Turbulence Field Measurements at the Exit of a Combustor Simulator Dedicated to Hot Streaks Generation

2015 ◽  
Author(s):  
Tommaso Bacci ◽  
Bruno Facchini ◽  
Alessio Picchi ◽  
Lorenzo Tarchi ◽  
Charlie Koupper ◽  
...  
Keyword(s):  
Measurement Techniques ◽  
Field Measurements ◽  
Time Correlation ◽  
Test Point ◽  
Lean Burn ◽  
Experimental Campaign ◽  
Turbulence Decay ◽  
Flow Turbulence ◽  
University Of Florence ◽  
Real Scale

In order to deepen the knowledge of the interaction between modern lean burn combustors and high pressure turbines, a real scale annular three sector combustor simulator has been assembled at University of Florence, with the goal of investigating and characterizing the generated flow field. To generate hot streaks and simulate lean burn combustors behavior, the rig is equipped with axial swirlers, fed by main air flow that is heated up to 531 K, and liners with effusion cooling holes that are fed by air at ambient temperature. The three sector configuration is used to reproduce the periodicity on the central sector. Ducts of different lengths have been mounted on the swirlers to reduce the interaction of the mainstream with the coolant. Such configurations have been tested, using different measurement techniques, in order to highlight the differences in the resulting flow fields. The work presented in this paper shows the experimental campaign carried out to investigate the flow turbulence at combustor exit, in isothermal conditions, by means of hot wire anemometry. The goal has been achieved by investigating each test point twice, using an automatic traverse system equipped, in turn, with two split-fiber probes, that allow to measure the velocity components on two planes orthogonal to each other. A method for the time correlation of the signals obtained by the two different tests has been used. In order to analyse the turbulence decay towards the vanes location, such measurements have been performed on two different planes: one located in correspondence of the combustor exit and the further one placed downstream, in the virtual location of the vanes leading edges.

Flowfield and Temperature Profiles Measurements on a Combustor Simulator Dedicated to Hot Streaks Generation

2015 ◽  
Author(s):  
Tommaso Bacci ◽  
Gianluca Caciolli ◽  
Bruno Facchini ◽  
Lorenzo Tarchi ◽  
Charlie Koupper ◽  
...  
Keyword(s):  
High Pressure ◽  
Flow Field ◽  
Measurement Techniques ◽  
Symmetry Plane ◽  
Operating Conditions ◽  
Pressure Probe ◽  
Lean Burn ◽  
Experimental Database ◽  
Set Up ◽  
University Of Florence

In order to deepen the knowledge of the interaction between modern lean burn combustors and high pressure turbines, a real scale annular three sector combustor simulator has been assembled at University of Florence, with the goal of investigating and characterizing the generated aerothermal field and the hot streaks transport between combustor exit and the high pressure vanes location. To generate hot streaks and simulate lean burn combustors behavior, the rig is equipped with axial swirlers, fed by main air flow that is heated up to 531 K, and liners with effusion cooling holes that are fed by air at ambient temperature. The three sector configuration is used to reproduce the periodicity on the central sector and to allow to perform measurements inside the chamber, through the lateral walls. Ducts of different length have been mounted on the swirlers, preserving the hot mainflow from the interaction with coolant. Such configurations, together with the one without ducts, have been tested, using different measurement techniques, in order to highlight the differences in the resulting flow fields. First of all, isothermal PIV measurements have been performed on the combustion chamber symmetry plane, to highlight the mixing phenomena between the mainflow and cooling flows. Then a detailed investigation of the mean aerothermal field at combustor exit has been carried out, for nominal operating conditions, by means of a five hole pressure probe provided with a thermocouple, installed on an automatic traverse system. With the aim of analyzing the hot streaks transport and the flow field modification towards the vanes location, such measurements have been performed on two different planes: one located in correspondence of the combustor exit and the further one placed downstream, in the virtual location of the vanes leading edges. Therefore, an experimental database, describing the evolution of the flow field in a combustor simulator with typical traits of modern lean burn chambers, for different injector geometries, has been set up.

