Wake Induced Time-Variant Aerodynamics Including Rotor-Stator Axial Spacing Effects

1981 ◽  
Vol 103 (1) ◽  
pp. 59-66 ◽  
Author(s):  
S. Fleeter ◽  
R. L. Jay ◽  
W. A. Bennett
Keyword(s):  
Large Scale ◽  
Primary Source ◽  
Forced Response ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Experimental Program ◽  
Axial Distance ◽  
Spacing Effects ◽  
Spacing Ratio ◽  
Wide Range

The overall objective of this experimental program was to quantify the effects of rotor-stator axial spacing on the fundamental time-variant aerodynamics relevant to forced response in turbomachinery. This was accomplished in a large-scale, low-speed, single-stage research compressor which permitted two rotor-stator axial spacing ratios representative of those found in advanced design compressors to be investigated. At each value of the axial spacing ratio, the aerodynamically induced fluctuating surface pressure distributions on the downstream vane row, with the primary source of excitation being the upstream rotor wakes, were measured over a wide range of compressor operating conditions. The velocity fluctuations created by the passage of the rotor blades were measured in the nonrotating coordinate system. Data obtained described the variation of the rotor wake with both loading and axial distance from the rotor as parameters. These data also served as a reference in the analysis of the resulting time-variant pressure signals on the vane surfaces.

scholarly journals Composite UHBR Fan for Forced Response and Flutter Investigations

2021 ◽  
Author(s):  
Torben Eggers ◽  
Jens Friedrichs ◽  
Jan Goessling ◽  
Joerg R. Seume ◽  
Nunzio Natale ◽  
...  
Keyword(s):  
Forced Response ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Future Research ◽  
Test Case ◽  
Composite Blade ◽  
Wide Range ◽  
Open Test ◽  
Performance Specifications ◽  
Transonic Fan

Abstract In the CA3ViAR (Composite fan Aerodynamic, Aeroelastic, and Aeroacoustic Validation Rig) project, a composite low-transonic fan is designed and tested. The aim is a scaled ultra-high bypass ratio (UHBR) fan with state-of-the-art aerodynamic performance and composite rotor blades, which features aeroelastic phenomena, e.g. forced response by inlet distortions and flutter, under certain operating points within the wind tunnel. In this paper, the aerodynamic and aeroelastic design process starting from the overall performance specifications to a threedimensional numerical model is described. A target of eigen-frequency and twist-to-plunge ratio is specified such that flutter occurs at desired operating conditions with a sufficient margin with respect to the working line. Different materials and layups of the composite blade are analyzed to reach the structural target. The fan should serve as an open test case to advance the future research on aerodynamic, aeroelastic, and aeroacoustic performance investigations in a wide range of operating conditions. A preliminary fan stage design is presented in this paper.

On the Probabilistic Endurance Prediction Approach for Turbomachinery Blades and Vanes

2020 ◽  
Author(s):  
Davendu Y. Kulkarni ◽  
Caetano Peng
Keyword(s):  
Robust Design ◽  
Product Life Cycle ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Probabilistic Methods ◽  
Wide Range ◽  
Deterministic Methods ◽  
Stator Vane ◽  
Turbomachinery Blades ◽  
Prediction Approach

Abstract The design and aeromechanical assessment of turbomachinery blades and vanes comprises a wide range of complex processes that tend to be based on conventional deterministic methods. These processes often provide a ‘snapshot’ evaluation of the new component designs at the nominal operating conditions. While the deterministic methods can predict the high cycle fatigue (HCF) endurance with reasonable accuracy; they assume that the conservative safety factors applied to cover for the parametric variations, uncertainties and unknowns will not change during the product life cycle. This approach is intended to be conservative and in some cases may overlook the lack of robustness. The present paper proposes a robust design analysis approach based on probabilistic methodology for the aeromechanical assessment of rotor blades and stator vanes of turbomachinery. The robust design approach can account explicitly for the effects of design and manufacturing variability. This methodology can reduce the levels of conservatism in the deterministic approach and can provide a more thorough risk assessment. This paper offers a generalised aeromechanical analysis formulation based on probabilistic methods to evaluate the HCF capability of turbomachinery components. Herein, this methodology is demonstrated by using a typical stator vane of an aero engine compressor and it is based on Monte-Carlo and DOE simulations. The methodology consists of parametric sensitivity studies and identification of the most influential parameters that control the HCF endurance. Future ideas and roadmap of the aeromechanical probabilistic analysis capability development are also discussed.

