Experimental investigation of the 3D unsteady flow field downstream of axial fans

The unsteady flow field produced by a tandem cylinder system with the upstream cylinder yawed to the mean flow direction is investigated for upstream cylinder yaw angles from α = 60° to α = 90°. Multi-point fluctuating surface pressure and hotwire measurements were conducted at various spanwise positions on both the upstream and downstream cylinders. The results indicate that yawing the front cylinder to the mean flow direction causes the pressure and velocity spectra on the upstream and downstream cylinders to become more broadband than for a regular tandem cylinder system, and reduces the magnitude of the peak associated with the vortex-shedding. However, span-wise correlation and coherence measurements indicate that the vortex-shedding is still present and was being obscured by the enhanced three-dimensionality that the upstream yawed cylinder caused and was still present and correlated from front to back, at least for the larger yaw angles investigated. When the cylinder was yawed to α = 60°, the pressure fluctuations became extremely broadband and exhibited shorter spanwise correlation.

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Experimental Investigation of the Steady and Unsteady Flow Field in a Single Stage Low Pressure Axial Compressor With a Circumferential Groove Casing Treatment

Volume 7: Turbomachinery, Parts A, B, and C ◽

10.1115/gt2010-23474 ◽

2010 ◽

Author(s):

N. Van de Wyer ◽

B. Farkas ◽

J. Desset ◽

J. F. Brouckaert ◽

J.-F. Thomas ◽

...

Keyword(s):

Experimental Investigation ◽

Flow Field ◽

Unsteady Flow ◽

Axial Compressor ◽

Low Pressure ◽

Fast Response ◽

Single Stage ◽

Compressor Stage ◽

Casing Treatment ◽

Circumferential Groove

This paper deals with the experimental investigation of the influence of a circumferential groove casing treatment on the performance and stability margin of a single stage low pressure axial compressor. The design of the compressor stage is representative of a booster stage for the new counter-rotating turbofan engine architecture and is characterized by unusually high loading and flow coefficients. The choice of the circumferential groove is described on the basis of a numerical parametric study on the number of grooves, the axial position, the depth and width of the groove. The experiments were performed at a Reynolds number corresponding to cruise conditions in the von Karman Institute closed loop high speed compressor test rig R4. The detailed performance characterization of the compressor stage with casing treatment was mapped at four operating points from choke to stall at design speed. The compressor stall limit was determined at several other off-design speeds. Detailed steady and unsteady measurements were performed to determine the flow field characteristics of the rotor and of the complete stage. Conventional pressure, temperature and directional probes were used along with fast response pressure sensors in the rotor casing and in the groove. Simultaneous traverses with a fast response total pressure probe were used to map the unsteady flow field at the rotor exit allowing an experimental capture of the tip leakage vortex path and extension through the rotor passage. A comparison of the flow features with and without casing treatment was performed and the results are discussed against 3D viscous computational predictions. The casing treatment did not present any improvement of the compressor stall margin but no significant performance degradation was observed either. The CFD predictions showed a good agreement with the measurements and their analysis supported the experimental results.

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3D Unsteady Flow and Forces in Centrifugal Impellers With Circumferential Distortion of the Outlet Static Pressure

Volume 1: Turbomachinery ◽

10.1115/95-gt-033 ◽

1995 ◽

Cited By ~ 4

Author(s):

Antonios Fatsis ◽

Stephane Pierret ◽

René Van den Braembussche

Keyword(s):

Flow Field ◽

Unsteady Flow ◽

Parametric Study ◽

Static Pressure ◽

Centrifugal Impeller ◽

Radial Forces ◽

3D Unsteady Flow ◽

Euler Solver ◽

Impeller Geometry ◽

Negligible Influence

This paper describes the numerical investigation of the centrifugal impeller response to downstream static pressure distortions imposed by volutes at off-design operations. An unsteady 3D Euler solver with non-reflecting upstream and downstream boundary conditions and phase-lagged periodicity conditions is used for this purpose. The mechanisms governing the unsteady flow field are analysed. A parametric study shows the influence of the acoustic Strouhal number on the amplitude of the flow perturbations. Radial forces calculated on backward leaned and radial ending centrifugal impellers, show non-negligible influence of the impeller geometry.

