CERES :: Browsing by Author "Migliorini, Matteo"

Browsing by Author "Migliorini, Matteo"

Now showing 1 - 20 of 21

Open Access
2D3C measurement of velocity, pressure and temperature fields in a intake flow of an air turbine by Filtered Rayleigh Sattering (FRS) and validation with LDV and PIV
(International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics, 2024-07-08) Dues, Michael; Dues, Fritz; Melnikov, Sergey; Steinbock, Jonas Johannes; Doll, Ulrich; Röhle, Ingo; Migliorini, Matteo; Zachos, Pavlos
A Filtered Rayleigh Scattering Technique is implemented in two different experimental setups and compared to the established velocity measurement techniques Laser Doppler Anemometry (LDA) and Particle Image Velocimetry (PIV). The Frequency Scanning Filtered Rayleigh Scattering Method employed uses an imagefiber bundle which allows for the simultaneous observation of the flow situation from six independent perspectives, utilizing only one sCMOS camera. A testrig with a nominal diameter of 80 mm was implemented by ILA R&D GmbH. Here measurements with straight pipe flow and a swirl generator were realised, as well as comparisions with LDA. A second experiment utilized Cranfields University’s Complex Intake Facility (CCITF), enabling the simulation of the flow field for an engine intake as observed behind an S-Duct diffuser. The diameter in the measuring plane was 160 mm. Measurements up to a mach number of 0.4 were performed and compared with HighSpeed Stereo-PIV (S-PIV) measurements. Good agreement was achieved in respect to both the absolute magnitude of the velocity measurements as well as to the resolution of complex flow structures. The developed FRS multi-view Setup is able to simultaneously determine the 3D velocity components, the pressure and the temperature on a measurement plane with high resolution and without seeding. After calibration the FRS system yields the pressure and temperature within 3 percent respectively 0.8 percent of the reference values. The measured velocity was within 1-2 m/s of the reference.
Open Access
Advancements on the use of Filtered Rayleigh Scattering (FRS) with machine learning methods for flow distortion in aero-engine intakes
(Elsevier, 2025-01-01) Migliorini, Matteo; Doll, Ulrich; Lawson, Nicholas J.; Melnikov, Sergey M.; Steinbock, Jonas; Dues, Michael; Zachos, Pavlos K.; Röhle, Ingo; MacManus, David G.
In-flight measurements of aerodynamic quantities are a requirement to ensure the correct scaling of Reynolds and Mach number and for the airworthiness certification of an aircraft. The ability to obtain such measurement is subject to several challenges such as instrument installation, environment, type of measurand, and spatial and temporal resolution. Given expected, more frequent use of embedded propulsion systems in the near future, the measurement technology needs to adapt for the characterization of multi-type flow distortion in complex flow, to assess the operability of air-breathing propulsion systems. To meet this increasing demand for high-fidelity experimental data, the Filtered Rayleigh Scattering (FRS) method is identified as a promising technology, as it can provide measurements of pressure, temperature and 3D velocities simultaneously, across a full Aerodynamic Interface Plane (AIP). Τhis work demonstrates the application of a novel FRS instrument, to assess the flow distortion in an S-duct diffuser, in a ground testing facility. A comparison of FRS results with Stereo-Particle Image Velocimetry (S-PIV) measurements reveals good agreement of the out of plane velocities, within 3.3 % at the AIP. Furthermore, the introduction of machine learning methods significantly accelerates the processing of the FRS data by up to 200 times, offering a substantial prospect towards real time data analysis. This study demonstrates the further development of the FRS technique, with the ultimate goal of inlet flow distortion measurements for in-flight environments.
Open Access
An assessment on the unsteady flow distortion generated by an S-duct intake
(AIAA, 2019-08-16) Migliorini, Matteo; Zachos, Pavlos; MacManus, David G.
Closer integration between the fuselage and the propulsion system is expected for futureaircraft toreducefuel consumption, emissions, weight and drag. The use of embedded or partially embedded propulsion systems may require the use of complex intakes. However, thiscanresult in unsteady flow distortion which can adversely affect the propulsion system efficiency and stability. This works assesses the characteristics of the unsteady flow with a view to the potential flow distortion presented to the compression system.Particle image velocimetry is used to measure the flow distortion generated by an S-shaped intake.The time-resolved tracking of the idealized relative incidence angle revealed that most frequent distortion events exhibited90°exposure sector and upto±5°meanrelativeincidence. The imposition of a thicker boundary at the S-duct inlet increased the probability of distortion events that are characterized by a longer exposure sector and higher relative incidence angles.Because of these characteristics, thedistortion caused by the S-duct intake could induce instabilities that are detrimental for the propulsion system performances and stability. Overall, this work proposes a new method to assess thepossible relativeincidence angle on the compressor rotor taking into account the intake flow unsteadiness.