Hydro Francis Runner Stability and Forced Response Calculations

2019 ◽  
Author(s):  
Charles Seeley ◽  
Sunil Patil ◽  
Andy Madden ◽  
Stuart Connell ◽  
Gwenael Hauet ◽  
...  
Keyword(s):  
Large Scale ◽  
Forced Response ◽  
Operating Conditions ◽  
Mode Shapes ◽  
Symmetric Model ◽  
Validation Data ◽  
Fea Model ◽  
Forcing Function ◽  
Cyclic Symmetric ◽  
Work Done

Abstract Hydroelectric power generation accounts for 7% of the total world electric energy production. Francis turbines are often employed in large-scale hydro projects and represent 60% of the total installed base. Outputs up to 800 MW are available and efficiencies of 95% are common. Cost, performance, and design cycle time are factors that continue to drive new designs as well as retrofits. This motivates the development of more sophisticated analysis tools to better assess runner performance earlier in the design phase. The focus of this paper is to demonstrate high fidelity and time-efficient runner damping and forced response calculations based on one-way fluid-structure interaction (FSI) using loosely coupled commercial finite element analysis (FEA) and computational fluid dynamics (CFD) codes. The runner damping is evaluated based on the work done by the fluid on the runner. The calculation of the work first involves determining the runner mode shapes and natural frequencies using a cyclic symmetric FEA model with structural elements to represent the runner hardware, and acoustic fluid elements to represent the mass loading effect of the fluid. The mode shapes are then used in a transient CFD calculation to determine the damping which represents the work done by the fluid on the runner. Positive damping represents stability from flutter perspective while negative damping represents unstable operating conditions. A transient CFD calculation was performed on a runner to obtain engine order forcing function from upstream stationary vanes. This unsteady forcing function was mapped to the FEA model. Care is taken to account for the proper inter-blade phase angle on the cyclic symmetric model. The hydraulic damping from flutter calculations was also provided as input to the forced response. The forced response is then determined using this equivalent proportional damping and modal superposition of the FEA model that includes both the structural and acoustic elements. Results of the developed analysis procedure are presented based on the Tokke runner, that has been the basis of several studies through the Norwegian HydroPower Center. Unique features of the workflow and modeling approaches are discussed in detail. Benefits and challenges for both the FEA model and the CFD model are discussed. The importance of the hydraulic damping, that is traditionally ignored in previous analysis is discussed as well. No validation data is available for the forced response, so this paper is focused on the methodology for the calculations.

Development of a Novel Axial Compressor Generation for Industrial Applications: Part 2 — Blade Mechanics

2014 ◽  
Author(s):  
Dirk Anding ◽  
Henning Ressing ◽  
Klaus Hörmeyer ◽  
Roland Pisch ◽  
Kai Ziegler
Keyword(s):  
High Efficiency ◽  
Axial Compressor ◽  
Forced Response ◽  
Operating Conditions ◽  
Strain Gauges ◽  
Blade Design ◽  
Operating Range ◽  
Resonance Frequencies ◽  
Wide Range ◽  
Blade Vibrations

