Numerical study of self-soise produced by an airfoil with trailing-edge serrations

The main objective of the present work is to investigate the mechanism of trailing-edge airfoil noise. The vorticity associated with the unsteady turbulent structures is scattered by the trailing edge and acoustic waves are generated. It has been recognized that trailing-edge noise can be reduced by introducing sharp sawtooth serrations at the trailing-edge. The flow past a serrated airfoil, with free-stream Reynolds number 6.0 × 105 and Mach number M = 0.17, is studied. A compressible Large Eddy Simulation is used for computing the near field, and the far-field acoustic propagation is obtained applying the integral formulation of Ffowcs Williams and Hawkings. The results of the serrated configurations, and its baseline geometry, are compared with the experimental data obtained by ISVR in the frame of the European Project FLOCON. It is shown that the structure of the flow field near the trailing edge is strongly affected by the presence of the serrations. The integral scale lengths of the flow structures in the wake near the trailing edge, are much smaller than in the baseline case. The OASPL directivities of the acoustic far-field are in good agreement with the experimental data, and the serrated airfoil presents a reduction of acoustic PSD in the low and mid frequency ranges, with a reduction ranging from 10 dB at low frequencies, to 5 dB in the mid range. For higher frequencies, the PSD levels of the serrated airfoil become comparable (f = 4000 Hz) and then are higher with respect to the baseline spectru

Numerical prediction method for the acoustic characterization of network elements in presence of mean flow

In the present paper a numerical prediction method for the acoustic characterization of network elements is developed. The acoustic field inside the tested elements is evaluated solving the linearized Euler equations (LEE), or the acoustic perturbation equations (APE), with a discontinuous Galerkin method (DGM). The pressure field is post-processed with a plane wave decomposition method to obtained left- and right-running plane waves at each element port. To characterize the element either the scattering matrix or the impedance is evaluated. For the solution of the hydrodynamic mean flow field the open source Open-FOAM toolbox is used. The numerical method is applied to evaluate the scattering matrix of a sudden area discontinuity both with medium at rest and in presence of mean flow and to evaluate the impedance of an orifice plate as function of the frequency. For both cases the results obtained by the numerical simulations are compared with experimental dat

A predictive model for early mortality after surgical treatment of heart valve or prosthesis infective endocarditis. The EndoSCORE

BACKGROUND: The aim of this large retrospective study was to provide a logistic risk model along an additive score to predict early mortality after surgical treatment of patients with heart valve or prosthesis infective endocarditis (IE). METHODS: From 2000 to 2015, 2715 patients with native valve endocarditis (NVE) or prosthesis valve endocarditis (PVE) were operated on in 26 Italian Cardiac Surgery Centers. The relationship between early mortality and covariates was evaluated with logistic mixed effect models. Fixed effects are parameters associated with the entire population or with certain repeatable levels of experimental factors, while random effects are associated with individual experimental units (centers). RESULTS: Early mortality was 11.0% (298/2715); At mixed effect logistic regression the following variables were found associated with early mortality: age class, female gender, LVEF, preoperative shock, COPD, creatinine value above 2mg/dl, presence of abscess, number of treated valve/prosthesis (with respect to one treated valve/prosthesis) and the isolation of Staphylococcus aureus, Fungus spp., Pseudomonas Aeruginosa and other micro-organisms, while Streptococcus spp., Enterococcus spp. and other Staphylococci did not affect early mortality, as well as no micro-organisms isolation. LVEF was found linearly associated with outcomes while non-linear association between mortality and age was tested and the best model was found with a categorization into four classes (AUC=0.851). CONCLUSIONS: The following study provides a logistic risk model to predict early mortality in patients with heart valve or prosthesis infective endocarditis undergoing surgical treatment, called "The EndoSCORE"

Similar outcome of tricuspid valve repair and replacement for isolated tricuspid infective endocarditis

AimsTo compare early and late mortality of acute isolated tricuspid valve infective endocarditis (TVIE) treated with valve repair or replacement.MethodsPatients who were surgically treated for TVIE from 1983 to 2018 were retrieved from the Italian Registry for Surgical Treatment of Valve and Prosthesis Infective Endocarditis. All the patients were followed up by means of phone interview or calling patient referral physicians or cardiologists. Kaplan-Meier method was used to assess late survival and survival free from TVIE recurrence with log-rank test for univariate comparison. The primary end points were early mortality (30-days after surgery) and long-term survival free from TVIE recurrence.ResultsA total of 4084 patients were included in the registry. Among them, 149 patients were included in the study. Overall, 77 (51.7%) underwent TV repair and 72 (48.3%) TV replacement. Early mortality was 9% (13 patients). Expected early mortality according to EndoSCORE was 12%. The TV repair showed lower mortality and major complication rate (7% and 16%), compared with TV replacement (11% and 25%), but statistical significance was not reached. Median follow-up was 19.1-years (14.3-23.8). Late deaths were 30 and IE recurrences were 5. No difference in cardiac survival free from IE was found between the two groups after 20-years (80-±-6% Repair Group vs 59-±-13% Replacement Group, P = 0.3).ConclusionsOverall results indicate that once surgically addressed, TVIE has a low recurrence rate and excellent survival, apparently regardless of the type of surgery used to treat it

Corrigendum to \u201cA predictive model for early mortality after surgical treatment of heart valve or prosthesis infective endocarditis. The EndoSCORE\u201d. [Int. J. Cardiol. 241 (Aug 15 2017) 97\u2013102](S0167527317309877)(10.1016/j.ijcard.2017.03.148)

The authors regret that the first name and last name of the author Sandro Sponga was published incorrectly in the original version and this has now been corrected