The Impact of Compressor Exit Conditions on Fuel Injector Flows

2012 ◽  
Vol 134 (11) ◽  
Author(s):  
C. L. Ford ◽  
J. F. Carrotte ◽  
A. D. Walker
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Numerical Data ◽  
Flow Fields ◽  
Main Reaction ◽  
Fuel Injector ◽  
Lean Burn ◽  
Field Development ◽  
Inlet Conditions ◽  
The Impact

This paper examines the effect of compressor generated inlet conditions on the air flow uniformity through lean burn fuel injectors. Any resulting nonuniformity in the injector flow field can impact on local fuel air ratios and hence emissions performance. The geometry considered is typical of the lean burn systems currently being proposed for future, low emission aero engines. Initially, Reynolds-averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) predictions were used to examine the flow field development between compressor exit and the inlet to the fuel injector. This enabled the main flow field features in this region to be characterized along with identification of the various stream-tubes captured by the fuel injector passages. The predictions indicate the resulting flow fields entering the injector passages are not uniform. This is particularly evident in the annular passages furthest away from the injector centerline which pass the majority of the flow which subsequently forms the main reaction zone within the flame tube. Detailed experimental measurements were also undertaken on a fully annular facility incorporating an axial compressor and lean burn combustion system. The measurements were obtained at near atmospheric pressure/temperatures and under nonreacting conditions. Time-resolved and time-averaged data were obtained at various locations and included measurements of the flow field issuing from the various fuel injector passages. In this way any nonuniformity in these flow fields could be quantified. In conjunction with the numerical data, the sources of nonuniformities in the injector exit plane were identified. For example, a large scale bulk variation (+/−10%) of the injector flow field was attributed to the development of the flow field upstream of the injector, compared with localized variations (+/−5%) that were generated by the injector swirl vane wakes. Using this data the potential effects on fuel injector emissions performance can be assessed.

The Impact of Compressor Exit Conditions on Fuel Injector Flows

2012 ◽  
Author(s):  
C. L. Ford ◽  
J. F. Carrotte ◽  
A. D. Walker
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Numerical Data ◽  
Flow Fields ◽  
Main Reaction ◽  
Fuel Injector ◽  
Lean Burn ◽  
Field Development ◽  
Inlet Conditions ◽  
The Impact

This paper examines the effect of compressor generated inlet conditions on the air flow uniformity through lean burn fuel injectors. Any resulting non-uniformity in the injector flow field can impact on local fuel air ratios and hence emissions performance. The geometry considered is typical of the lean burn systems currently being proposed for future, low emission aero engines. Initially, RANS CFD predictions were used to examine the flow field development between compressor exit and the inlet to the fuel injector. This enabled the main flow field features in this region to be characterized along with identification of the various stream-tubes captured by the fuel injector passages. The predictions indicate the resulting flow fields entering the injector passages are not uniform. This is particularly evident in the annular passages furthest away from the injector center-line which pass the majority of the flow which subsequently forms the main reaction zone within the flame tube. Detailed experimental measurements were also undertaken on a fully annular facility incorporating an axial compressor and lean burn combustion system. The measurements were obtained at near atmospheric pressure/temperatures and under non-reacting conditions. Time-resolved and time-averaged data were obtained at various locations and included measurements of the flow field issuing from the various fuel injector passages. In this way any non-uniformity in these flow fields could be quantified. In conjunction with the numerical data, the sources of non-uniformities in the injector exit plane were identified. For example, a large scale bulk variation (+/−10%) of the injector flow field was attributed to the development of the flow field upstream of the injector, compared with localized variations (+/−5%) that were generated by the injector swirl vane wakes. Using this data the potential effects on fuel injector emissions performance can be assessed.

scholarly journals IMPACT OF TURBINE-STRUT CLOCKING ON THE PERFORMANCE OF A TURBINE CENTER FRAME

2021 ◽  
pp. 1-17
Author(s):  
Patrick Zeno Sterzinger ◽  
Filippo Merli ◽  
Andreas Peters ◽  
Stephan Behre ◽  
Franz Heitmeir ◽  
...  
Keyword(s):  
Flow Field ◽  
Numerical Data ◽  
Performance Impact ◽  
Test Vehicle ◽  
Low Pressure Turbine ◽  
Second Stage ◽  
University Of Technology ◽  
Turbine Vane ◽  
Carry Over ◽  
The Impact

