Entwicklung eines Smoothed Particle Hydrodynamics (SPH) Codes zur numerischen Vorhersage des Primärzerfalls an Brennstoffeinspritzdüsen

Aufgrund der strengen Schadstoffemissionsrestriktionen zukünftiger Triebwerke bedarf es der Entwicklung effizienter Triebwerkskonzepte. Eine Optimierung des Zerstäubersystems ist unerlässlich. Daher ist es wünschenswert, den Primärzerfall bei der Kraftstoffaufbereitung numerisch vorhersagen zu können. In diesem Forschungsbericht wird systematisch untersucht, ob und inwiefern die gitterfreie Lagrange\u27sche Smoothed Particle Hydrodynamics Methode in diesem Kontext anwendbar ist

Entwicklung eines Smoothed Particle Hydrodynamics (SPH) Codes zur numerischen Vorhersage des Primärzerfalls an Brennstoffeinspritzdüsen [Überarbeitete Version]

Aufgrund der strengen Schadstoffemissionsrestriktionen zukünftiger Triebwerke bedarf es der Entwicklung effizienter Triebwerkskonzepte. Eine Optimierung des Zerstäubersystems ist unerlässlich. Daher ist es wünschenswert, den Primärzerfall bei der Kraftstoffaufbereitung numerisch vorhersagen zu können. In diesem Forschungsbericht wird systematisch untersucht, ob und inwiefern die gitterfreie Lagrange\u27sche Smoothed Particle Hydrodynamics Methode in diesem Kontext anwendbar ist

Modeling of the Deformation Dynamics of Single and Twin Fluid Droplets Exposed to Aerodynamic Loads

Droplet deformation and breakup plays a significant role in liquid fuel atomization processes. The droplet behavior needs to be understood in detail, in order to derive simplified models for predicting the different processes in combustion chambers. Therefore, the behavior of single droplets at low aerodynamic loads was investigated using the Lagrangian, mesh-free Smoothed Particle Hydrodynamics (SPH) method. The simulations to be presented in this paper are focused on the deformation dynamics of pure liquid droplets and fuel droplets with water added to the inside of the droplet. The simulations have been run at two different relative velocities. As SPH is relatively new to Computational Fluid Dynamics (CFD), the pure liquid droplet simulations are used to verify the SPH code by empirical correlations available in literature. Furthermore, an enhanced characteristic deformation time is proposed, leading to a good description of the temporal initial deformation behavior for all investigated test cases. In the further course, the deformation behavior of two fluid droplets are compared to the corresponding single fluid droplet simulations. The results show an influence of the added water on the deformation history. However, it is found that, the droplet behavior can be characterized by the pure fuel Weber number

Numerical Modeling of Oil-Jet Lubrication for Spur Gears using Smoothed Particle Hydrodynamics

Understanding and optimizing the lubrication and cooling in aero engine gearbox applications is crucial for a reliable and efficient sub-system design of future aircraft engines. Due to the complex design of gearboxes with its various rotating parts, space and access for experimental investigations are severely limited. Thus, suitable numerical methods need to be developed in order to thoroughly investigate the evolving oil-air two-phase flow in the vicinity of the gear teeth. In this paper, the impingement of a single oil-jet on a single rotating spur gear was analyzed using the Smoothed Particle Hydrodynamics (SPH) method. The study was conducted with a simplified 2D setup under typical operating conditions met in reduction gear units of novel large civil aircraft engines. Results of the predicted oil-air two-phase flow are presented and compared to conventional Volume-of-Fluid (VOF) simulations. The wetting behavior and the impingement depth of the oil-jet between the gear teeth are investigated for varying oil-jet velocities and rotational speeds. In order to capture three-dimensional flow effects, a 3D setup and preliminary results are presented

Intraductal papillary neoplasms of the bile duct: stepwise progression to carcinoma involves common molecular pathways

Intraductal papillary neoplasms of the bile duct are still poorly characterized regarding (1) their molecular alterations during the development to invasive carcinomas, (2) their subtype stratification and (3) their biological behavior. We performed a multicenter study that analyzed these issues in a large European cohort. Intraductal papillary neoplasms of the bile duct from 45 patients were graded and subtyped using mucin markers and CDX2. In addition, tumors were analyzed for common oncogenic pathways, and the findings were correlated with subtype and grade. Data were compared with those from 22 extra- and intrahepatic cholangiocarcinomas. Intraductal papillary neoplasms showed a development from preinvasive low- to high-grade intraepithelial neoplasia to invasive carcinoma. Molecular and immunohistochemical analysis revealed mutated KRAS, overexpression of TP53 and loss of p16 in low-grade intraepithelial neoplasia, whereas loss of SMAD4 was found in late phases of tumor development. Alterations of HER2, EGFR, β-catenin and GNAS were rare events. Among the subtypes, pancreato-biliary (36%) and intestinal (29%) were the most common, followed by gastric (18%) and oncocytic (13%) subtypes. Patients with intraductal papillary neoplasm of the bile duct showed a slightly better overall survival than patients with cholangiocarcinoma (hazard ratio (cholangiocarcinoma versus intraductal papillary neoplasm of the bile duct): 1.40; 95% confidence interval: 0.46-4.30; P=0.552). The development of biliary intraductal papillary neoplasms of the bile duct follows an adenoma-carcinoma sequence that correlates with the stepwise activation of common oncogenic pathways. Further large trials are needed to investigate and verify the finding of a better prognosis of intraductal papillary neoplasms compared with conventional cholangiocarcinoma