽  
Flow Distribution ◽  
Initial Study ◽  
Flow Conditions ◽  
Inlet Flow ◽  
Viscous Loss ◽  
Exit Mach Number

Abstract An experimental investigation of the effect of inlet flow conditions and improved geometries on the performance of modern axial exhaust diffusers of gas turbines has been completed. As the first of a two-part series, this article concentrates on characterizing diffuser sensitivity to parametric variations in internal geometry and inlet flow conditions. Full-factorial experiments were carried out on five parameters including the inlet Mach distribution, shape of the support struts, shape of the oil-drain strut, diffuser hade angle, and the hubcap configuration. To enable an efficient sweep of the design space, experiments were performed in this initial study at a down-scaled turbine exit Reynolds number (ReH roughly 3% of the value for an H-class diffuser) and at a full-scale turbine exit Mach number. The study was accomplished in a continuous, cold-flow wind tunnel circuit, and tailored distributions of Mach number, swirl velocity, and radial velocity derived from on-design conditions of an industry diffuser were generated. Measurements included 5-hole probe traverses at planes of interest. Diffuser performance was most sensitive to the inlet Mach distribution with losses of 0.081 points of pressure recovery due to a nonuniform Mach distribution with higher velocity near the hub versus a uniform one. Detailed comparisons of axial flow variation for a top-performing configuration versus related configurations shed physical insight regarding the evolution of kinetic energy distortion into viscous loss in the wake, as well as highlight the benefit of uniform inlet profiles in practice despite the lower theoretical recovery of such cases. The results presented here isolate the inlet flow distribution as a parameter of high interest for further study which is carried out for both on- and off-design conditions in the companion article [1].

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.

Design and Experimental Investigation of a Mixed Flow Supersonic Compressor Stage

1995 ◽  
Author(s):  
Wolfgang Elmendorf ◽  
Harald Kurz ◽  
Heinz E. Gallus
Keyword(s):  
Experimental Investigation ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Strong Shock ◽  
Mixed Flow ◽  
High Pressure Ratio ◽  
Flow Deceleration ◽  
Stage Performance ◽  
Future Demands ◽  
Inlet Conditions

Highly loaded transonic and supersonic compressors appear capable of meeting the future demands of small gas turbines and jet engines. Particularly mixed flow compressors, taking advantage of the increasing circumferential blade speed between rotor inlet and exit, represent a good compromise with regard to high pressure ratio and mass flow on the one hand, and favorable performance characteristics and efficiency on the other. However, operating a supersonic rotor as part of a stage involves a stator characterized by high turning angles, supersonic inlet conditions and a strong flow deceleration. In fact, the stator can be identified as the critical component regarding overall stage performance. Based on experimentally determined rotor exit flow conditions, the first part of this paper describes the design of a tandem stator with a strong shock in the stator entrance region, followed by subsonic flow turning and diffusion. The main thrust of this paper is to present the analytical results obtained in connection with the experimental investigation of the complete stage at design and off-design conditions. Rotor and stator flow as well as the overall stage performance are discussed in detail. The concept of the tandem stator proves to be suitable for managing the extremely high aerodynamic loading in the Stator. Experimental results reveal the design goals to be met in general.

On-Line Compressor Cascade Washing for Gas Turbine Performance Investigation

2011 ◽  
Author(s):  
Uyioghosa Igie ◽  
Pericles Pilidis ◽  
Dimitrios Fouflias ◽  
Ken Ramsden ◽  
Paul Lambart
Keyword(s):  
Gas Turbine ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Axial Flow ◽  
Engine Performance ◽  
Compressor Cascade ◽  
Design Point ◽  
Washing Process ◽  
On Line ◽  
Flow Compressor

On-line compressor washing for industrial gas turbine application is a promising method of mitigating the effects of compressor fouling degradation; however there are still few studies from actual engine experience that are inconclusive. In some cases the authors attribute this uncertainty as a result of other existing forms of degradation. The experimental approach applied here is one of the first of its kind, employing on-line washing on a compressor cascade and then relating the characteristics to a three-dimensional axial flow compressor. The overall performance of a 226MW engine model for the different cases of a clean, fouled and washed engine is obtained based on the changing compressor behavior. Investigating the effects of fouling on the clean engine exposed to blade roughness of 102μm caused 8.7% reduction in power at design point. This is equivalent, typically to 12 months degradation in fouling conditions. Decreases in mass flow, compressor efficiency, pressure ratio and unattainable design point speed are also observed. An optimistic recovery of 50% of the lost power is obtained after washing which lasts up to 10mins. Similarly, a recovery of all the key parameters is achieved. The study provides an insight into compressor cascade blade washing, which facilitates a reliable estimation of compressor overall efficiency penalties based on well established assumptions. Adopting Howell’s theory as well as constant polytropic efficiency, a general understanding of turbomachinery would judge that 50% of lost power recovered is likely to be the high end of what is achievable for the existing high pressure wash. This investigation highlights the obvious benefits of power recovery with on-line washing and the potential to maintain optimum engine performance with frequent washes. Clearly, the greatest benefits accrue when the washing process is initiated immediately following overhaul.

scholarly journals Design, Optimization, and Analysis of a High-Turning Transonic Tandem Compressor Cascade

1997 ◽  
Author(s):  
Anton Weber ◽  
Wolfgang Steinert
Keyword(s):  
Mach Number ◽  
Total Pressure ◽  
Side Wall ◽  
Design Flow ◽  
Basic Question ◽  
Compressor Cascade ◽  
Flow Angle ◽  
Transonic Compressor ◽  
Blade Row ◽  
Transonic Cascade