Open Access
Characterization of unsteady distortion events for S-duct intakes under non-uniform inlet conditions
(AIAA, 2023-01-19) Migliorini, Matteo; Zachos, Pavlos K.; MacManus, David
The use of convoluted intakes is expected to grow in novel aircraft configurations as designers seek to integrate more closely the propulsion system with the airframe. Previous research highlighted considerable unsteady flow distortions for S-duct configurations. However, most of the work was limited to the types of flow distortion inherently generated within the duct which reflects a relatively narrow range of aerodynamic conditions. In addition, the conditions of the flow distortion approaching the propulsion system is still not well understood due to the lack of experimental data and methods for unsteady distortion analysis. Recently, a novel analysis method was developed to consider the unsteady flow distortion from the perspective of an envisaged rotor blade through the exploitation of measurements with high-bandwidth Particle Image Velocimetry. In this study, and with this method, the aim is to provide a more advanced classification of unsteady distortion events based on the distribution of incidence on the envisaged rotor blades. This work can provide guidelines for methods to evaluate peak distortion levels under different inlet configurations for intake-engine integration assessments.
Open Access
Data for "SINATRA - Complex intake flow distortion measurements"
(Cranfield University, 2024-09-01) Migliorini, Matteo; Doll, Ulrich; Lawson, Nicholas; Melnikov, Sergey M; Steinbock, Jonas; Dues, Michael; Zachos, Pavos; Roehle, Ingo; MacManus, David
Open Access
Design and optimisation of a Mach 2.5 wind tunnel nozzle
(AIAA, 2023-01-19) Moreno, Miguel; Migliorini, Matteo; Zachos, Pavlos K.; Haslam, Anthony; MacManus, David
The paper presents a methodology for the numerical design and optimization of a distortion-free two-dimensional Mach 2.5 nozzle based on a parametric model. The non-uniformities generated at the Mach wave reflections downstream of the nozzle throat that the Method of Characteristics only partially addresses are minimized. The spatial discretization of the domain is integrated with the boundary layer analysis for fast and robust data processing, especially in the final viscous sublayers in the transition regions within the bulk of the fluid. The flow patterns and corner flows of the supersonic nozzle are assessed via three-dimensional high-fidelity computational fluid dynamics. As a result, a fast workflow for nozzle design to meet prescribed flow quality requirements is herein illustrated.
Open Access
Design of a high-speed intake distortion simulator for propulsion integration research
(AIAA, 2023-01-19) Migliorini, Matteo; Szymanski, Artur; Zachos, Pavlos K.; MacManus, David; Martin, Peter G.
High levels of inlet flow distortion can be a critical aspect in supersonic air induction systems due to the complex spatial nature and notable temporal unsteadiness. This can affect the operability and performance of the propulsion system. Simulation of the intake shock system in a relatively less expensive, lower technology readiness level experimental facility can be an important element to mitigate a significant part of the risk that industrial and certification testing carries. The work described in this paper is part of a programme that aims to develop such a distortion simulation test rig where the capability of advanced non-intrusive measurement techniques would be applied in propulsion integration research. The paper describes the concept, preliminary design and sizing of the working section of the rig, the exhaust system design and the integration of the test model. A brief summary of the rig architecture is provided along with details of the high-pressure system that drives the supersonic flow. The work indicates that careful design of the working section is required to ensure sufficient operating range and representative aerodynamics of the test model. It is also shown that the working section wall interference on the test model is tightly linked with the type and size of the aircraft intake to be tested. Ways to mitigate this interference are herein explored.
