A hybrid approach combining DNS and RANS simulations to quantify uncertainties in turbulence modelling

Abstract Due to the increasing bypass ratios of modern engines, the fan stage is increasingly becoming the dominant source of engine noise. Accordingly, it is becoming more and more important to develop not only efficient but also quiet fan stages. In this paper the noise emission of a fan for an aero-engine with a bypass ratio of 19 is reduced within a multidisciplinary design optimization (MDO) by means of an hybrid noise prediction method while at the same time optimizing the aerodynamic efficiency. The aerodynamic performance of each configuration in the optimization is evaluated by stationary Reynolds-Averaged Navier-Stokes (RANS) simulations. These stationary flow simulations are also used to extract the aerodynamic excitation sources for the analytical fan noise prediction. The resulting large database of the optimization provides new insights into which extent an MDO can contribute to the design of both quiet and efficient fan stages. In addition to that the hybrid approach of numerical flow solutions and analytical description of the noise sources enables to understand the noise reduction mechanisms. In particular, the influence of rotor blade loading on the aerodynamic efficiency and the noise sources as well as the potential of configurations with a comparatively low number of outlet guide vanes (OGV) is explored. The acoustic results of selected configurations are confirmed by unsteady RANS simulations.

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One-Equation Turbulence Modelling for Atmospheric and Engineering Applications

Boundary-Layer Meteorology ◽

10.1023/b:boun.0000045505.45624.3b ◽

2004 ◽

Vol 113 (3) ◽

pp. 321-346

Author(s):

A. Venetsanos ◽

J. Bartzis ◽

S. Andronopoulos

Keyword(s):

Turbulence Modelling ◽

Engineering Applications

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Surgical and endovascular hybrid approach in peripheral arterial disease of the lower limbs

VASA ◽

10.1024/0301-1526/a000561 ◽

2016 ◽

Vol 45 (5) ◽

pp. 417-422 ◽

Cited By ~ 7

Author(s):

Anouk Grandjean ◽

Katia Iglesias ◽

Céline Dubuis ◽

Sébastien Déglise ◽

Jean-Marc Corpataux ◽

...

Keyword(s):

Mortality Rate ◽

Peripheral Arterial Disease ◽

Limb Salvage ◽

Hybrid Approach ◽

Arterial Disease ◽

Early Mortality ◽

Secondary Patency ◽

Limb Salvage Rate ◽

Peripheral Arterial ◽

Salvage Rate

Abstract. Background: Multilevel peripheral arterial disease is frequently observed in patients with intermittent claudication or critical limb ischemia. This report evaluates the efficacy of one-stage hybrid revascularization in patients with multilevel arterial peripheral disease. Patients and methods: A retrospective analysis of a prospective database included all consecutive patients treated by a hybrid approach for a multilevel arterial peripheral disease. The primary outcome was the patency rate at 6 months and 1 year. Secondary outcomes were early and midterm complication rate, limb salvage and mortality rate. Statistical analysis, including a Kaplan-Meier estimate and univariate and multivariate Cox regression analyses were carried out with the primary, primary assisted and secondary patency, comparing the impact of various risk factors in pre- and post-operative treatments. Results: 64 patients were included in the study, with a mean follow-up time of 428 days (range: 4 − 1140). The technical success rate was 100 %. The primary, primary assisted and secondary patency rates at 1 year were 39 %, 66 % and 81 %, respectively. The limb-salvage rate was 94 %. The early mortality rate was 3.1 %. Early and midterm complication rates were 15.4 % and 6.4 %, respectively. The early mortality rate was 3.1 %. Conclusions: The hybrid approach is a major alternative in the treatment of peripheral arterial disease in multilevel disease and comorbid patients, with low complication and mortality rates and a high limb-salvage rate.

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Hybrid Approach for Conventionally Inoperable Patients with Severe Aortic Valve Stenosis and Coronary Artery Disease

The Thoracic and Cardiovascular Surgeon ◽

10.1055/s-0035-1544426 ◽

2015 ◽

Vol 63 (S 01) ◽

Author(s):

S. Schleger ◽

M. Lieber ◽

J. Rieber ◽

W. Eichinger ◽

J. Szolnoky

Keyword(s):

Coronary Artery Disease ◽

Coronary Artery ◽

Aortic Valve ◽

Aortic Valve Stenosis ◽

Hybrid Approach ◽

Artery Disease

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Delayed Closure of Multiple Muscular Ventricular Septal Defects in an Infant after Coarctation Repair and a Hybrid Procedure�A Case Report

The Heart Surgery Forum ◽

10.1532/hsf98.20101081 ◽

2011 ◽

Vol 14 (1) ◽

pp. 67 ◽

Cited By ~ 2

Author(s):

Ireneusz Haponiuk ◽

Maciej Chojnicki ◽

Radosaw Jaworski ◽

Jacek Juciski ◽

Mariusz Steffek ◽

...

Keyword(s):

Septal Defect ◽

Color Doppler ◽

Hybrid Approach ◽

Ventricular Septal Defects ◽

Color Doppler Echocardiography ◽

Septal Defects ◽

Coarctation Repair ◽

Step Procedure ◽

The Right ◽

Delayed Closure

There are several strategies of surgical approach for the repair of multiple muscular ventricular septal defects (mVSDs), but none leads to a fully predictable, satisfactory therapeutic outcome in infants. We followed a concept of treating multiple mVSDs consisting of a hybrid approach based on intraoperative perventricular implantation of occluding devices. In this report, we describe a 2-step procedure consisting of a final hybrid approach for multiple mVSDs in the infant following initial coarctation repair with pulmonary artery banding in the newborn. At 7 months, sternotomy and debanding were performed, the right ventricle was punctured under transesophageal echocardiographic guidance, and the 8-mm device was implanted into the septal defect. Color Doppler echocardiography results showed complete closure of all VSDs by 11 months after surgery, probably via a mechanism of a localized inflammatory response reaction, ventricular septum growth, and implant endothelization.

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