Modal Analysis of Breakup Mechanisms for a Liquid Jet in Crossflow

2021 ◽  
pp. 1-36
Author(s):  
Sheikh Salauddin ◽  
Wilmer Flores ◽  
Michelle Otero ◽  
Bernhard Stiehl ◽  
Kareem Ahmed
Keyword(s):  
Coherent Structures ◽  
Liquid Fuel ◽  
Hydrodynamic Instability ◽  
Aviation Industry ◽  
Dynamic Mode ◽  
Capillary Breakup ◽  
Breakup Mechanism ◽  
Jet In Crossflow ◽  
Fuel Jet ◽  
Primary Breakup

Abstract Liquid fuel jet in Crossflow (LJIC) is a vital atomization technique significant to the aviation industry. The hydrodynamic instability mechanisms that drive a primary breakup of a transverse jet are investigated using modal and traveling wavelength analysis. This study highlights the primary breakup mechanisms for aviation fuel Jet-A, utilizing a method that could be applied to any liquid fuel. Mathematical decomposition techniques known as POD (Proper Orthogonal Decomposition) and Robust MrDMD (Multi-Resolution Dynamic Mode Decomposition) are used together to identify dominant instability flow dynamics associated with the primary breakup mechanism. Implementation of the Robust MrDMD method deconstructs the nonlinear dynamical systems into multiresolution time-scaled components to capture the intermittent coherent structures. The Robust MrDMD, in conjunction with the POD method, is applied to data points taken across the entire spray breakup regimes: enhanced capillary breakup, bag breakup, multimode breakup, and shear breakup. The dominant frequencies of breakup mechanisms are extracted and identified. These coherent structures are classified with an associated time scale and Strouhal number. Three primary breakup mechanisms, namely ligament shedding, bag breakup, and shear breakup, were identified and associated with the four breakup regimes outlined above. Further investigation portrays these breakup mechanisms to occur in conjunction with each other in each breakup regime, excluding the low Weber number Enhanced Capillary Breakup regime. Spectral analysis of the Robust MrDMD modes' entire temporal window reveals that while multiple breakup mechanisms are convolved, there is a dominant breakup route for each breakup regime. An associated particular traveling wavelength analysis further investigates each breakup mechanism. Lastly, this study explores the effects of an increased momentum flux ratio on each breakup mechanism associated with a breakup regime.

Localized Breakup Instabilities for a Liquid Jet in Crossflow

2021 ◽  
Author(s):  
Sheikh Salauddin ◽  
Wilmer Flores ◽  
Michelle Otero ◽  
Kareem Ahmed
Keyword(s):  
Coherent Structures ◽  
Hydrodynamic Instability ◽  
Aviation Industry ◽  
Small Scale ◽  
Dynamic Mode ◽  
Capillary Breakup ◽  
Jet In Crossflow ◽  
Fuel Jet ◽  
Primary Breakup ◽  
Scale Surface

Abstract Liquid fuel jet in Crossflow (LJIC) is significant to the aviation industry since it is a vital technique for atomization. The hydrodynamic instability mechanisms that drive a transverse jet’s primary breakup were investigated using modal and traveling wavelength analysis. This study highlights the primary breakup mechanisms for aviation fuel Jet-A. However, the techniques discussed are applicable to any liquid. Mathematical decomposition techniques are known as POD (Proper Orthogonal Decomposition), and MrDMD (Multi-Resolution Dynamic Mode Decomposition) are used together to identify dominant instability flow dynamics associated with the primary breakup mechanism. Implementation of the MrDMD method deconstructs the nonlinear dynamical systems into multiresolution time-scaled components that capture the intermittent coherent structures. The MrDMD, in conjunction with the POD method, is applied to data points taken across the entire spray breakup regimes, which are: enhanced capillary breakup, bag breakup, multimode breakup, and shear breakup. The dominant frequencies of both breakup regimes are extracted and identified. These coherent structures are classified with an associated time scale and Strouhal number. Characterization of the traveling column and surface wavelengths are conducted and associated with a known instability model. It is found that the Plateau-Rayleigh instability model predicts columns wavelengths similar to wavelengths found in dominant modes associated with a capillary breakup. Rayleigh Taylor’s instability model matches well with bag and multimode breakup. Small scale surface wavelengths associated with a shear breakup are correlated to a modified Rayleigh Taylor instability model founded by Wang et al. [1]. Furthermore, an atomization model that predicts the Sauter Mean Diameter associated with the dominant small-scale surface traveling wavelengths is established.

Modal Analysis on Hydrodynamic Coherent Structures of Liquid Fuel jet in Crossflow

2021 ◽  
Author(s):  
Sheikh Salauddin ◽  
Wilmer Flores ◽  
Michelle Otero ◽  
Kareem A. Ahmed
Keyword(s):  
Modal Analysis ◽  
Coherent Structures ◽  
Liquid Fuel ◽  
Jet In Crossflow ◽  
Fuel Jet

Combustion Characteristics of a Peripheral Vortex Reverse Flow Combustor With Coaxial Fuel Injection

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Raghav Sood ◽  
Preetam Sharma ◽  
Vaibhav Kumar Arghode
Keyword(s):  
Liquid Fuel ◽  
Fuel Injection ◽  
Reverse Flow ◽  
Flame Structure ◽  
Operating Conditions ◽  
Single Digit ◽  
Air Jet ◽  
Fuel Jet ◽  
Primary Breakup ◽  
Reaction Zones

