Multi-objective Numerical Investigation of a Generic Airblast Injector Design

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Adam L. Comer ◽  
Timoleon Kipouros ◽  
R. Stewart Cant
Keyword(s):  
Design Space ◽  
Direct Injection ◽  
Design Studies ◽  
Lean Direct Injection ◽  
Analytical Work ◽  
Computational Fluid Dynamics Cfd ◽  
Aero Engines ◽  
Semi Empirical ◽  
Injector Design ◽  
Low Order

In combustor design for aero-engines, engineers face multiple opposing objectives with strict constraints. The trend toward lean direct injection (LDI) combustors suggests a growing emphasis on injector design to balance these objectives. Decades of empirical and analytical work have produced low-order methods, including semi-empirical and semi-analytical correlations and models of combustors and their components, but detailed modeling of injector and combustor behavior requires computational fluid dynamics (CFD). In this study, an application of low-order methods and published guidelines yielded generic injector and combustor geometries, as well as CFD boundary conditions of parameterized injector designs. Moreover, semi-empirical correlations combined with a numerical spray combustion solver provided injector design evaluations in terms of pattern factor, thermoacoustic performance, and certain emissions. Automation and parallel coordinate visualization enabled exploration of the dual-swirler airblast injector design space, which is often neglected in published combustor design studies.

Numerical Study of Lean-Direct Injection Combustor With Discrete-Jet Swirlers Using Reynolds Stress Model

2003 ◽  
Vol 125 (4) ◽  
pp. 1059-1065 ◽  
Author(s):  
S. L. Yang ◽  
Y. K. Siow ◽  
C. Y. Teo ◽  
R. R. Tacina ◽  
A. C. Iannetti ◽  
...  
Keyword(s):  
Reynolds Stress ◽  
Turbulence Model ◽  
Numerical Study ◽  
Direct Injection ◽  
Reynolds Stress Model ◽  
Lean Direct Injection ◽  
Velocity Gradients ◽  
Recirculation Zones ◽  
Computational Fluid Dynamics Cfd ◽  
Reynolds Averaging

The flowfield in a lean-direct injection (LDI) combustor with discrete-jet swirlers is described and analyzed using a computational fluid dynamics (CFD) code with a Reynolds stress turbulence model (RSTM). The results from the RSTM are compared to time-averaged laser-Doppler velocimetry (LDV) data, as well as results from the National Combustion Code (NCC) that has a cubic nonlinear κ-ε turbulence model, and from the KIVA code using the standard κ-ε model. The comparisons of results indicate that the RSTM accurately describes the flow details and resolves recirculation zones and high velocity gradients while the κ-ε models are unable to capture most flow structures. This confirms that, within the Reynolds averaging approach, the higher-order RSTM is preferred for simulating complex flowfields where separations, strong anisotropy, and high swirl are present.

Combustion Dynamics Behavior in a Single-Element Lean Direct Injection (LDI) Gas Turbine Combustor

2014 ◽  
Author(s):  
Cheng Huang ◽  
Rohan Gejji ◽  
William Anderson ◽  
Changjin Yoon ◽  
Venkateswaran Sankaran
Keyword(s):  
Gas Turbine ◽  
Direct Injection ◽  
Single Element ◽  
Gas Turbine Combustor ◽  
Combustion Dynamics ◽  
Lean Direct Injection

scholarly journals Vortex breakdown of the swirling flow in a Lean Direct Injection burner

2020 ◽  
Vol 32 (12) ◽  
pp. 125118
Author(s):  
Yazhou Shen ◽  
Mohamad Ghulam ◽  
Kai Zhang ◽  
Ephraim Gutmark ◽  
Christophe Duwig
Keyword(s):  
Vortex Breakdown ◽  
Swirling Flow ◽  
Direct Injection ◽  
Lean Direct Injection ◽  
Injection Burner

Artificially Ventilated Cavities: Evaluating the Constant-Pressure Approximation

2017 ◽  
Author(s):  
Melissa A. Fronzeo ◽  
Michael Kinzel ◽  
Jules Lindau
Keyword(s):  
Constant Pressure ◽  
Flow Behavior ◽  
Internal Cavity ◽  
Common Assumption ◽  
Ventilated Cavity ◽  
Physical Insight ◽  
Circulatory Flow ◽  
Computational Fluid Dynamics Cfd ◽  
The Common ◽  
Semi Empirical