Open Access
Dynamic swirl distortion characteristics in S-shaped diffusers using UCNS3D and time-resolved, stereo PIV methods
(AIAA, 2024-01-04) Piovesan, Tommaso; Migliorini, Matteo; Zachos, Pavlos K.; Tsoutsanis, Panagiotis
Embedded propulsion systems are key enablers of future aircraft configurations with expected benefits in reduced environmental impact and enhanced performance. Such propulsion systems are typically integrated with convoluted, complex air induction systems whose dynamic distortion characteristics previously found detrimental to the engine’s stability. Therefore, predictive capability for these complex flows is critical for the design of closely coupled engine – intake architectures. A new High-Order Delayed Detached Eddy Simulation (HODDES) is applied in this work to predict dynamic flow distortion within an S-shaped subsonic diffuser. The aim is to assess the ability of a new solver to predict unsteady and extreme distortion events. The HODDES results have been validated with Time-Resolved Stereo PIV (TR-PIV) data. The analysis shows that the HODDES captures the key mean and unsteady flow characteristics, the spectral content and unsteady distortion descriptor behavior across the Aerodynamic Interface Plane (AIP). Although the predicted mean velocity levels, flow field unsteadiness and range of predicted velocities are notably higher than the ones observed at the experiment by at least 40%, it is suggested that this is an artifact of a discrepancy between the axial planes where the CFD and test data were analyzed. The findings of the work suggest that the HODDES is broadly capturing the dynamic flow fields and with some further effort towards the calibration of its RANS models can be further used to study the integration of closely coupled fan system downstream of air induction systems.
Open Access
Effect of a fan on the unsteady distortion of s-duct intakes
(Association Aeronautique et Astronautique de France (3AF), 2024-04) Migliorini, Matteo; Zachos, Pavlos K.; MacManus, David G.; Giannouloudis, Alexandros
A key requirement for the integration of the propulsion and air induction systems is the assessment of the response of the fan to incoming flow distortion. This is especially crucial for the development of novel aircraft configurations with highly embedded engines. The recent advances in non-intrusive laser-based flow diagnostics increased the experimental capability to measure unsteady flows in convoluted intakes with high resolution in time and space. In the pathway to full-scale intake-engine tests, this work introduces the capability to successfully acquire non-intrusive high resolution flow distortion measurements in close proximity to a high-speed rotating fan. This also quantifies the impact of the fan on the inherent flow distortion of S-duct intakes. The measurements demonstrate that although the effect of the fan on the flow distortion is limited, the rotating blades can cause a local increase of the maximum levels swirl intensity at the blade tip region. Further development work on the ducted fan simulator is needed to operate the fan in the representative range of transonic rotors.
Open Access
Evaluation of extreme value predictions for unsteady flow distortion of aero-engine intakes
(American Society of Mechanical Engineers (ASME), 2024-02-13) Migliorini, Matteo; Zachos, Pavlos K.; MacManus, David G.
Unsteady flow distortion is of interest for the development air-breathing propulsion systems. These stochastic fluctuations can generate incompatibilities between intakes and aero-engines. Observing the extreme flow distortion events during experimental testing is not guaranteed and statistical models such as Extreme Value Theory (EVT) can be used to estimate the occurrence and magnitude of the fluctuations. However, the current industry standard does not provide guidance on how to apply these methods to obtain useful predictions. This work proposes a systematic process to assess the required number of observations for obtaining statistical convergence of the EVT predictions. This is achieved through shuffling of the data samples and relies on the availability of a sufficiently large initial dataset. This can be adopted by gas turbine engineers to evaluate the data recording requirements and to potentially reduce costs associated with experimental programs.
Open Access
The impact of inlet boundary layer thickness on the unsteady aerodynamics of S-duct intakes
(AIAA, 2019-09-16) Migliorini, Matteo; Zachos, Pavlos; MacManus, David G.
The need to reduce aero-engine emissions and direct operating costsis driving the civil aerospace sectortowards considering more integrated propulsion systems. Many of the proposed novel aircraft architectures employ convoluted intakes for either the aero-engine or propulsion system. These intakes are characterized by unsteady distortion that can hinder the performance and operability of the propulsion system. This work assessesthe impact of the inlet boundary layer on the unsteady aerodynamics of an S-duct intake using time-resolved particle image velocimetry at the aerodynamic interface plane.An increase in the boundary layer thickness at the intake inlet increasesthe flow unsteadiness on the swirl angle by up to 40% relativeto the baseline case. The azimuthal orientation of the inlet boundary layer modifies the intensity and topology of the most frequent swirl distortion pattern. For a relatively thick inlet boundary layer, the reduction of the dominant frequencies associated withthe unsteady swirl angle is postulated to be beneficial for the engine stability. Overall, this works gives guidelines for the integration between the intake and the engine across the range of potential inlet operating conditions.