Abstract Previous studies have indicated a potential for improving the performance of a Turbine Center Frame (TCF) duct by op- timizing the clocking position between the high-pressure-turbine (HPT) vanes and TCF struts. To assess the impact of clocking on the performance, a new test vehicle with a clockable ratio of HPT vanes to TCF struts, consisting of an HPT stage (aero- dynamically representative of the second-stage HPT engine), a TCF duct with non-turning struts, and a first-stage low-pressure turbine vane, was designed and tested in the transonic test tur- bine facility (TTTF) at Graz University of Technology. This paper quantifies the performance impact of clocking and describes the mechanisms causing TCF flow field changes, lever- aging both experimental and numerical data. Other areas in the TCF duct impacted by the choice of the HPT vane circumfer- ential position including the strength of unsteady HPT-TCF in- teraction modes, TCF strut incidence changes, and carry-over effects to the first LPT vane are additionally highlighted. Five-hole-probe (5HP) area traverses and kielhead-rake tra- verses were used to asses the flow field at the TCF-exit and calcu- late the pressure loss. The flow field at the TCF exit shows signif- icant differences depending on the circumferential position of the HPT vane. A relative performance benefit of 5% was achieved.

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.

Impact of Mechanical Chevrons on Supersonic Jet Flow and Noise

2009 ◽  
Author(s):  
K. Kailasanath ◽  
Junhui Liu ◽  
Ephraim Gutmark ◽  
David Munday ◽  
Steven Martens
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Near Field ◽  
Supersonic Jet ◽  
Initial Step ◽  
Nozzle Geometry ◽  
Jet Flows ◽  
Flow Conditions ◽  
Nozzle Geometries ◽  
The Impact

In this paper, we present observations on the impact of mechanical chevrons on modifying the flow field and noise emanated by supersonic jet flows. These observations are derived from both a monotonically integrated large-eddy simulation (MILES) approach to simulate the near fields of supersonic jet flows and laboratory experiments. The nozzle geometries used in this research are representative of practical engine nozzles. A finite-element flow solver using unstructured grids allows us to model the nozzle geometry accurately and the MILES approach directly computes the large-scale turbulent flow structures. The emphasis of the work is on “off-design” or non-ideally expanded flow conditions. LES for several total pressure ratios under non-ideally expanded flow conditions were simulated and compared to experimental data. The agreement between the predictions and the measurements on the flow field and near-field acoustics is good. After this initial step on validating the computational methodology, the impact of mechanical chevrons on modifying the flow field and hence the near-field acoustics is being investigated. This paper presents the results to date and further details will be presented at the meeting.

Characterization of Lean Burn Module Air Blast Pilot Injector With Laser Techniques

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
U. Meier ◽  
S. Freitag ◽  
J. Heinze ◽  
L. Lange ◽  
E. Magens ◽  
...  
Keyword(s):  
Flow Field ◽  
Soot Formation ◽  
Test Methods ◽  
Oh Radicals ◽  
Main Stage ◽  
Fuel Injector ◽  
Lean Burn ◽  
Fuel Ratio ◽  
Optical Test ◽  
Planar Laser

For lean burn combustor development in low emission aero-engines, the pilot stage of the fuel injector plays a key role with respect to stability, operability, NOx emissions, and smoke production. Therefore it is of considerable interest to characterize the pilot module in terms of pilot zone mixing, fuel placement, flow field, and interaction with the main stage. This contribution focuses on the investigation of soot formation during pilot-only operation. Optical test methods were applied in an optically accessible single sector rig at engine idle conditions. Using planar laser-induced incandescence (LII), the distribution of soot and its dependence on air/fuel ratio, as well as geometric injector parameters, was studied. The data shows that below a certain air/fuel ratio, an increase of soot production occurs. This is in agreement with smoke number measurements in a standard single sector flame tube rig without optical access. Reaction zones were identified using chemiluminescence of OH radicals. In addition, the injector flow field was investigated with PIV. A hypothesis regarding the mechanism of pilot smoke formation was made based on these findings. This along with further investigations will form the basis for developing strategies for smoke improvement at elevated pilot-only conditions.

scholarly journals Endwall Heat Transfer Measurements in a Transonic Turbine Cascade

1998 ◽  
Vol 120 (2) ◽  
pp. 305-313 ◽  
Author(s):  
P. W. Giel ◽  
D. R. Thurman ◽  
G. J. Van Fossen ◽  
S. A. Hippensteele ◽  
R. J. Boyle
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Turbine Blade ◽  
Large Scale ◽  
Model Verification ◽  
Quality Data ◽  
Free Stream Turbulence ◽  
Transonic Turbine ◽  
Mach Numbers ◽  
Inlet Conditions

Turbine blade endwall heat transfer measurements are presented for a range of Reynolds and Mach numbers. Data were obtained for Reynolds numbers based on inlet conditions of 0.5 and 1.0 × 106, for isentropic exit Mach numbers of 1.0 and 1.3, and for free-stream turbulence intensities of 0.25 and 7.0 percent. Tests were conducted in a linear cascade at the NASA Lewis Transonic Turbine Blade Cascade Facility. The test article was a turbine rotor with 136 deg of turning and an axial chord of 12.7 cm. The large scale allowed for very detailed measurements of both flow field and surface phenomena. The intent of the work is to provide benchmark quality data for CFD code and model verification. The flow field in the cascade is highly three dimensional as a result of thick boundary layers at the test section inlet. Endwall heat transfer data were obtained using a steady-state liquid crystal technique.