Flow Field and Hot Streak Migration Through a High Pressure Cooled Vanes With Representative Lean Burn Combustor Outflow

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Tommaso Bacci ◽  
Tommaso Lenzi ◽  
Alessio Picchi ◽  
Lorenzo Mazzei ◽  
Bruno Facchini
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Flow Field ◽  
Fuel Injection ◽  
Leading Edge ◽  
Flame Stabilization ◽  
Lean Burn ◽  
Aero Engine ◽  
University Of Florence ◽  
Hot Streak

Modern lean burn aero-engine combustors make use of relevant swirl degrees for flame stabilization. Moreover, important temperature distortions are generated, in tangential and radial directions, due to discrete fuel injection and liner cooling flows respectively. At the same time, more efficient devices are employed for liner cooling and a less intense mixing with the mainstream occurs. As a result, aggressive swirl fields, high turbulence intensities, and strong hot streaks are achieved at the turbine inlet. In order to understand combustor-turbine flow field interactions, it is mandatory to collect reliable experimental data at representative flow conditions. While the separated effects of temperature, swirl, and turbulence on the first turbine stage have been widely investigated, reduced experimental data is available when it comes to consider all these factors together.In this perspective, an annular three-sector combustor simulator with fully cooled high pressure vanes has been designed and installed at the THT Lab of University of Florence. The test rig is equipped with three axial swirlers, effusion cooled liners, and six film cooled high pressure vanes passages, for a vortex-to-vane count ratio of 1:2. The relative clocking position between swirlers and vanes has been chosen in order to have the leading edge of the central NGV aligned with the central swirler. In order to generate representative conditions, a heated mainstream passes though the axial swirlers of the combustor simulator, while the effusion cooled liners are fed by air at ambient temperature. The resulting flow field exiting from the combustor simulator and approaching the cooled vane can be considered representative of a modern Lean Burn aero engine combustor with swirl angles above ±50 deg, turbulence intensities up to about 28% and maximum-to-minimum temperature ratio of about 1.25. With the final aim of investigating the hot streaks evolution through the cooled high pressure vane, the mean aerothermal field (temperature, pressure, and velocity fields) has been evaluated by means of a five-hole probe equipped with a thermocouple and traversed upstream and downstream of the NGV cascade.

scholarly journals Numerical simulation of drifting snow: erosion and deposition models

1998 ◽  
Vol 26 ◽  
pp. 191-196 ◽  
Author(s):  
Mohamed Naaim ◽  
Florence Naaim-Bouvet ◽  
Hugo Martinez
Keyword(s):  
Mass Exchange ◽  
Field Measurements ◽  
Numerical Results ◽  
Back Reaction ◽  
Erosion And Deposition ◽  
Deposition Model ◽  
Drifting Snow ◽  
Snow Fence ◽  
Flow Turbulence ◽  
Deposition Models

Earlier works on numerical modelling are analysed. Anderson and Haff (1991) proposed a model using the “splash” function which was defined for cohesionless sand. The Uematsu and others (1989, 1991) and Liston and others (1993,1994) approaches are based on fluid-mechanics conservation laws where the snow is transported and diffused by the air flow. These models consider the saltation layer as a boundary condition.For the flow, and for the suspension, we adopt the same model as that of Uematsu and Liston. For mass exchange between the flow and snow surface, we have developed an erosion–deposition model where mass exchange is defined in relation to flow turbulence, threshold-friction velocity and snow concentration. Our snow-erosion model was calibrated using Takeuchi's(1980) field measurements. The deposition model was tested by comparing numerical results with wind-tunnel ones, for sawdust-accumulation windward and leeward of a solid snow fence with a bottom gap. The numerical results obtained are close to the experimental results. The main results of the various sensitivity experiments are: the leeward accumulation is very sensitive to the ratio (u*/u*t) (it appears for (u*/u*t) close to 1 and disappears for (u*/u*t) > 1.2), the global accumulation produced by the fence increases as (u*/u*t) decreases and the back reaction of particles on turbulence extends slightly the windward accumulation.