Computational Fluid Dynamics (CFD) is employed to study the fundamental aspects of the internal pressure within artificially ventilated, gaseous cavities in both twin- and toroidal-vortex closure modes. The results show that several pressure regions develop within the cavities, indicating that the common assumption that the cavity has a constant pressure breaks down when evaluated in high detail. The internal cavity pressure is evaluated using a probability density function (PDF). The resulting PDF plots show a clusters with multiple peaks. A mixture-of-Gaussians (MOG) method is employed to better understand the distributions of these peaks. These peaks are then mapped to the simulation results, where it is observed that these peaks correlate to distinct cavity regions (which vary depending on cavity type). Moreover, these varying pressure regions appear to align with cavity-radius growth and reduction and appear to be the driving force of the internal, circulatory flow. Lastly, the importance of these pressure regions are investigated with respect to predictions from semi-empirical theory of the cavity shape, showing a moderate impact depending on where the cavity is probed. Overall, these results provide physical insight into ventilated cavity flow behavior that is often ignored.

Low Order Modeling for Fan and Outlet Guide Vanes in Aero-Engines

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Jiahuan Cui ◽  
Rob Watson ◽  
Yunfei Ma ◽  
Paul Tucker
Keyword(s):  
Detailed Analysis ◽  
Immersed Boundary Method ◽  
Low Cost ◽  
Immersed Boundary ◽  
Test Case ◽  
Guide Vanes ◽  
Compression System ◽  
Aero Engine ◽  
Aero Engines ◽  
Low Order

Intakes of reduced length have been proposed with the aim of producing aero-engines with higher efficiency and reduced weight. As the intake length decreases, it is expected that stronger effects of the fan on the flow over the intake lip will be seen. If the effects of the fan cannot be ignored, a low-cost but still accurate fan model is of great importance for designing a short-intake. In this paper, a low order rotor/stator model, the immersed boundary method with smeared geometry (IBMSG), has been further developed and validated on a rig test case. The improved IBMSG is more robust than the original. The rig test case used for validation features a low-pressure compression system with a nonaxisymmetric inflow, which is representative of the inlet condition of an aero-engine at its cruise condition. Both the fan and the outlet guide vanes (OGVs) are modeled using IBMSG. A detailed analysis is carried out on the flow both upstream and downstream of the fan. After validating the IBMSG method against the rig test case, a short-intake case, coupled with a fan designed for the next generation of aero-engines, is further investigated. It is found that compared with the intake-alone case, the inflow distortion at the fan face is significantly reduced by the presence of fan. Due to this increased interaction between the fan and the flow over the intake lip, accounting for the effects of the downstream fan is shown to be essential when designing a short intake.

scholarly journals Characterization of a Novel Porous Injector for Multi-Lean Direct Injection (M-LDI) Combustor

2017 ◽  
Author(s):  
Jianing Li ◽  
Umesh Bhayaraju ◽  
San-Mou Jeng
Keyword(s):  
Air Temperature ◽  
Mass Fraction ◽  
Direct Injection ◽  
Flame Temperature ◽  
Gaseous Fuel ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Porous Tube ◽  
Lean Direct Injection ◽  
Air Mixing

A generic novel injector was designed for multi-Lean Direct Injection (M-LDI) combustors. One of the drawbacks of the conventional pressure swirl and prefilming type airblast atomizers is the difficulty of obtaining a uniform symmetric spray under all operating conditions. Micro-channels are needed inside the injector for uniformly distributing the fuel. The problem of non-uniformity is magnified in smaller sized injectors. The non-uniform liquid sheet causes local fuel rich/lean zones leading to higher NOx emissions. To overcome these problems, a novel fuel injector was designed to improve the fuel delivery to the injector by using a porous stainless steel material with 30 μm porosity. The porous tube also acts as a prefilming surface. Liquid and gaseous fuels can be injected through the injector. In the present study, gaseous fuel was injected to investigate injector fuel-air mixing performance. The gaseous fuel was injected through a porous tube between two radial-radial swirling air streams to facilitate fuel-air mixing. The advantage of this injector is that it increases the contact surface area between the fuel-air at the fuel injection point. The increased contact area enhances fuel-air mixing. Fuel-air mixing and combustion studies were carried out for both gaseous and liquid fuel. Flame visualization, and emissions measurements were carried out inside the exit of the combustor. The measurements were carried out at atmospheric conditions under fuel lean conditions. Natural gas was used as a fuel in these experiments. Fuel-air mixing studies were carried out at different equivalence ratios with and without confinement. The mass fraction distributions were measured at different downstream locations from the injector exit. Flame characterization was carried out by chemiluminescence at different equivalence ratios and inlet air temperatures. Symmetry of the flame, flame length and heat release distribution were analyzed from the flame images. The effects of inlet air temperature and combustion flame temperature on emissions was studied. Emissions were corrected to 15% O2 concentration. NOx emissions increase with inlet air temperature and flame temperature. Effect of flame temperature on NOx concentration is more significant than effect of inlet air temperature. Fuel-air mixing profile was used to obtain mass fraction Probability Density Function (pdf). The pdfs were used for simulations in Chemkin Pro. The measured emissions concentrations at the exit of the injector was compared with simulations. In Chemkin model, a network model with several PSRs (perfectly stirred reactor) were utilized, followed by a mixer and a PFR (plug flow reactor). The comparison between the simulations and the experimental results was investigated.