Open Access
Influence of upstream total pressure profiles on S-duct intake flow distortion
(AIAA, 2020-04-15) McLelland, Grant; MacManus, David G.; Zachos, Pavlos K.; Gil-Prieto, Daniel; Migliorini, Matteo
For some embedded engine arrangements, the nature of the inlet distortion is influenced by the boundary layer characteristics at the inlet plane of the intake. This research presents the first quantitative assessment on the influence of inlet boundary layer thickness and asymmetry on the swirl distortion at the exit of an S-shaped intake. Measurements of high spatial and temporal resolution have been acquired at the outlet plane of the S-duct using time-resolved particle image velocimetry. When boundary layer profiles typical of embedded engines are introduced, the characteristic secondary flows at the outlet plane are intensified. Overall, the peak swirl intensity increases by 40% for a boundary layer which is 7 times thicker than the reference case. The unsteady modes of the S-duct remain, although the dominant fluctuations in the flow arise at a frequency 50% lower. When the inlet boundary layer profile becomes asymmetric about the intake centerline the peak swirl events at the hub are reduced by up to 40%. At the tip the peak swirl intensity increases by 29%. The results demonstrate that the effects of inlet boundary layer thickness and asymmetry must be carefully considered as part of engine compatibility tests for complex intakes.
Open Access
Non-intrusive flow diagnostics for unsteady inlet flow distortion measurements in novel aircraft architectures
(Elsevier, 2022-03-09) Doll, Ulrich; Migliorini, Matteo; Baikie, Joni; Zachos, Pavlos K.; Röhle, Ingo; Melnikov, Sergey; Steinbock, Jonas; Dues, Michael; Kapulla, Ralf; MacManus, David G.; Lawson, Nicholas J.
Inlet flow distortion is expected to play a major role in future aircraft architectures where complex air induction systems are required to couple the engine with the airframe. The highly unsteady distortions generated by such intake systems can be detrimental to engine performance and were previously linked with loss of engine stability and potentially catastrophic consequences. During aircraft design, inlet flow distortion is typically evaluated at the aerodynamic interface plane, which is defined as a cross-flow plane located at a specific upstream distance from the engine fan. Industrial testing currently puts more emphasis on steady state distortions despite the fact that, historically, unsteady distortions were acknowledged as equally important. This was partially due to the limitations of intrusive measurement methods to deliver unsteady data of high spatial resolution in combination with their high cost and complexity. However, as the development of aircraft with fuselage-integrated engine concepts progresses, the combination of different types of flow distortions is expected to have a strong impact on the engine’s stability margin. Therefore, the need for novel measurement methods able to meet the anticipated demand for more comprehensive flow information is now more critical than ever. In reviewing the capabilities of various non-intrusive methods for inlet distortion measurements, Filtered Rayleigh Scattering (FRS) is found to have the highest potential for synchronously characterising multiple types of inlet flow distortions, since the method has the proven ability to simultaneously measure velocity, static pressure and temperature fields in challenging experimental environments. The attributes of the FRS method are further analysed aiming to deliver a roadmap for its application on ground-based and in-flight measurement environments.
Open Access
Novel method for evaluating intake unsteady flow distortion
(AIAA, 2021-09-13) Migliorini, Matteo; Zachos, Pavlos K.; MacManus, David G.
Closer integration between the airframe and the propulsion system is expected for future aircraft to reduce fuel consumption, emissions, weight and drag. The use of embedded or partially embedded propulsion systems will require the use of complex intakes. However, this can result in unsteady flow distortion which can adversely affect the propulsion system efficiency and stability. Relative to conventional measurement systems, time-resolved Particle Image Velocimetry provides sufficient spatial and temporal resolution to enable the development of new methods to assess unsteady flow distortion. This work proposes a novel analysis approach to assess the unsteady flow distortion. For an S-duct configuration, the method was successfully used to evaluate the unsteady flow distortion in terms of idealized incidence angle perturbations. This example showed peaks up to ± 30° incidence and a duration equivalent to the passing time of 3 blades. The introduction of a non-uniform total pressure profile at the S-duct inlet increased the probability of peak distortion events with higher magnitude. The method provides an estimate of the likelihood, magnitude and duration of distortion events and is a new way to evaluate flow distortion that could induce instabilities for the propulsion system.
Open Access
S-duct flow distortion with non-uniform inlet conditions
(SAGE, 2022-05-24) Migliorini, Matteo; Zachos, Pavlos K.; MacManus, David G.