Abstract This paper deals with an experimental investigation of a novel and simple reverse flow combustor, operated stably with a liquid fuel (ethanol) for heat release intensities ranging from 16 to 25 MW/(m3·atm) with very low NOx and CO emissions. The liquid fuel is injected coaxially with the air jet along the centerline of the combustor. The high velocity air annulus helps in primary breakup of the liquid fuel jet. Air injection along the combustor centerline results in a strong peripheral vortex inside the combustor leading to enhanced product gas recirculation, internal preheating of the reactants, and stabilization of reaction zones. Single-digit NOx emissions were obtained for both coaxial fuel injection (non-premixed) and a premixed–prevaporized (PP) cases for all operating conditions. CO emissions for both the modes were less than 100 ppm (ϕ < 0.75). CH* chemiluminescence images revealed two distinct flame structures for coaxial fuel injection case. A single flame structure for PP case was observed extending from the injector exit to the bottom of the combustor. The instantaneous (spatially averaged) CH* intensity fluctuations were significantly lower for the PP case as compared to the coaxial fuel injection case.

Modelling of the atomization of a plain liquid fuel jet in crossflow at gas turbine conditions

2002 ◽  
Vol 6 (7) ◽  
pp. 495-506 ◽  
Author(s):  
Michael Rachner ◽  
Julian Becker ◽  
Christoph Hassa ◽  
Thomas Doerr
Keyword(s):  
Gas Turbine ◽  
Liquid Fuel ◽  
Jet In Crossflow ◽  
Fuel Jet

Novel Modal Analysis Technique for Detecting Localized Breakup of Liquid Fuel Jet in Crossflow

2021 ◽  
Author(s):  
Sheikh Salauddin ◽  
Wilmer Flores ◽  
Michelle Otero ◽  
Kareem A. Ahmed
Keyword(s):  
Modal Analysis ◽  
Liquid Fuel ◽  
Jet In Crossflow ◽  
Analysis Technique ◽  
Fuel Jet

Modal Analysis of Liquid Fuel Jet in Crossflow

2020 ◽  
Author(s):  
Sheikh Salauddin ◽  
Wilmer Flores ◽  
Michelle Otero ◽  
Kareem A. Ahmed
Keyword(s):  
Modal Analysis ◽  
Liquid Fuel ◽  
Jet In Crossflow ◽  
Fuel Jet

Towards Primary Breakup Simulation of a Complete Aircraft Nozzle at Realistic Aircraft Conditions

2020 ◽  
Author(s):  
Katharina Warncke ◽  
Amsini Sadiki ◽  
Max Staufer ◽  
Christian Hasse ◽  
Johannes Janicka
Keyword(s):  
Numerical Simulations ◽  
Liquid Fuel ◽  
Fuel Injection ◽  
Operating Conditions ◽  
Nozzle Geometry ◽  
Nozzle Flow ◽  
Spray Characteristics ◽  
Wide Range ◽  
Primary Breakup ◽  
Turbulent Scales

Abstract Predicting details of aircraft engine combustion by means of numerical simulations requires reliable information about spray characteristics from liquid fuel injection. However, details of liquid fuel injection are not well documented. Indeed, standard droplet distributions are usually utilized in Euler-Lagrange simulations of combustion. Typically, airblast injectors are employed to atomize the liquid fuel by feeding a thin liquid film in the shear zone between two swirled air flows. Unfortunately, droplet data for the wide range of operating conditions during a flight is not available. Focusing on numerical simulations, Direct Numerical simulations (DNS) of full nozzle designs are nowadays out of scope. Reducing numerical costs, but still considering the full nozzle flow, the embedded DNS methodology (eDNS) has been introduced within a Volume of Fluid framework (Sauer et al., Atomization and Sprays, vol. 26, pp. 187–215, 2016). Thereby, DNS domain is kept as small as possible by reducing it to the primary breakup zone. It is then embedded in a Large Eddy Simulation (LES) of the turbulent nozzle flow. This way, realistic turbulent scales of the nozzle flow are included, when simulating primary breakup. Previous studies of a generic atomizer configuration proved that turbulence in the gaseous flow has significant impact on liquid disintegration and should be included in primary breakup simulations (Warncke et al., ILASS Europe, Paris, 2019). In this contribution, an industrial airblast atomizer is numerically investigated for the first time using the eDNS approach. The complete nozzle geometry is simulated, considering all relevant features of the flow. Three steps are necessary: 1. LES of the gaseous nozzle flow until a statistically stationary flow is reached. 2. Position and refinement of the DNS domain. Due to the annular nozzle design the DNS domain is chosen as a ring. It comprises the atomizing edge, where the liquid is brought between inner and outer air flow, and the downstream primary breakup zone. 3. Start of liquid fuel injection and primary breakup simulation. Since the simulation of the two-phase DNS and the LES of the surrounding nozzle flow are conducted at the same time, turbulent scales of the gas flow are directly transferred to the DNS domain. The applicability of eDNS to full nozzle designs is demonstrated and details of primary breakup at the nozzle outlet are presented. In particular a discussion of the phenomenological breakup process and spray characteristics is provided.

Sign in / Sign up

Export Citation Format

Share Document