As a feasibility study for a stator guide vane a highly loaded transonic compressor stator blade row was designed, optimized, and tested in a transonic cascade facility. The flow entering the turning device with an inlet Mach number of 1.06 has to be turned by more than 60° and diffused extremely to leave the blade row without swirl. Therefore, the basic question was: Is it feasible to gain such a high amount of flow turning with an acceptable level of total pressure losses? The geometric concept chosen is a tandem cascade consisting of a transonic blade row with a flow turning of 10° followed by a subsequent high-turning subsonic cascade. The blade number ratio of the two blade rows was selected to be 1:2 (transonic: subsonic). Design and optimization have been performed using a modern Navier-Stokes flow solver under 2D assumptions by neglecting side wall boundary-layer effects. In the design process it was found to be necessary to guide the wake of the low turning transonic blade near the suction surface of the subsonic blade. Furthermore, it is advantageous to enlarge the blade spacing of the ‘wake’ passage in relation to the neighbouring one of the high turning part. The optimized design geometry of the tandem cascade was tested in the transonic cascade windtunnel of the DLR in Cologne. At design flow conditions the experiments confirmed the design target in every aspect. A flow turning of more than 60°, a static pressure ratio of 1.75, and a total pressure loss coefficient of 0.15 was measured. The working range at design inlet Mach number of 1.06 is about 3.5° in terms of the inlet flow angle. A viscous analysis of various operating points showed excellent agreement with the experimental results.

Design of a Highly-Loaded Four-Stage Low-Speed Research Compressor

2008 ◽  
Author(s):  
C. Clemen ◽  
H. Schrapp ◽  
V. Gu¨mmer ◽  
R. Mu¨ller ◽  
M. Ku¨nzelmann ◽  
...  
Keyword(s):  
Static Pressure ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Navier Stokes ◽  
Experimental Investigations ◽  
Flow Measurements ◽  
Low Speed ◽  
Pressure Surface ◽  
Overall Performance ◽  
Inlet Conditions

The present paper describes the design of a new set of blades for the four-stage axial-flow low-speed research compressor (LSRC) at the TU Dresden. The compressor contains nine blade rows: IGV, four rotors and four cantilevered stators designed as repeating stages. The compressor was originally designed and built in the German AG Turbo project. In recent years fourteen builds of the compressor were built and tested [1]. The new design of the NGV (Build A15) has increased pressure ratio and loading compared to the previous builds. The design was performed using a method giving three-dimensionally optimised blades achieving better efficiency than the previous builds with sufficient operating range despite increased loading. The numerical analysis was carried out using a Rolls-Royce 3D-Navier-Stokes solver at design and off-design inlet conditions. The experimental investigations were carried out by the Technical University of Dresden. Overall performance was measured for different speeds and different back-pressures up to compressor stall. Flow field details were measured at a design and a close-to-stall condition using static pressure probes on the blade suction and pressure surface and secondary flow measurements using 5-hole probes.

Experimental Investigation of the Flow in Diffusers Behind an Axial Flow Compressor

1993 ◽  
Author(s):  
T. Zierer
Keyword(s):  
Velocity Distribution ◽  
Radial Velocity ◽  
Boundary Layers ◽  
Axial Flow ◽  
Side Wall ◽  
Pressure Recovery ◽  
Axial Flow Compressor ◽  
Wide Range ◽  
Inlet Conditions ◽  
Flow Compressor

The flow fields of four diffusers situated at the rear of a one-stage axial flow compressor was experimentally investigated. Through modification of the compressor operating point a wide range of variations of the side wall boundary layers and the radial velocity distribution outside of the boundary layers at diffuser inlet could be achieved. The three dimensional flow field at both diffuser inlet and outlet is analysed. Changes of inlet blockage and radial velocity distribution and their resulting effects on pressure recovery are thoroughly presented. Compared with the results of measurements at diffusers, typically with ducted flow inlet conditions, higher values of pressure recovery are observed. Established design rules, based on investigations of diffusers with carefully developed inlet flow, are checked regarding their applicability for diffusers in turbomachine environment.

The Design of an Axial Flow Fan for Application in Large Air-Cooled Heat Exchangers

2012 ◽  
Author(s):  
Francois G. Louw ◽  
Phillipe R. P. Bruneau ◽  
Theodor W. von Backström ◽  
Sybrand J. van der Spuy
Keyword(s):  
Heat Exchangers ◽  
Flow Direction ◽  
Pressure Fluctuations ◽  
Axial Flow ◽  
Pressure Rise ◽  
Volumetric Flow Rate ◽  
Cooling Capacity ◽  
Operating Conditions ◽  
Operating Efficiency ◽  
Inlet Conditions

The heat transfer characteristics of industrial air-cooled heat exchangers (ACHEs) are dependent on the ability of the fan system to deliver sufficient cooling air. However, under normal operating conditions, variable flow direction and strength often subject peripheral fans to distorted inlet conditions with an attendant reduction in overall volumetric flow rate and cooling capacity. In this paper, a design methodology for single-rotor axial flow fans, appropriate for use in large industrial ACHE’s is presented. The primary motivation for this work was to address the issues of robust off-design performance, in particular, distorted inlet flow tolerance. Using this methodology, two 8-bladed prototype fans (B1 and B2) were designed, built and tested in accordance with BS 848 (Type A) standards. The two B-fans have a hub-tip ratio of xh = 0.4 and employ the Clark Y and NASA LS airfoil profiles respectively. Measured performance characteristics were compared to commercial fan designs (V-, DL- and L-fan) used in existing ACHEs. Results indicate that the B-fans have a higher design point operating efficiency. The B-fans also show a steeper fan static pressure rise characteristic compared to the commercial fans, except for the DL-fan, implying a greater tolerance to pressure fluctuations caused by distorted inflows.

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.

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