3-Component Doppler laser-two-focus velocimetry applied to a transonic centrifugal compressor

Förster, Wolfgang; Karpinsky, G.; Krain, H.; Röhle, I.; Schodl, R.

doi:10.1007/978-3-662-08263-8_4

Cited by 11 publications

(7 citation statements)

References 3 publications

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“…The improvement of the flow field inside the impeller, which was predicted to be more homogeneous, was successfully verified by means of L2F measurements (Förster et al 2000, Krain et al 2001and Krain 2003. For investigation of the flow phenomena in the diffuser region PIV was chosen, as it provides all attributes needed to support and validate the CFD investigations of the compressor flow, which are performed in parallel to the experimental part of the research program.…”

Section: Introductionmentioning

confidence: 91%

Application of particle image velocimetry to a transonic centrifugal compressor

et al. 2007

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A variety of measurement techniques have been applied to investigate the flow phenomena occurring in advanced turbomachinery components. In an ongoing research project the performance and internal flow field of a high pressure ratio centrifugal compressor is being investigated. Based on the results obtained the compressor was redesigned and resulted in an improved impeller and diffuser. The stage was designed for a total pressure ratio of 6:1 and a mass flow rate of 2.55 kg/s, the corresponding rotor tip speed was 586 m/s, resulting in transonic flow conditions at the inlet of the diffuser vane passage at a static temperature of 260°C. The improvement of the impeller flow and the broadening of the stable operating range was predicted by CFD and successfully verified by means of laser-2-focus (L2F) measurements.Current activities in the research program involve the use of particle image velocimetry (PIV) to analyze and further improve the understanding of the complex flow phenomena inside the vaned diffuser. The study includes phase-resolved measurements of the flow inside a diffuser vane passage with respect to the impeller blade position. Both, instantaneous and phase-averaged velocity fields will be presented.Optical access is given via a quartz glass window, which was manufactured to match the 3-D contour of the diffuser casing in order to minimize disturbance of the near-wall flow. An adjustable periscope light sheet probe was specifically designed for this application and delivered the laser light sheet (LLS) to the desired vane span positions for the flow field investigation. The periscope probe was purged with compressed air during operation for cooling and to protect the open outlet of the probe from seeding particle deposits.The flow field results obtained with PIV will be used for validation of the CFD calculations. Based on this approach a better understanding of the complex flow characteristics is expected, which will finally result in a further improvement of the compressor performance.

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Section: Introductionmentioning

confidence: 91%

Application of particle image velocimetry to a transonic centrifugal compressor

et al. 2007

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“…In short, the laser-2-focus measurement method is based on a time-of-flight measurement of a particle captured between the focuses of two laser beams [22][23][24][25][26][27][28]. The velocity is determined by means of the distance between the two foci and the corresponding time-of-flight.…”

Section: Laser-2-focus (L2f)mentioning

confidence: 99%

Characterization of SRM plumes with alumina particulate in subscale testing

et al. 2020

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The current paper provides an outline and first results of the ESA-EMAP project. This project pursues activities regarding the experimental modeling of alumina particulates in solid boosters (EMAP). The issue regards the particles residing in the atmosphere after the passage of a launch vehicle with solid rocket propulsion, which might contribute to local and overall ozone depletion. The question is to what extent since the particle size distribution left behind is essentially unclear. For this reason, the ESA-EMAP investigations focus on the characterization of the solid exhaust plume properties for well-defined combustion chamber conditions. Thus, details of the rocket motor assembly, of the developed solid propellant grains, and of first measurement results are provided. The paper presents technical findings concerning the rocket motors and reveals aspects to the feasibility of the applied measurement techniques.

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“…For narrow optical accesses, which means low numerical apertures, the measurement of all three velocity components with a single principle is only achievable with additional observation or light incidence directions. If the additional optical access is not available or undesired, then the combination of both principles allows one to obtain measurements of all three velocity components with only one light incidence direction and one observation direction [34][35][36]. A further example of a beneficial combination of Doppler and time-of-flight principles is reported in [37], where a time-of-flight principle is used to resolve the velocity field image, but with a lower spatial and temporal resolution than the simultaneous single point Doppler measurement.…”

Section: Scattered Light Evaluationmentioning

confidence: 99%

“…This measurement technique is known as laser-2-focus anemometry (L2F). The approach was later extended for 2c and 3c measurements, but it remained a 0d measurement technique to date [34,99].…”

Section: Time Measurementmentioning

confidence: 99%

Imaging Flow Velocimetry with Laser Mie Scattering

Fischer

2017

Applied Sciences

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Abstract:Imaging flow velocity measurements are essential for the investigation of unsteady complex flow phenomena, e.g., in turbomachines, injectors and combustors. The direct optical measurement on fluid molecules is possible with laser Rayleigh scattering and the Doppler effect. However, the small scattering cross-section results in a low signal to noise ratio, which hinders time-resolved measurements of the flow field. For this reason, the signal to noise ratio is increased by using laser Mie scattering on micrometer-sized particles that follow the flow with negligible slip. Finally, the ongoing development of powerful lasers and fast, sensitive cameras has boosted the performance of several imaging methods for flow velocimetry. The article describes the different flow measurement principles, as well as the fundamental physical measurement limits. Furthermore, the evolution to an imaging technique is outlined for each measurement principle by reviewing recent advances and applications. As a result, the progress, the challenges and the perspectives for high-speed imaging flow velocimetry are considered.

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3-Component Doppler laser-two-focus velocimetry applied to a transonic centrifugal compressor

Cited by 11 publications

References 3 publications

Application of particle image velocimetry to a transonic centrifugal compressor

Application of particle image velocimetry to a transonic centrifugal compressor

Characterization of SRM plumes with alumina particulate in subscale testing

Imaging Flow Velocimetry with Laser Mie Scattering

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