Convoluted aero-engine intakes are often required to enable closer integration between engine and airframe. Although the majority of previous research focused on the distortion of S-duct intakes with undistorted inlet conditions, there is a need to investigate the impact of more challenging inlet conditions at which the intake duct is expected to operate. The impact of inlet vortices and total pressure profiles on the inherent unsteady flow distortion of an S-duct intake was assessed with stereo particle image velocimetry. Inlet vortices disrupted the characteristic flow switching mode but had a modest impact on the peak levels and unsteady fluctuations. Non-uniform inlet total pressure profiles increased the peak swirl intensity and its unsteadiness. The frequency of swirl angle fluctuations was sensitive to the azimuthal orientation of the non-uniform total pressure distribution. The modelling of peak distortion with the extreme value theory revealed that although for some inlet configurations the measured peak swirl intensity was similar, the growth rate of the peak values beyond the experimental observations was substantially different and it was related with the measured flow unsteadiness. This highlights the need of unsteady swirl distortion measurements and the use of statistical models to assess the time-invariant peak distortion levels. Overall, the work shows it is vital to include the effect of the inlet flow conditions as it substantially alters the characteristics of the complex intake flow distortion.
Open Access
Seeding-free inlet flow distortion measurement by filtered Rayleigh scattering: diagnostic approach and verification
(AIAA, 2023-01-19) Doll, Ulrich; Kapulla, Ralf; Steinbock, Jonas; Dues, Michael; Migliorini, Matteo; Zachos, Pavlos K.
The expected close coupling between engine and fuselage of future aero-engine architectures will lead to highly distorted inflows at the engine face, presenting a major design risk for efficient and reliable engine operation. In particular, the increase in flow unsteadiness is perceived as a significant challenge. In this context, the Cranfield Complex Intake Test Facility (CCITF) is currently being installed at Cranfield University to reproduce the anticipated level of total pressure and swirl distortion arising from novel, closely coupled airframe-engine configurations. To address the expected demand for much more comprehensive flow field data, it is intended to establish the filtered Rayleigh scattering (FRS) technique for non-intrusive testing of aero-engine intake flows. Unlike the previously used particle image velocimetry (PIV) or Doppler global velocimetry (DGV), which are limited to the measurement of a single flow quantity, FRS can be used for the combined planar measurement of velocity and scalar fields without the need to add a flow tracer. In this study, an FRS concept with the ability to simultaneously measure high-accuracy time-averaged and time-resolved three-component velocity, static pressure and temperature fields is verified on a simplified mock-up of the CCITF facility. Time-averaged results show excellent agreement with benchmark laser Doppler anemometry (LDA) velocities, static pressure probe measurements and analytical temperature calculations. Moreover, it is shown that the developed concept can be used to determine multiple flow variables from a single-frequency measurement, opening the path towards time-resolved multi-parameter measurements by FRS.
Open Access
Seeding-free inlet flow distortion measurements using filtered Rayleigh scattering: integration in a complex intake test facility
(AIAA, 2024-01-04) Migliorini, Matteo; Zachos, Pavlos K.; MacManus, David G.; Doll, Ulrich; Dues, Michael; Jonas, Steinbock J.; Dues, Fritz; Siswanto, Adi; Melnikov, Sergey M.; Rohle, Ingo
Highly integrated propulsion systems to achieve fuel savings and reduction of emissions in future aircrafts call for new measurement methods to assess inlet conditions at the engine fan face. Propulsion systems are expected to operate at higher levels of total pressure, total temperature, and swirl distortion due to flow interaction with aerodynamic surfaces and inherent flow distortion within convoluted intakes. Filtered Rayleigh Scattering (FRS) offers capability to assess all these quantities at once, and without the need of seeding particles which cannot be used for in-flight measurements. This paper aims at increasing the technology readiness level of this measurement technique through the application on a lab-scale S-duct diffuser tests and benchmark against Stereo-Particle Image Velocimetry (S-PIV) measurements. Methods to improve the optical integration and mitigate the effect of varying background conditions are hereby explored. Overall, this represents a step forward in the use of FRS as a turnkey solution for the testing and development phase of future propulsion systems.
