Flow Field Characterization at the Outlet of a Lean Burn Single-Sector Combustor by Laser-Optical Methods

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Michael Schroll ◽  
Ulrich Doll ◽  
Guido Stockhausen ◽  
Ulrich Meier ◽  
Chris Willert ◽  
...  
Keyword(s):  
Rayleigh Scattering ◽  
Pressure Ratio ◽  
Measurement Techniques ◽  
Operating Conditions ◽  
Optical Methods ◽  
Future Application ◽  
Lean Burn ◽  
Optical Access ◽  
Fuel Injectors ◽  
Annular Combustor

High overall pressure ratio (OPR) engine cycles for reduced NOx emissions will generate new aggravated requirements and boundary conditions by implementing low emission combustion technologies into advanced engine architectures. Lean burn combustion systems will have a significant impact on the temperature and velocity traverse at the combustor exit. Lean burn fuel injectors dominate the combustor exit conditions. This is due to the fact that they pass a majority of the total combustor flow, and to the lack of mixing jets like in a conventional combustor. With the transition to high-pressure engines, it is essential to fully understand and determine the high energetic interface between combustor and turbine to avoid excessive cooling. Velocity distributions and their fluctuations at the combustor exit for lean burn are of special interest as they can influence the efficiency and capacity of the turbine. A lean burn single-sector combustor was designed and built at DLR, providing optical access to its rectangular exit section. The sector was operated with a fuel-staged lean burn injector. Measurements were performed under idle and cruise operating conditions. Two velocity measurement techniques were used in the demanding environment of highly luminous flames under elevated pressures: particle image velocimetry (PIV) and filtered Rayleigh scattering (FRS). The latter was used for the first time in an aero-engine combustor environment. In addition to a conventional signal detection arrangement, FRS was also applied with an endoscope for signal collection, to assess its practicality for a potential future application in a full annular combustor with restricted optical access.

Temperature Measurements at the Outlet of a Lean Burn Single-Sector Combustor by Laser Optical Methods

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Ulrich Doll ◽  
Guido Stockhausen ◽  
Johannes Heinze ◽  
Ulrich Meier ◽  
Christoph Hassa ◽  
...  
Keyword(s):  
Rayleigh Scattering ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
Optical Methods ◽  
Future Application ◽  
Lean Burn ◽  
Spatially Resolved ◽  
Combined Application ◽  
Planar Laser ◽  
Annular Combustor

High overall pressure ratio (OPR) engine cycles for reduced NOx emissions will generate new aggravated requirements and boundary conditions by implementing low emission combustion technologies into advanced engine architectures. Lean burn combustion systems will have a significant impact on the temperature and velocity traverse at the combustor exit. With the transition to high-pressure engines, it is essential to fully understand and determine the high energetic interface between combustor and turbine to avoid excessive cooling. Spatially resolved temperatures were measured at different operating conditions using planar laser-induced fluorescence of OH (OH-PLIF) and filtered Rayleigh scattering (FRS), the latter being used in a combustor environment for the first time. Apart from a conventional signal detection arrangement, FRS was also applied with an endoscope for signal collection, to assess its feasibility for future application in a full annular combustor with restricted optical access. Both techniques are complementary in several respects, which justified their combined application. OH-PLIF allows instantaneous measurements and therefore enables local temperature statistics, but is limited to relatively high temperatures. On the other hand, FRS can also be applied at low temperatures, which makes it particularly attractive for measurements in cooling layers. However, FRS requires long sampling times and therefore can only provide temporal averages. When applied in combination, the accuracy of both techniques could be improved by each method helping to overcome the other's shortcomings.

