Recent Applications of Particle Image Velocimetry to Flow Research in Thermal Turbomachinery

Woisetschläger, Jakob; Göttlich, Emil

doi:10.1007/978-3-540-73528-1_16

Cited by 16 publications

(10 citation statements)

References 80 publications

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“…For a narrower field of view and/or reduced spatial resolution, this same setup can be used with a camera frame rate of 200 kHz to produce PIV data up to 100 kHz. PETAL's custom-built burst-mode laser systems [9] have successfully produced PIV data up to 1 MHz [10] in other experiments. With the region of interest being in the middle of the vane passage, there are no measurements from physical instruments such as hot wire anemometers or pitot-static probes that can be used for direct comparison with the PIV results.…”

Section: Experimental Methodologymentioning

confidence: 99%

“…A comprehensive review of recent PIV measurements in rotating turbomachinery applications was performed by Woisetschläger and Göttlich [9], with a special focus on the facilities at Graz University of Technology and at German Aerospace Center DLR. The transonic test turbine facility at Graz University features 24 stator and 36 rotor blades rotating at 10,600 rpm, while the centrifugal compressor at German Aerospace DLR features 13 main and 13 splitter blades rotating at up to 50,000 rpm.…”

Section: Review Of Previous Experimentationmentioning

confidence: 99%

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Particle Image Velocimetry in a High-Pressure Turbine Stage at Aerodynamically Engine Representative Conditions

Inman

Cuadrado

Andreoli

et al. 2021

Journal of Engineering for Gas Turbines and Power

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Particle Image Velocimetry (PIV) is a well-established technique for determining the flow direction and velocity magnitude of complex flows. This paper presents a methodology for executing this non-intrusive measurement technique to study a scaled-up turbine vane geometry within an annular cascade at engine-relevant conditions. Custom optical tools such as laser delivery probes and imaging inserts were manufactured to mitigate the difficult optical access of the test section and perform planar PIV. With the use of a burst-mode Nd: YAG laser and Photron FASTCAM camera, the frame straddling technique is implemented to enable short time intervals for the collection of image pairs and velocity fields at 10 kHz. Furthermore, custom image processing tools were developed to optimize the contrast and intensity balance of each image pair to maximize particle number and uniformity, while removing scattering and background noise. The pre-processing strategies significantly improve the vector yield under challenging alignment, seeding, and illumination conditions. With the optical and software tools developed, planar PIV was conducted in the passage of a high-pressure stator row, at mid-span, in an annular cascade. Different Mach and Reynolds number operating conditions were achieved by modifying the temperature and mass flow. With careful spatial calibration, the resultant velocity vector fields are compared with Reynolds Averaged Navier Stokes (RANS) simulations of the vane passage with the same geometry and flow conditions. Uncertainty analysis of the experimental results is also presented and discussed, along with prospects for further improvements.

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Section: Experimental Methodologymentioning

confidence: 99%

Section: Review Of Previous Experimentationmentioning

confidence: 99%

Particle Image Velocimetry in a High-Pressure Turbine Stage at Aerodynamically Engine Representative Conditions

Inman

Cuadrado

Andreoli

et al. 2021

Journal of Engineering for Gas Turbines and Power

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show abstract

“…The first derivative of the position with respect to the time is the velocity, which is of outstanding importance for instance in the understanding and characterization of fluid mechanics including the riddle of turbulence [8]. Current reviews for micro fluidic flow measurements [9] and meso-and macroscopic optical flow velocity field measurements based on Mie scattering [10] illustrate the huge application potential, e.g., for aerodynamic studies in turbomachinery [11,12], for thermoacoustic phenomena in flame flows [13,14], for transient two-phase flow phenomena in fast fuel injections shorter than one millisecond [15,16]. Further flows of interest are large scale flows such as occurring on the sun surface with velocity fluctuations up to ±1000 m/s [17] or small scale flows in micro channels in the order of mm/s [18].…”

Section: Motivationmentioning

confidence: 99%

Limiting Uncertainty Relations in Laser-Based Measurements of Position and Velocity Due to Quantum Shot Noise