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Experimental Investigation of Unsteady Flow in Circumferential Skewed Axial Fans at Off-design Conditions

Journal of Mechanical Engineering ◽

10.3901/jme.2013.04.154 ◽

2013 ◽

Vol 49 (04) ◽

pp. 154

Author(s):

Guangyuan JIN

Keyword(s):

Experimental Investigation ◽

Unsteady Flow ◽

Axial Fans

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Experimental Investigation of the Unsteady Flow Field Downstream of a Counter-Rotating Two-Spool Turbine Rig

Volume 8: Turbomachinery, Parts A, B, and C ◽

10.1115/gt2012-68583 ◽

2012 ◽

Cited By ~ 5

Author(s):

Davide Lengani ◽

Cornelia Santner ◽

Rosario Spataro ◽

Berardo Paradiso ◽

Emil Göttlich

Keyword(s):

Experimental Investigation ◽

Flow Field ◽

Unsteady Flow ◽

Fast Response ◽

Secondary Flows ◽

Operating Conditions ◽

Pressure Probe ◽

Time Resolved ◽

Flow Angle ◽

Aerodynamic Pressure

The paper presents an experimental investigation of the unsteady flow field in the two-spool counter-rotating transonic turbine at Graz University of Technology. The test setup consists of a high pressure (HP) stage, a diffusing mid turbine frame with turning struts (TMTF) and a shrouded low pressure (LP) rotor. The two rotors are mounted on mechanically independent shafts in order to provide engine-representative operating conditions. The rig was designed in cooperation with MTU Aero Engines and Volvo Aero within the EU project DREAM (ValiDation of Radical Engine Architecture SysteMs). A two-sensor fast response aerodynamic pressure probe (2S-FRAP) has been employed to provide time-resolved aerodynamic area traverses downstream of the LP turbine. Such measurement allows estimating the total deterministic unsteadiness transported through the duct. In particular, it has been possible to isolate the structures induced by each rotor by means of the encoders mounted on the two shafts. A global ensemble averaged field, which takes into account the rotor-rotor interactions, is also provided. The time resolved distributions of the flow quantities are then discussed in details. The perturbations due to the HP rotor in terms of velocity and flow angle are negligible in this downstream plane. Indeed, the largest fluctuations of velocity are due to the TMTF-LP rotor interaction, they occur in the wake and secondary flows of the TMTF. Large fluctuations of static and total pressure are instead due to both rotors to the same extent.

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Experimental investigation of gradually-varied unsteady flow passed a circular pile

Coastal Engineering ◽

10.1016/j.coastaleng.2021.103926 ◽

2021 ◽

pp. 103926

Author(s):

Mehrnoush Kohandel Gargari ◽

V.S. Ozgur Kirca ◽

Oral Yagci

Keyword(s):

Experimental Investigation ◽

Unsteady Flow

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Modal characteristics and fluid–structure interaction vibration response of submerged impeller

Journal of Vibration and Control ◽

10.1177/10775463211003695 ◽

2021 ◽

pp. 107754632110036

Author(s):

Shihui Huo ◽

Hong Huang ◽

Daoqiong Huang ◽

Zhanyi Liu ◽

Hui Chen

Keyword(s):

Flow Field ◽

Unsteady Flow ◽

Damping Ratio ◽

Pure Water ◽

Vibration Response ◽

Modal Identification ◽

Liquid Oxygen ◽

Modal Characteristics ◽

Oxygen Pump ◽

Turbo Pump

Turbo pump is one of the elements with the most complex flow of liquid rocket engine, and as an important component of turbo pump, an impeller is the weak point affecting its reliability. In this study, a noncontact modal characteristic identification technique was proposed for the liquid oxygen pump impeller. Modal characteristics of the impeller under three different submerged media, air, pure water, and brine with same density as liquid oxygen, were tested based on the noncontact modal identification technology. Submersion state directly affects the modal frequencies and damping ratio. The transient vibration response characteristics of the impeller excited by the unsteady flow field was achieved combining with unsteady flow field analysis and transient dynamic analysis in the whole flow passage of the liquid oxygen pump. Vibration responses at different positions of the impeller show 10X and 20X frequencies, and the amplitude at the root of short blade is significant, which needs to be paid more attention in structural design and fatigue evaluation.

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