Adiabatic Effectiveness and Flow Field Measurements in a Realistic Effusion Cooled Lean Burn Combustor

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Antonio Andreini ◽  
Riccardo Becchi ◽  
Bruno Facchini ◽  
Lorenzo Mazzei ◽  
Alessio Picchi ◽  
...  
Keyword(s):  
Flow Field ◽  
Field Measurements ◽  
Injection System ◽  
Wall Region ◽  
Test Model ◽  
Nox Emissions ◽  
Lean Burn ◽  
Experimental Apparatus ◽  
Adiabatic Effectiveness ◽  
The Impact

Over the last ten years, there have been significant technological advances toward the reduction of NOx emissions from civil aircraft engines, strongly aimed at meeting stricter and stricter legislation requirements. Nowadays, the most prominent way to meet the target of reducing NOx emissions in modern combustors is represented by lean burn swirl stabilized technology. The high amount of air admitted through a lean burn injection system is characterized by very complex flow structures such as recirculations, vortex breakdown, and precessing vortex core (PVC) that may deeply interact in the near wall region of the combustor liner. This interaction makes challenging the estimation of film cooling distribution, commonly generated by slot and effusion systems. The main purpose of the present work is the characterization of the flow field and the adiabatic effectiveness due to the interaction of swirling flow, generated by real geometry injectors, and a liner cooling scheme made up of a slot injection and an effusion array. The experimental apparatus has been developed within EU project LEMCOTEC (low emissions core-engine technologies) and consists of a nonreactive three-sectors planar rig; the test model is characterized by a complete cooling system and three swirlers, replicating the geometry of a GE Avio PERM (partially evaporated and rapid mixing) injector technology. Flow field measurements have been performed by means of a standard 2D PIV (particle image velocimetry) technique, while adiabatic effectiveness maps have been obtained using PSP (pressure sensitive paint) technique. PIV results show the effect of coolant injection in the corner vortex region, while the PSP measurements highlight the impact of swirled flow on the liner film protection separating the contribution of slot and effusion flows. Furthermore, an additional analysis, exploiting experimental results in terms of heat transfer coefficient, has been performed to estimate the net heat flux reduction (NHFR) on the cooled test plate.

scholarly journals Nozzles, turbulence, and jet noise prediction

2018 ◽  
Vol 860 ◽  
pp. 1-4 ◽  
Author(s):  
Jonathan B. Freund
Keyword(s):  
Prediction Accuracy ◽  
Jet Noise ◽  
Sound Field ◽  
Field Measurements ◽  
Detailed Comparison ◽  
Large Eddy Simulations ◽  
Noise Prediction ◽  
Large Eddy ◽  
Modelling Procedure ◽  
Flow Turbulence

Jet noise prediction is notoriously challenging because only subtle features of the flow turbulence radiate sound. The article by Brès et al. (J. Fluid Mech., vol. 851, 2018, pp. 83–124) shows that a well-constructed modelling procedure for the nozzle turbulence can provide unprecedented sub-dB prediction accuracy with modest-scale large-eddy simulations, as confirmed by detailed comparison with turbulence and sound-field measurements. This both illuminates the essential mechanisms of the flow and facilitates prediction for engineering design.

scholarly journals Nondestructive Testing of Ceramic Hip Joint Implants with Laser Spot Thermography

2017 ◽  
Vol 62 (4) ◽  
pp. 2133-2139
Author(s):  
J. Roemer ◽  
L. Pieczonka ◽  
M. Juszczyk ◽  
T. Uhl
Keyword(s):  
Damage Detection ◽  
Measurement Techniques ◽  
Infrared Camera ◽  
Field Measurements ◽  
Ceramic Materials ◽  
Test Sample ◽  
Theoretical Background ◽  
Laser Spot ◽  
Signal Acquisition ◽  
Full Field