Flow Field Characterization at the Outlet of a Lean Burn Single Sector Combustor by Laser-Optical Methods

2016 ◽  
Author(s):  
M. Schroll ◽  
U. Doll ◽  
G. Stockhausen ◽  
U. Meier ◽  
C. Willert ◽  
...  
Keyword(s):  
Rayleigh Scattering ◽  
Measurement Techniques ◽  
Light Sheet ◽  
Operating Conditions ◽  
Optical Methods ◽  
Future Application ◽  
Exit Section ◽  
Lean Burn ◽  
Optical Access ◽  
Eu Project

High OPR engine cycles for reduced NOx emissions will generate new aggravated requirements and boundary conditions by implementing low emission combustion technologies into advanced engine architectures. Lean burn combustion systems will have a significant impact on the temperature and velocity traverse at the combustor exit. Lean burn fuel injectors dominate the combustor exit conditions. This is due to the fact that they pass a majority of the total combustor flow, and to the lack of mixing jets like in a conventional combustor. With the transition to high pressure engines it is essential to fully understand and determine the high energetic interface between combustor and turbine to avoid excessive cooling, which has a detrimental impact on turbine and overall engine efficiency. Velocity distributions and their fluctuations at the combustor exit for lean burn are of special interest as they can influence the efficiency and capacity of the turbine. Within the EU project LEMCOTEC, a lean burn single sector combustor was designed and built at DLR, providing optical access to its rectangular exit section. The sector was operated with a fuel staged lean burn injector from Rolls-Royce Deutschland. Measurements were performed under various operating conditions, covering idle and cruise operation. Two techniques were used to perform velocity measurements at the combustor exit in the demanding environment of highly luminous flames under elevated pressures: Particle Image Velocimetry (PIV) and Filtered Rayleigh Scattering (FRS). The latter was used for the first time in an aero-engine combustor environment. In addition to a conventional signal detection arrangement, FRS was also applied with an endoscope for signal collection, to assess its practicality for a potential future application in a full annular combustor with restricted optical access. Both measurement techniques are complementary in several respects, which justified their respective application and comparative assessment. PIV is able to record instantaneous velocity distributions and is therefore capable to deliver higher velocity moments, in addition to temporal averages. Applied in two orthogonal traversable light sheet arrangements, it could be used to map all three velocity components across the entire combustor cross section, and obtain data on velocity variances, cross-correlations and turbulence intensities. FRS is limited to measurements of average velocities, as long sampling times are required due to the weak physical process of Rayleigh scattering. However, FRS has two advantages: It requires no particle seeding, because it is based on the measurement of a molecular Doppler shift, and it can provide temperature information simultaneously. This contribution complements a second paper (GT2016-56370) focusing on the measurement of temperature distributions at the same combustor exit section by laser-based optical methods.

Temperature Measurements at the Outlet of a Lean Burn Single Sector Combustor by Laser-Optical Methods

2016 ◽  
Author(s):  
U. Doll ◽  
G. Stockhausen ◽  
J. Heinze ◽  
U. Meier ◽  
C. Hassa ◽  
...  
Keyword(s):  
Rayleigh Scattering ◽  
Swirling Flow ◽  
Operating Conditions ◽  
Optical Methods ◽  
Future Application ◽  
Special Importance ◽  
Fuel Injector ◽  
Lean Burn ◽  
Optical Access ◽  
Combined Application

High OPR engine cycles for reduced NOx emissions will generate new aggravated requirements and boundary conditions by implementing low emission combustion technologies into advanced engine architectures. Lean burn combustion systems will have a significant impact on the temperature and velocity traverse at the combustor exit. The highly swirling flow from the lean burn fuel injector interacts with the combustor wall cooling before exiting the combustor. As a large portion (up to 80%) of the total flow passes through the fuel injector, the combustor exit flow and temperature field is dominated by the fuel injector. With the transition to high pressure engines it is essential to fully understand and determine the high energetic interface between combustor and turbine to avoid excessive cooling with detrimental impacts to turbine and overall engine efficiency. In this context the knowledge of temperature distributions at the combustor exit is of special importance. A lean burn single sector combustor was designed and built at DLR, providing optical access to the exit section. The sector was operated with a staged lean burn injector from Rolls-Royce Deutschland. Spatially resolved temperatures were measured at different operating conditions using planar laser-induced fluorescence of OH (OH-PLIF) and Filtered Rayleigh Scattering (FRS), the latter being used in a combustor environment for the first time. Apart from a conventional signal detection arrangement, FRS was also applied with an endoscope for signal collection, to assess its feasibility for future application in a full annular combustor with restricted optical access. Both techniques are complementary in several respects, which justified their combined application and comparative assessment in this specific environment. OH-PLIF allows instantaneous measurements and therefore enables local temperature statistics, but is limited to relatively high temperatures. On the other hand FRS can also be applied at low temperatures, which makes it particularly attractive for measurements in cooling layers. However, due to the weak physical process of Rayleigh scattering, FRS requires long sampling times and therefore can only provide temporal averages. When applied in combination, the accuracy of both techniques could be improved by each method helping to overcome the other’s shortcomings. In an accompanying paper, additional experiments are described which characterize the flow field at the combustor exit; the combined data provide comprehensive information on combustor exit conditions.