Blade vibrations resulting in alternating stresses are often the critical factor in determining blade life. Indeed, many of the failures experienced by turbomachinery blades occur due to high-cycle fatigue caused by blade vibrations. These vibrations can arise either through self-excited oscillations known as flutter or through aerodynamic forcing of the blades from factors such as periodic wakes from up and/or downstream vanes or unsteady flow phenomena such as compressor surge. The current paper deals with the design and the analytical and experimental verification of the axial blading for a new generation of industrial compressors, a hybrid axial compressor that combines the advantages of conventional industrial compressors — broad operating range and high efficiency — with the advantages of gas turbine compressors — high power-density and high stage pressure ratios. Additionally, the surge robustness of this novel compressor blading has been greatly improved. During the development phase extensive efforts were made to ensure safe operation for future service life. This was achieved by designing blades that will not flutter, do not have high resonance amplitudes throughout their entire operating range and are extremely robust against surge. This strongly increased robustness of the new compressor blading was achieved by the implementation of a “wide-chord” blade design in all rotor blade rows in combination with a proper tuning of resonance frequencies throughout the entire operating range. For the verification of the new blading well-established methods accepted by industry were used such as CFD and FEA. Furthermore, coupling of the two into a method referred to as Fluid Structure Interaction (FSI) was used to more closely investigate the interaction of flow and structural dynamics phenomena. These analytical techniques have been used in conjunction with extensive testing of a scaled test compressor, which was operated at conditions of dynamic similitude (matching of scaled blade vibration frequencies, flow conditions, and Mach number) with full-scale operational conditions. Strain gauges placed on the blades and a state of the art technique known as “tip timing” were used to verify blade vibrations over a wide range of combinations of guide vane positions and rotational speeds. No propensity was found of any of the blades to develop high vibration amplitudes at any of the operating conditions investigated in the rig tests. The comparison of non-linear forced response analyses and the rig test results from strain gauges and tip timing showed close agreement, verifying the analysis techniques used. In conclusion it can be stated that the blade design exhibits a very high level of safety against vibrations within the entire operating range and during surge.

Plasma Display Materials

MRS Bulletin ◽  
2002 ◽  
Vol 27 (11) ◽  
pp. 898-902 ◽  
Author(s):  
Kinzo Nonomura ◽  
Hidetaka Higashino ◽  
Ryuichi Murai
Keyword(s):  
Large Scale ◽  
Protective Layer ◽  
Operating Conditions ◽  
Protective Layers ◽  
Blue Phosphor ◽  
Wide Range ◽  
Plasma Display ◽  
Deterioration Mechanism ◽  
Discharge Gas ◽  
Gas Efficiency

AbstractRecent trends in the development of plasma display panels (PDPs) are reviewed in this article with special emphasis on materials. New developments in the panel structure, discharge gases and phosphors used, and drive methods have improved many of the display characteristics over a wide range of operating conditions. As a result, much progress has been seen in large-scale panel development; for example, 50-in. and 61-in. PDPs have been commercialized. Improvements in phosphor longevity, discharge gas efficiency, and characteristics of the protective layers can be attributed in part to materials solutions. The longevity of the blue phosphor has been improved by the development of new materials and a greater understanding of the phosphor deterioration mechanism. The luminous efficiency has been greatly increased by the use of high-density Xe gas. The protective-layer characteristics have been improved as a result of advancements in processes, materials, and analytical methods.

History of Short-Duration Measurement Programs Related to Gas Turbine Heat Transfer, Aerodynamics, and Aeroperformance at Calspan and OSU

2013 ◽  
Author(s):  
Michael Dunn ◽  
Randall Mathison
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Gas Turbine ◽  
Short Duration ◽  
Forced Response ◽  
Experimental Techniques ◽  
Experimental Program ◽  
Inlet Temperature ◽  
Wide Range ◽  
Purge Flow