Open Access
A study on the development of the flow distortion downstream of an s-duct intake
(ICAS, 2022-09-09) Migliorini, Matteo; Zachos, Pavlos K.; MacManus, David G.; Monnier, Vianney
The use of complex intakes (S-ducts) can enable a closer integration between the airframe and the propulsion system to target a reduction of aircraft fuel consumption, noise, drag, and emissions. However, these advantages may be offset by the increased unsteady flow distortion that arises which can adversely affect the aero-engine. This is also of interest where non-uniform conditions are present at the inlet, for example in Boundary Layer Ingestion (BLI) aircraft. The flow distortion may result in a reduction of the operability range of the engine and in a risk for the development of new propulsion systems. Recently, high-bandwidth Particle Image Velocimetry (PIV) and the statistical modelling of extreme events have been used to assess the S-duct flow distortion. In this work, these methods are used to assess the development of the flow distortion characteristics downstream of the S-duct outlet plane. Non-uniform conditions at the inlet of the S-duct intake produced a sharp growth of the peak distortion levels which is attributed to the increase of local flow unsteadiness that could be linked to the secondary S-duct separation. These peak distortion levels were identified through the modelling of extreme events where the growth of the peak distortion levels was projected beyond the experimental observations. Overall, this work highlights the importance of statistical modelling of the unsteady distortion and shows the development of the unsteady swirl distortion levels downstream of the S-duct outlet plane.
Open Access
Towards time-resolved multi-property measurements by filtered Rayleigh scattering: diagnostic approach and verification
(Springer, 2023-12-11) Doll, Ulrich; Kapulla, Ralf; Dues, Michael; Steinbock, Jonas; Melnikov, Sergey; Röhle, Ingo; Migliorini, Matteo; Zachos, Pavlos K.
The use of multiple perspective views is a possible pathway towards the combined measurement of multiple time-resolved flow properties by filtered Rayleigh scattering (FRS). In this study, a six view observation concept is experimentally verified on a aspirated pipe flow. The concept was introduced in our previous work, and it has the ability to simultaneously measure high-accuracy time-averaged and time-resolved three-component velocity, pressure and temperature fields. To simulate time-resolution, multi-view FRS data at a single optimised excitation frequency are selected and processed for multiple flow properties. Time-averaged and quasi-time-resolved FRS results show very good agreement with differential pressure probe measurements and analytical temperature calculations and lie within ±2 m/s of complementary laser Doppler anemometry (LDA) velocity measurements for all operating points. The introduction of a multistage fitting procedure for the time-resolved analysis leads to a significant improvement of the precision by factors of 4 and 3 for temperature and axial velocity and 18 for pressure. Moreover, both processing methods show their capacity to resolve flow structures in a swirling flow configuration. It is demonstrated that the developed multi-view concept can be used to determine multiple flow variables from a singlefrequency measurement, opening the path towards time-resolved multi-parameter measurements by FRS.
Open Access
Towards time-resolved multi-property measurements by single-frequency FRS
(International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics, 2024-07-08) Doll, Ulrich; Kapulla, Ralf; Dues, Michael; Steinbock, Jonas; Melnikov, Sergey; Röhle, Ingo; Migliorini, Matteo; Zachos, Pavlos K.
The filtered Rayleigh scattering technique (FRS), extended by the method of frequency scanning, has historically been limited to time-averaged multi-property flow measurements. In our recently published work, we present a concept that potentially enables the combined measurement of time-resolved pressure, temperature and three-component (3C) velocity fields. It is based on the observation of the region of interest from six perspectives and a single excitation frequency. This work summarizes and expands on a follow-up publication that experimentally verifies this concept on an aspirated circular duct flow. For this purpose, the results obtained from single-frequency data processing are compared with reference pressures, temperatures and corresponding LDA velocity measurements. Overall, a very good agreement is found for all operating points with accuracies of 3.4% in pressure, 1.3% in temperature and ±2 m/s in axial velocity. Concerning precision, a newly developed multistage evaluation procedure enables values for pressure, temperature and velocity as low as 3 hPa, 2.2 K and 1.7 m/s. In a second flow configuration, an axial swirler is introduced into the duct. The resulting secondary flow structure and deformation of the axial velocity field caused by swirler geometry and support are very well captured with the single-frequency analysis. A closing discussion on the implementation challenges of a single-frequency multi-property FRS instrument with pulsed laser radiation reveals significant obstacles to overcome. Due the considerable optimization potential identified, chances are high that true time-resolved multi-property measurements by FRS will become a reality.

Browsing by Author "Migliorini, Matteo"

Results Per Page

Sort Options