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.

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

2014 ◽  
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, 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.

Turning Mid Turbine Frame Behavior for Different HP Turbine Outflow Conditions

2011 ◽  
Author(s):  
Berardo Paradiso ◽  
Cornelia Santner ◽  
Josef Hubinka ◽  
Emil Go¨ttlich ◽  
Martin Hoeger
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
Pressure Ratio ◽  
Measurement Techniques ◽  
Operating Conditions ◽  
Time Resolved ◽  
Flow Angle ◽  
The Mean ◽  
Eu Project ◽  
The Eu

The design of turbine frames with turning vanes, known as turning mid-turbine frames (TMTF), becomes of great importance for high by-pass ratio engines with counter-rotating turbines. To achieve a more efficient low-pressure turbine the overall diffusion and radial offset should be increased. One goal of the EU project DREAM is to analyse the flow through a TMTF and a downstream arranged counter rotating LP rotor. The investigation of these complex interrelationships has been performed in the unique two-spool continuously operating transonic test turbine facility at Graz University of Technology. The test setup consists of an unshrouded HP stage, the TMTF and a shrouded LP rotor. The shafts of both turbines are mechanically independent, so the test rig allows a realistic two shaft turbine operation. The TMTF flow field is highly complex. It is a turbulent and unsteady flow dominated by strong secondary flows and vortex-interactions. The upstream transonic high pressure turbine stage produces a complex inflow with high levels of turbulence, stationary and rotating wakes and vortical structures. Therefore the application of advanced measurement techniques is necessary. To describe the HP-TMTF interaction time-resolved pressure measurements have applied within the project. The TMTF was instrumented with 10 fast response pressure transducers; static pressure tap recordings on the strut and on the TMTF end-walls have been also applied. Five hole probe, total pressure and total temperature rakes have been additionally acquired in the planes just in front of the struts and downstream to evaluate the performance of the TMTF. The results of these conventional techniques are presented in this work and they represent the necessary starting point for the evaluation and the description of the flow field. The idea is to start the study analysing the mean quantities and the overall performance of the two stages for different conditions and to leave the analysis of the time-resolved results for further investigation. Detailed investigations will start from the data presented in this paper; indeed, the use of unsteady measurement techniques is time consuming and cannot be performed for such a large amount of flow conditions, radial planes and HP vane - TMTF relative positions. Three operating conditions for different clocking positions have been considered. The variation of the operating conditions has been achieved by varying the HP shaft velocity and pressure ratio, with a consequence change of pressure ratio in the LP rotor. For this analysis the LP shaft velocity was kept constant. The TMTF performance variations will be analysed in terms of total pressure loss coefficient and exit flow angle; the mean interaction between the structures coming from the HP stage and the struts will represent the interpretation key to explain these variations. This work is part of the EU project DREAM (ValiDation of Radical Engine Architecture SysteMs, contract No. ACP7-GA-2008-211861).