Short-duration facilities have been used for the past thirty-five years to obtain measurements of heat transfer, aerodynamic loading, vibratory response, film-cooling influence, purge flow migration, and aeroperformance for full-stage high-pressure turbines operating at design corrected conditions of flow function, corrected speed, and stage pressure ratio. This paper traces the development of experimental techniques now in use at The Ohio State University (OSU) Gas Turbine Laboratory (GTL) from initial work in this area at the Cornell Aeronautical Laboratory (CAL, later to become Calspan) in 1975 through to the present. It is intended to summarize the wide range of research that can be performed with a short-duration facility and highlight the types of measurements that are possible. Beginning with heat-flux measurements for the vane and blade of a Garrett TFE 731-2 HP turbine stage with vane pressure-surface slot cooling, the challenge of each experimental program has been to provide data to aid turbine designers in understanding the relevant flow physics and help drive the advancement of predictive techniques. Through many different programs, this has involved collaborators at a variety of companies and experiments performed with turbine stages from Garrett, Allison, Teledyne, Pratt and Whitney, General Electric Aviation, Rocketdyne, Westinghouse, and Honeywell. The Vane/Blade Interaction measurement and CFD program, which ran from the early eighties until 2000, provided a particularly good example of what can be achieved when experimentalists and computational specialists collaborate closely. Before conclusion of this program in 2000, the heat-flux and pressure measurements made for this transonic turbine operated with and without vane trailing edge cooling flow were analyzed and compared to predictive codes in conjunction with engineers at Allison, United Technologies Research Center, Pratt and Whitney, and GE Aviation in jointly published papers. When the group moved to OSU in 1995 along with the facility used at Calspan, refined techniques were needed to meet new research challenges such as investigating blade damping and forced response, measuring aeroperformance for different configurations, and preparing for advanced cooling experiments that introduced complicating features of an actual engine to further challenge computational predictions. This required conversion of the test-gas heating method from a shock-tunnel approach to a blowdown approach using a combustor emulator to also create inlet temperature profiles, the development of instrumentation techniques to work with a thin-walled airfoil with backside cooling, and the adoption of experimental techniques that could be used to successfully operate fully cooled turbine stages (vane row cooled, blade row cooled, and proper cavity purge flow provided). Further, it was necessary to develop techniques for measuring the aeroperformance of these fully cooled machines.

The Time-Variant Aerodynamic Response of a Stator Row Including the Effects of Airfoil Camber

1980 ◽  
Vol 102 (2) ◽  
pp. 334-342 ◽  
Author(s):  
S. Fleeter ◽  
W. A. Bennett ◽  
R. L. Jay
Keyword(s):  
Flat Plate ◽  
Pressure Difference ◽  
Large Scale ◽  
State Of The Art ◽  
Dynamic Pressure ◽  
Pressure Coefficient ◽  
Forced Response ◽  
Phase Lag ◽  
Forcing Function ◽  
Wide Range

An experimental investigation was conducted to quantitatively determine the validity and applicability of state-of-the-art transverse gust cascade analyses. This was accomplished by obtaining fundamental time-variant forced response data at realistic values of key parameters in a large-scale, low-speed, single-stage research compressor. The forcing function, the velocity defect created by the rotor blade wakes, was measured with a crossed hot-wire probe. The resulting time-variant aerodynamic response was measured by means of flush mounted high response pressure transducers on both flat plate and cambered airfoil stator vane rows over a wide range of incidence angles. These dynamic data were then analyzed to determine the chordwise variation of the unsteady pressure difference in terms of a dimensionless dynamic pressure coefficient and an aerodynamic phase lag referenced to a transverse gust at the leading edge of the vanes. These dimensionless pressure difference data were all correlated with predictions obtained from a state-of-the-art compressible transverse gust, flat plate cascade analysis. Correlation of the classical flat plate unsteady data with the predictions permitted the range of validity of the analysis to be assessed in terms of incidence angle. Correlation of the cambered vane unsteady data with those for the flat plate and with the predictions allowed the effects of airfoil camber as well as the applicability of the flat plate prediction to realistic cambered airfoils to be quantitatively determined.