AbstractThe paper presents an application of laser spot thermography for damage detection in ceramic samples with surface breaking cracks. The measurement technique is an active thermographic approach based on an external heat delivery to a test sample, by means of a laser pulse, and signal acquisition by an infrared camera. Damage detection is based on the analysis of surface temperature distribution near the exciting laser spot. The technique is nondestructive, non-contact and allows for full-field measurements. Surface breaking cracks are a very common type of damage in ceramic materials that are introduced in the manufacturing process or during the service period. This paper briefly discusses theoretical background of laser spot thermography, describes the experimental test rig and signal processing methods involved. Damage detection results obtained with laser spot thermography are compared with reference measurements obtained with vibrothermography. This is a different modality of active thermography, that has been previously proven effective for this type of damage. We demonstrate that both measurement techniques can be effectively used for damage detection and quality control applications of ceramic materials.

Optical Methods for Studies of Self-Excited Oscillations and the Effect of Dampers in a High Pressure Single Sector Combustor

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
U. Meier ◽  
L. Lange ◽  
J. Heinze ◽  
C. Hassa ◽  
S. Sadig ◽  
...  
Keyword(s):  
High Pressure ◽  
Heat Release ◽  
Optical Measurement ◽  
Measurement Techniques ◽  
Operating Conditions ◽  
Optical Methods ◽  
Pressure Oscillations ◽  
Lean Burn ◽  
Reaction Zones ◽  
Injector Flows

Self-excited periodic instabilities in a staged lean burn injector could be forced by operating the combustor at off-design conditions. These pressure oscillations were studied in a high pressure single sector combustor with optical access. Two damper configurations were installed and tested with respect to their damping efficiency in relation to the configuration without dampers. For a variety of test conditions, derived from a part load case, time traces of pressure in the combustor were measured, and amplitudes were derived from their Fourier transformation. These measurements were performed for several combinations of the operating parameters, i.e., injector pressure drop, air/fuel ratio (AFR), pilot/main fuel split, and preheat temperature. These tests “ranked” the respective damper configurations and their individual efficiency with respect to the configuration without dampers. Although a general trend could be observed, the ranking was not strictly consistent for all operating conditions. For several test cases, preferably with pronounced self-excited pressure oscillations, phase-resolved planar optical measurement techniques were applied to investigate the change of spatial structures of fuel, reaction zones, and temperature distributions over a period of an oscillation. A pulsating motion was detected for both pilot and main flame, driven by a pulsating transport of the liquid fuel. This pulsation, in turn, is caused by a fluctuating air velocity, in connection with a prefilming airblast type atomizer. A phase shift between pilot and main injector heat release was observed, corresponding to a shift of fuel penetration. Local Rayleigh indices were calculated qualitatively, based on phase-resolved OH chemiluminescence used as marker for heat release, and corresponding pressure values. This identified regions, where a local amplification of pressure oscillations occurred. These regions were largely identical to the reaction regions of pilot and main injector, whereas the recirculation zone between the injector flows was found to exhibit a damping effect.

scholarly journals Simultaneous PIV and DIC Measurements in a Towing Tank Environment with a Flexible Hydrofoil

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Gunnar Jacobi ◽  
Alex Nila
Keyword(s):  
Flow Field ◽  
Accurate Determination ◽  
Measurement Techniques ◽  
Weight Ratio ◽  
Field Measurements ◽  
Tip Vortex ◽  
Vortex Center ◽  
Phase Lag ◽  
Maritime Industry ◽  
Wing Tip