Tire Experimental Characterization Using Contactless Measurement Methods

2021 ◽  
Keyword(s):  
Combustion Engine ◽  
Measurement Techniques ◽  
Laser Doppler Vibrometer ◽  
Operating Conditions ◽  
Image Correlation ◽  
Optical Methods ◽  
Mode Shapes ◽  
Contactless Measurement ◽  
Full Field ◽  
Static Conditions

In the frame of automotive Noise Vibration and Harshness (NVH) evaluation, inner cabin noise is among the most important indicators. The main noise contributors can be identified in engine, suspensions, tires, powertrain, brake system, etc. With the advent of E-vehicles and the consequent absence of the Internal Combustion Engine (ICE), tire/road noise has gained more importance, particularly at mid-speed driving and in the spectrum up to 300 Hz. At the state of the art, the identification and characterization of Noise and Vibration sources rely on pointwise sensors (microphones, accelerometers, strain gauges). Optical methods such as Digital Image Correlation (DIC) and Laser Doppler Vibrometer (LDV) have recently received special attention in the NVH field because they can be used to obtain full-field measurements. Moreover, these same techniques could also allow to characterize the tire behavior in operating conditions, which would be practically impossible to derive with standard techniques. In this paper we will demonstrate how non-contact full-field measurement techniques can be used to reliably and robustly characterize the tire behavior up to 300 Hz, focusing on static conditions. Experimental modal analysis will extract the modal characteristic of the tire in both free-free and statically preloaded boundary conditions, using both DIC and LDV. The extracted natural frequencies, damping ratios and full-field mode shapes will be used on one side to improve the accuracy of tire models (either by deriving FRF based models or updating FE ones) but also as a reference for future investigation on the tire behavior characterization in rotating conditions.

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.

scholarly journals Large Eddy Simulations of Strongly Non-Ideal Compressible Flows through a Transonic Cascade

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 772
Author(s):  
Jean-Christophe Hoarau ◽  
Paola Cinnella ◽  
Xavier Gloerfelt
Keyword(s):  
Compressible Flows ◽  
Flow Behavior ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Ideal Gas ◽  
Operating Conditions ◽  
Large Eddy Simulations ◽  
Working Fluid ◽  
Viscous Effects ◽  
Large Eddy

Transonic flows of a molecularly complex organic fluid through a stator cascade were investigated by means of large eddy simulations (LESs). The selected configuration was considered as representative of the high-pressure stages of high-temperature Organic Rankine Cycle (ORC) axial turbines, which may exhibit significant non-ideal gas effects. A heavy fluorocarbon, perhydrophenanthrene (PP11), was selected as the working fluid to exacerbate deviations from the ideal flow behavior. The LESs were carried out at various operating conditions (pressure ratio and total conditions at inlet), and their influence on compressibility and viscous effects is discussed. The complex thermodynamic behavior of the fluid generates highly non-ideal shock systems at the blade trailing edge. These are shown to undergo complex interactions with the transitional viscous boundary layers and wakes, with an impact on the loss mechanisms and predicted loss coefficients compared to lower-fidelity models relying on the Reynolds-averaged Navier–Stokes (RANS) equations.

Compressible Flowfield Characteristics of Butterfly Valves

1989 ◽  
Vol 111 (4) ◽  
pp. 400-407 ◽  
Author(s):  
M. J. Morris ◽  
J. C. Dutton
Keyword(s):  
Flow Separation ◽  
Pressure Ratio ◽  
Disk Surface ◽  
Surface Flow ◽  
Operating Conditions ◽  
Local Geometry ◽  
Operating Pressure ◽  
Butterfly Valve ◽  
Pressure Distributions ◽  
Flow Separation And Reattachment

The results of an experimental investigation into the flowfield characteristics of butterfly valves under compressible flow operating conditions are reported. The experimental results include Schlieren and surface flow visualizations and flowfield static pressure distributions. Two valve disk shapes have been studied in a planar, two-dimensional test section: a generic biconvex circular arc profile and the midplane cross-section of a prototype butterfly valve. The valve disk angle and operating pressure ratio have also been varied in these experiments. The results demonstrate that under certain conditions of operation the butterfly valve flowfield can be extremely complex with oblique shock waves, expansion fans, and regions of flow separation and reattachment. In addition, the sensitivity of the valve disk surface pressure distributions to the local geometry near the leading and trailing edges and the relation of the aerodynamic torque to flow separation and reattachment on the disk are shown.

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