Numerical Prediction of Pressure Gradient of Slurry Flows in Horizontal Pipes

2013 ◽  
Author(s):  
Gianandrea Vittorio Messa ◽  
Michael Malin ◽  
Stefano Malavasi
Keyword(s):  
Pressure Gradient ◽  
Large Scale ◽  
Solid Phase ◽  
Fluid Model ◽  
Operating Conditions ◽  
Sand Particle ◽  
Horizontal Pipes ◽  
Numerical Predictions ◽  
Wide Range ◽  
Solid Liquid

Pipe flows of solid-liquid mixtures in the form of slurries are frequently encountered in many engineering applications. The pressure gradient is perhaps the most serious concern of designers, as it dictates the selection of pump capacity. Due to their versatility, in the sense of applicability to large scale systems and more complex flows, CFD models have been an attractive tool in recent years. The fully-suspended flow of solid-liquid slurries in horizontal pipes is simulated by means of a two-fluid model. In particular, the effect of the wall boundary condition for the solid phase on the pressure gradient is discussed, considering different alternatives. The numerical predictions were compared to experimental measurements from open literature over a wide range of operating conditions, in terms of pipe diameter (53.2 to 103 mm), grain material (glass beads and sand), particle size (90 to 370 μm), slurry velocity (1.5 to 8 m/s), and mean solids concentration (up to 40%). The equilibrium wall function of Launder and Spalding for smooth walls proved adequate for fully-suspended flows, but overestimates the losses if the particles are large compared to the boundary layer thickness. Guidelines are provided for defining the numerical set-up and evaluating the uncertainty of the numerical results.

Experimental Investigation of Tip Cavitating Vortices in Axial-Flow Pump

2017 ◽  
Author(s):  
Desheng Zhang
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Axial Flow ◽  
Operating Conditions ◽  
High Speed Imaging ◽  
Cavitation Performance ◽  
Stable Operating ◽  
Wide Range ◽  
Axial Flow Pump ◽  
Flow Pump

The primary goal of this work focuses on the cavitating vortices in the tip region of an axial-flow pump with 3 and 4 blades mainly based on the high-speed imaging experiments, with special attention on the trajectory and dynamics of a large-scale cavitation structure. The hydraulic and cavitation performance between two impellers were compared, and it can be found that the model with 4 blades has a relative wide range of stable operating conditions as well as the better anti-cavitation ability. By the analysis of the cavitation curves, it confirms that the highly unsteady tip cavitation cloud near the blade trailing edge should be responsible for the severe degradation of the performance. According to the detailed study on the cavitation evolution in the two impellers, it is observed that the trajectory of tip cavitating vortices for different flow rates seems very similar determined by the operating conditions. However, the dynamics varies significantly, which is associated with the blade loading and flow passage width.

Biological Removal of Chlorate from Bleaching Plant Effluent

1994 ◽  
Vol 29 (5-6) ◽  
pp. 365-372 ◽  
Author(s):  
Åsa Malmqvist ◽  
Thomas Welander
Keyword(s):  
Process Design ◽  
Laboratory Tests ◽  
Large Scale ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Process Efficiency ◽  
Laboratory System ◽  
Loading Capacity ◽  
Wide Range ◽  
Suspended Carrier

Biological chlorate removal was studied on a laboratory and a pilot scale with the aim of optimizing process design and operating conditions with respect to process efficiency, stability and economy. The results showed a suspended-carrier biofilm process design to be suitable for biological chlorate removal. In the laboratory tests, at pH 7 and 37°C, a complete removal of chlorate could be maintained at hydraulic retention times (HRTs) as short as 24 min. A longer HRT (1.5 h) was required for complete chlorate removal in the pilot test, due to a lower degree of filling with carrier material (25% versus 50% of the reactor volume), higher process temperature, and leakage of oxygen into the process. However, it is assumed that the loading capacity of a large-scale process would approach that of the laboratory system if the operating conditions were the same. Laboratory tests showed chlorate reduction to be possible within a wide range of pH values and temperatures, although the process stability and loading capacity were strongly affected by changes in these parameters. The results of the laboratory and pilot scale studies, using a suspended-carrier process design, show biological treatment to be an economically viable and efficient process for the removal of chlorate from bleaching plant effluents.

Sign in / Sign up

Export Citation Format

Share Document