VIV Assessment of Deepwater Lazy-Wave Risers

2014 ◽  
Author(s):  
Yiannis Constantinides ◽  
Michelle Zhang
Keyword(s):  
Cfd Simulation ◽  
Dynamic Stresses ◽  
Global Response ◽  
Software Analysis ◽  
Computational Fluid Dynamics Cfd ◽  
Improved Performance ◽  
Viv Suppression ◽  
Different Response ◽  
Semi Empirical ◽  
Harsh Conditions

The steel lazy wave riser is an emerging solution for deepwater applications in harsh conditions. The addition of buoyancy to provide the unique “lazy wave” shape reduces the dynamic stresses at the touchdown zone resulting in improved performance due to vessel motions and waves. However as the buoyant region cannot be easily fitted with Vortex-Induced Vibration (VIV) suppression, VIV becomes a critical aspect of the design. The present study focuses on understanding the global response of a deepwater lazy wave riser with a combination of computational fluid dynamics (CFD) and semi-empirical software analysis. An industry first full scale CFD simulation with different buoyancy region geometries is presented and analyzed to understand the field response and provide guidance on important aspects of design. Results show a different response than what was expected based on previous testing of similar systems, introducing a new parameter related to the aspect ratio of the buoyancy modules.

scholarly journals Enabling the potential of hybrid electric propulsion through lean-burn-combustion turbofans

2021 ◽  
Vol 5 ◽  
pp. 164-176
Author(s):  
Stavros Vouros ◽  
Mavroudis Kavvalos ◽  
Smruti Sahoo ◽  
Konstantinos Kyprianidis
Keyword(s):  
Electric Propulsion ◽  
Direct Injection ◽  
Operating Cost ◽  
Pollutant Emissions ◽  
Civil Aviation ◽  
Lean Burn ◽  
Lean Direct Injection ◽  
Direct Operating Cost ◽  
Hybrid Electric ◽  
The Impact

Hybrid-electric propulsion has emerged as a promising technology to mitigate the adverse environmental impact of civil aviation. Boosting conventional gas turbines with electric power improves mission performance and operability. In this work the impact of electrification on pollutant emissions and direct operating cost of geared turbofan configurations is evaluated for an 150-passenger aircraft. A baseline two-and-a-half-shaft geared turbofan, representative of year 2035 entry-into-service technology, is employed. Parallel hybridization is implemented through coupling a battery-powered electric motor to the engine low-speed shaft. A multi-disciplinary design space exploration framework is employed comprising modelling methods for multi-point engine design, aircraft sizing, performance and pollutant emissions, mission and economic analysis. A probabilistic approach is developed considering uncertainties in the evaluation of direct operating cost. Sensitivities to electrical power system technology levels, as well as fuel price and emissions taxation are quantified at different time-frames. The benefits of lean direct injection are explored along short-, medium-, and long-range missions, demonstrating 32% NO<italic><sub>x</sub></italic> savings compared to traditional rich-burn, quick-mix, lean-burn technologies in short-range operations. The impact of electrification on the enhancement of lean direct injection benefits is investigated. For hybrid-electric powerplants, the take-off-to-cruise turbine entry temperature ratio is 2.5% lower than the baseline, extending the corresponding NO<italic><sub>x</sub></italic> reductions to the level of 46% in short-range missions. This work sheds light on the environmental and economic potential and limitations of a hybrid-electric propulsion concept towards a greener and sustainable civil aviation.

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