Fischer

2019

Entropy

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With the ongoing progress of optoelectronic components, laser-based measurement systems allow measurements of position as well as displacement, strain and velocity with unbeatable speed and low measurement uncertainty. The performance limit is often studied for a single measurement setup, but a fundamental comparison of different measurement principles with respect to the ultimate limit due to quantum shot noise is rare. For this purpose, the Cramér-Rao bound is described as a universal information theoretic tool to calculate the minimal achievable measurement uncertainty for different measurement techniques, and a review of the respective lower bounds for laser-based measurements of position, displacement, strain and velocity at particles and surfaces is presented. As a result, the calculated Cramér-Rao bounds of different measurement principles have similar forms for each measurand including an indirect proportionality with respect to the number of photons and, in case of the position measurement for instance, the wave number squared. Furthermore, an uncertainty principle between the position uncertainty and the wave vector uncertainty was identified, i.e., the measurement uncertainty is minimized by maximizing the wave vector uncertainty. Additionally, physically complementary measurement approaches such as interferometry and time-of-flight positions measurements as well as time-of-flight and Doppler particle velocity measurements are shown to attain the same fundamental limit. Since most of the laser-based measurements perform similar with respect to the quantum shot noise, the realized measurement systems behave differently only due to the available optoelectronic components for the concrete measurement task.

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“…Woisetschläger and Göttlich [28] provide an in-depth discussion on the application of PIV to the study of turbomachinery fluid dynamics. CO2 PLIF and VV require the same basic configuration as standard PIV techniques: a system for seeding the flow with trace GTP-19-1552 Sangan particles; a means of introducing the laser to the test region; and windows to provide a view of the illuminated flow to the cameras.…”

Section: Optical Measurement Techniquesmentioning

confidence: 99%

An Advanced Single-Stage Turbine Facility for Investigating Nonaxisymmetric Contoured Endwalls in the Presence of Purge Flow

Jones

Pountney

Cleton

et al. 2019

Journal of Engineering for Gas Turbines and Power

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In modern gas turbines, endwall contouring (EWC) is employed to modify the static pressure field downstream of the vanes and minimize the growth of secondary flow structures developed in the blade passage. Purge flow (or egress) from the upstream rim-seal interferes with the mainstream flow, adding to the loss generated in the rotor. Despite this, EWC is typically designed without consideration of mainstream–egress interactions. The performance gains offered by EWC can be reduced, or in the limit eliminated, when purge air is considered. In addition, EWC can result in a reduction in sealing effectiveness across the rim seal. Consequently, industry is pursuing a combined design approach that encompasses the rim-seal, seal-clearance profile, and EWC on the rotor endwall. This paper presents the design of and preliminary results from a new single-stage axial turbine facility developed to investigate the fundamental fluid dynamics of egress–mainstream flow interactions. To the authors' knowledge, this is the only test facility in the world capable of investigating the interaction effects between cavity flows, rim seals, and EWC. The design of optical measurement capabilities for future studies, employing volumetric velocimetry (VV) and planar laser-induced fluorescence (PLIF), is also presented. The fluid-dynamically scaled rig operates at benign pressures and temperatures suited to these techniques and is modular. The facility enables expedient interchange of EWC (integrated into the rotor bling), blade-fillet and rim-seal geometries. The measurements presented in this paper include: gas concentration effectiveness and swirl measurements on the stator wall and in the wheel-space core; pressure distributions around the nozzle guide vanes (NGV) at three different spanwise locations; pitchwise static pressure distributions downstream of the NGV at four axial locations on the stator platform.

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Recent Applications of Particle Image Velocimetry to Flow Research in Thermal Turbomachinery

Cited by 16 publications

References 80 publications

Particle Image Velocimetry in a High-Pressure Turbine Stage at Aerodynamically Engine Representative Conditions

Particle Image Velocimetry in a High-Pressure Turbine Stage at Aerodynamically Engine Representative Conditions

Limiting Uncertainty Relations in Laser-Based Measurements of Position and Velocity Due to Quantum Shot Noise

An Advanced Single-Stage Turbine Facility for Investigating Nonaxisymmetric Contoured Endwalls in the Presence of Purge Flow

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