Due to their good mechanical properties composite materials are increasingly applied for the construction of lifting surfaces in the maritime industry. However, besides improving the strength to weight ratio of a structure, the anisotropic material properties can also exhibit bend-twist coupling, when exposed to higher loads. In order to experimentally measure the fluid structure interaction, the object of investigation needs to exposed to the same fluid loadings, as it would experience during operation. To investigate the possibility to obtain simultaneous deformation and flow field measurements in a large hydrodynamic testing facility simultaneous PIV and DIC measurements are performed to obtain the deformation of a flexible NACA 0008 hydrofoil and to measure the flow field in the wing tip region. For the assessment of the performance of the methods two scenarios are presented including tests in stationary conditions with constant angles of attack and forced plunging oscillations. The calibration of both measurement systems is done independently and the wing tip, visible in the PIV images, is used for triangulation to find the position of the wing within the PIV coordinate system. The combination of both measurement techniques allows for an accurate determination of tip vortex center positions with respect to the deformed wing and their evolution downstream of the wing. During forced plunging motions, the phase lag of the wing tip and the influence on the wing tip vortex is observed.

scholarly journals An Experimental Investigation on the Impact of Duplexing and Beamforming Techniques in Field Measurements of 5G Signals

Electronics ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 223 ◽  
Author(s):  
Daniele Franci ◽  
Stefano Coltellacci ◽  
Enrico Grillo ◽  
Settimio Pavoncello ◽  
Tommaso Aureli ◽  
...  
Keyword(s):  
New Technology ◽  
Measurement Techniques ◽  
Multiple Input Multiple Output ◽  
Mobile Network ◽  
Field Measurements ◽  
Total Power ◽  
Exposure Limits ◽  
Field Exposure ◽  
Starting Point ◽  
The Impact

The fifth generation mobile network introduces dramatic improvements with respect to the previous technologies. Features such as variable numerology, bandwidth parts, massive Multiple Input Multiple Output (MIMO) and Time Division Duplex (TDD) will extend the capabilities of the 5G wireless systems and, at the same time, will influence the measurement techniques used to assess the compliance with general public electromagnetic field exposure limits. In this study, a heterogeneous set of 5G signals is investigated with the aim of establishing an effective measurement technique suitable for the new technology. Following an experimental approach based on both modulation and zero span analysis, some important characteristics of the 5G system are highlighted and extensively discussed, and experimental procedures for estimating factors associated to TDD (F T D C factor) and beam sweeping (R factor), to be used in the extrapolation formulas, are presented. The results of this study represent a starting point for future investigations on effective methods to estimate both the instant maximum power and the total power transmitted during a 5G radio frame.

scholarly journals JSI TRIGA neutron and gamma field characterization by TLD measurements

2020 ◽  
Vol 225 ◽  
pp. 04034
Author(s):  
Klemen Ambrožič ◽  
Klaudia Malik ◽  
Barkara Obryk ◽  
Luka Snoj
Keyword(s):  
Radiation Field ◽  
Radiation Effects ◽  
Nuclear Reactor ◽  
Measurement Techniques ◽  
Field Measurements ◽  
Reactor Irradiation ◽  
Fission Chamber ◽  
Start Up ◽  
Gamma Field ◽  
Irradiation Facilities

A well characterized radiation field inside a research nuclear reactor irradiation facilities enables precise qualification of radiation effects to the irradiated samples such as nuclear heating or changes in their electrical or material properties. To support the increased utilization of the JSI TRIGA reactor irradiation facilities in the past few years mainly on account of testing novel detector designs, electronic components and material samples, we are working on increasing the neutron and gamma field characterization accuracy using various modeling and measurement techniques. In this paper we present the dose field measurements using thermo-luminescent detectors (TLD’s) with different sensitivities neutron and gamma sensitivities, along with multiple ionization and fission chamber. Experiment was performed in several steps from reactor start-up, steady operation and a rapid shutdown, during which the ionization and fission chamber signals were acquires continuously, while the TLD’s were being irradiated at different stages during reactor operation and after shutdown, to also capture response to delayed neutron and gamma field. The results presented in this paper serve for validation of JSI designed JSIR2S code for delayed radiation field determination, initial results of its application on the JSI TRIGA TLD measurements will also be presented.

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