Assessment of RANS Against LES for the Aero-Thermal Behavior of High Pressure Turbine Stages Under Realistic Inlet Conditions

2016 ◽  
Author(s):  
Stefano Vagnoli ◽  
Tom Verstraete ◽  
Charlie Koupper ◽  
Guillaume Bonneau
Keyword(s):  
High Pressure ◽  
Thermal Behavior ◽  
Turbulence Modeling ◽  
Engine Performance ◽  
High Pressure Turbine ◽  
Lean Burn ◽  
Field Development ◽  
Safety Margins ◽  
Inlet Conditions ◽  
Hot Streak

Modern Lean Burn combustors generate a complex field at the High Pressure turbine (HPT) inlet, characterized by non-uniform velocity and temperature distributions, together with very high turbulence levels (up to 25%). For these extreme conditions, classical numerical methods employed for the HPT design, such as Reynolds Averaged Navier Stokes (RANS) simulation, suffer from a lack of validation. This leads to a reduced confidence in predicting the combustor-turbine interactions, which requires to use extra safety margins, to the detriment of the overall engine performance. Within the European FACTOR project, a 360° non reactive combustor simulator and a 1.5 HPT stage are designed to get more insight into the mutual interaction of these two components. A first experimental and numerical campaign has demonstrated the potential of Large Eddy Simulations (LES) to accurately reproduce the turbulent flow field development at the combustor outlet. The aim of the present paper is to exploit the accuracy of LES to validate less time-consuming RANS models in predicting the hot streak migration in the turbine stage. In this sense, LES results are used as a reference to discriminate the different RANS simulations in terms of turbulence modeling and aerothermal predictions. The current investigations clearly indicate that turbulence and hot streak diffusion within the HPT are strongly linked. In this sense, the choice of the RANS turbulence model and the inlet turbulent conditions plays a major role in modeling the thermal behavior for the stator and rotor blades.

Large Eddy Simulations of the Combustor Turbine Interface: Study of the Potential and Clocking Effects

2016 ◽  
Author(s):  
Charlie Koupper ◽  
Guillaume Bonneau ◽  
Laurent Gicquel ◽  
Florent Duchaine
Keyword(s):  
Flow Field ◽  
Leading Edge ◽  
Integrated Approach ◽  
Potential Effect ◽  
Interface Plane ◽  
Mean Flow ◽  
Lean Burn ◽  
Large Eddy ◽  
Inlet Conditions ◽  
Hot Streak

With the generalization of Lean Burn combustors, the flow field entering the turbine tends to feature higher levels of swirl, turbulence, while different hot streak patterns often emerge if compared to the previous generation of combustion chambers. In this context, the combustor-turbine interactions and more specifically the transport of hot streaks through the turbine need to be further analysed to gain engine performance and improved turbine life. Considering this new context, a non-reactive axial combustor simulator representative of a Lean Burn architecture, together with a 1.5 high pressure turbine stage is developed within the European project FACTOR. The interaction between these two modules is numerically investigated by performing Large Eddy Simulation (LES) of the combustor simulator equipped with two Nozzle Guide Vanes (NGVs). By using such an integrated approach, the combustor-turbine interface (plane 40) disappears, allowing: (i) more realistic inlet conditions to the turbine by suppressing all the assumptions associated with averaged profiles; (ii) to account for the potential effect of the vanes on the chamber. Note that if compared to classical approaches, the use of time-resolved LES has the advantage of well predicting the combustor mean flow and turbulence, resulting in more realistic flow properties at the turbine inlet as confirmed by previous works on this configuration. This paper focuses first on two LESs of the combustor-turbine specific configurations: i.e., two clocking positions of the hot streak relative to the NGVs. Significant changes on the thermal field around the vanes are highlighted. When the hot streak is injected in front of a vane leading edge, it considerably heats up the pressure side compared to the adjacent vane although the temperature field is quite uniform at the NGV exit because of the enhanced mixing of the hot streak. On the other hand, when the hot streak is injected in the passage between two adjacent vanes, it remains away from the vane walls preventing them from heating up. The hot streak however crosses the vane passage without being significantly distorted resulting in a more heterogeneous flow field at the rotor inlet. Second, the potential effect induced by the presence of the vanes is investigated by comparing the flow field inside the chamber with and without NGVs. It is found that the potential effect does not alter temperature patterns while a significant radial and azimuthal mass flow redistribution is observed up to about 25% axial chord length upstream of the vanes. The turbulence level is affected by the presence of vanes up to plane 40 when the hot streak is aligned with the passage.

Application of PIV Measurements and Snapshot POD Analysis in a Cylinder Head of Diesel Engine

2017 ◽  
Author(s):  
Zhenyang Zhang ◽  
Hongwei Ma ◽  
Chao Jin ◽  
Cheng Xue ◽  
Yunlong Huang
Keyword(s):  
Diesel Engine ◽  
Flow Field ◽  
Total Energy ◽  
Cylinder Head ◽  
Flow Fields ◽  
Coolant Flow ◽  
Flow Structures ◽  
Fuel Injector ◽  
Piv Measurements ◽  
Water Jacket

The characteristic of coolant flow field in the water jacket of a cylinder head plays an important role in heat exchange, which could even influence the diesel engine’s performance and service life. Measurements and analysis methods to coolant flow field are limited by the complex internal geometrical structure of the cylinder head. In this paper, flow fields in a small and complicated spatial structure are measured by particle image velocimetry (PIV) system and the data are analyzed using proper orthogonal decomposition (POD) method. Time varying coolant flow structures located among two valve seats, a fuel injector seat and a side wall in a real cylinder head are measured by a two dimensional PIV system. PIV results of three measuring planes are displayed in different ways to show flow structures in the water jacket. Distinctive areas can be recognized easily in distributions of different flow parameters. A snapshot POD method is employed to analyze PIV data. Flow structures, which contain different amount of energy, are decomposed into different modes by POD method. POD Mode 1 and ensemble mean flow field are compared together and the relevance index shows a relatively high similarity between these two flow fields. The results also indicate a significant convergence of energy distribution. Energy contained in Mode 1 varies from 22% to 61% of the total energy in different measuring planes. 90% of the total energy is captured in top 10% of the total modes which belong to low-order modes. Energy in high-order modes, which occupy more than 60% of the total modes, contains less than 1% of the total energy. In summary, this paper presents the application of PIV measurements to coolant flow field in a real cylinder head and data processing using a snapshot POD method to analyze PIV results. A set of comprehensive properties showing the spatial and temporal characteristics of coolant flow structure is discussed and concluded detailedly. The data obtained can be used to build an experimental database to optimize coolant flow field structures and verify CFD numerical simulations in order to promote coolant flow passage design and simulation credibility of the diesel engine cooling system.

Numerical Modeling of Centrifugal Compressors With Heterogeneous Incoming Flow due to Low Pressure Exhaust Gas Recirculation

2020 ◽  
Author(s):  
José Galindo ◽  
José Ramón Serrano ◽  
Roberto Navarro ◽  
Guillermo García-Olivas
Keyword(s):  
Flow Field ◽  
Internal Combustion Engines ◽  
Low Pressure ◽  
Mean Flow ◽  
Global Variables ◽  
Compressor Inlet ◽  
Inlet Conditions ◽  
Compressor Map ◽  
The Impact ◽  
Operating Points

Abstract Low pressure EGR (LP-EGR) has become recently one of the most investigated technique in the field of internal combustion engines. When LP-EGR is active, two streams with different psychrometric conditions are mixed at the compressor inlet, i.e. fresh air (considered as cold and dry) and EGR (humid and warm). The main objective of the present work is to assess the impact of the inlet flow heterogeneity, associated with LP-EGR systems, in the performance of centrifugal compressor using 3D CFD simulations. Two intake configurations will be studied, namely a standard straight duct providing the compressor with a homogeneous flow and T junction with a mixing of air and EGR streams. 9 operating points using an EGR rate of 15% (or equivalent inlet conditions for the single duct) are explored. The temporal treatment is firstly assessed, comparing steady RANS simulations against unsteady ones for both intakes, discussing their behavior in terms of global variables and in mean flow field too. These studies show how the steady approach is not enough accurate for predicting the heterogeneity of the flow field in LP-EGR applications. After that, the comparison in global variables between the T-junction inlet and the standard inlet shows slightly differences in terms of compression ratio (around 0.5%) and isentropic efficiency (around 1%). However, in terms of local differences, the case with the standard inlet is clearly not able to predict the temperature heterogeneity of the case with a T-joint. Despite these issues, for an EGR rate of 15%, the global parameters of the compressor are not affected by the T-junction when equivalent operating points are considered in a single duct intake, so this approach can be employed to still use the standard compressor map for LP-EGR applications.

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