Airfoil Tip Leakage Aeroacoustics Predictions using a Lattice Boltzmann Based Method

International audienceThe noise produced by rotating systems such as fans and turbo machines is of growing importance in the academic and engineering communities. The prediction and understanding of the physical mechanisms associated with noise generation are required in order to develop innovative solutions able to efficiently reduce radiated acoustics levels. The flow-induced noise generation mechanisms related to rotating devices are various and complex, and one of them is related to the blade tip flow. The tip flow noise, or tip leakage noise, is particularly important for free-tip configurations, for which the tip flow induced by the pressure gradient between the suction and pressure sides can be particularly intense. The experimental investigation of this mechanism is practically challenging. Consequently, a simplified non-rotating representative configuration has been proposed, and has been previously investigated experimentally. In this paper, transient, compressible, and time-explicit Computational Fluid Dynamics/Computational Aero-Acoustics (CFD/CAA) simulations of an airfoil tip leakage flow for this simplified geometry are performed using a Lattice Boltzmann Method (LBM) based approach. The studied configuration is a NACA 5510 airfoil profile at high Reynolds number flow conditions, for which a variable size gap is introduced between the airfoil and one of the end plates, modeling the tip gap encountered in free-tip fans. First, the simulation results are compared with experimental results to validate the numerical approach. Further investigation of the numerical results underlines the connection between the tip vortex structures and noise radiation, including a parametric study on the Angle of Attack (AoA) and the tip gap width

Airfoil Tip Leakage Aeroacoustics Predictions using a Lattice Boltzmann Based Method

The noise produced by rotating systems such as fans and turbo machines is of growing importance in the academic and engineering communities. The prediction and understanding of the physical mechanisms associated with noise generation are required in order to develop innovative solutions able to efficiently reduce radiated acoustics levels. The flow-induced noise generation mechanisms related to rotating devices are various and complex, and one of them is related to the blade tip flow. The tip flow noise, or tip leakage noise, is particularly important for free-tip configurations, for which the tip flow induced by the pressure gradient between the suction and pressure sides can be particularly intense. The experimental investigation of this mechanism is practically challenging. Consequently, a simplified non-rotating representative configuration has been proposed, and has been previously investigated experimentally. In this paper, transient, compressible, and time-explicit Computational Fluid Dynamics/Computational Aero-Acoustics (CFD/CAA) simulations of an airfoil tip leakage flow for this simplified geometry are performed using a Lattice Boltzmann Method (LBM) based approach. The studied configuration is a NACA 5510 airfoil profile at high Reynolds number flow conditions, for which a variable size gap is introduced between the airfoil and one of the end plates, modeling the tip gap encountered in free-tip fans. First, the simulation results are compared with experimental results to validate the numerical approach. Further investigation of the numerical results underlines the connection between the tip vortex structures and noise radiation, including a parametric study on the Angle of Attack (AoA) and the tip gap width

The Plasminogen Activator Inhibitor PAI-1 Controls in Vivo Tumor Vascularization by Interaction with Proteases, Not Vitronectin: Implications for Antiangiogenic Strategies

The plasminogen (Plg)/plasminogen activator (PA) system plays a key role in cancer progression, presumably via mediating extracellular matrix degradation and tumor cell migration. Consequently, urokinase-type PA (uPA)/plasmin antagonists are currently being developed for suppression of tumor growth and angiogenesis. Paradoxically, however, high levels of PA inhibitor 1 (PAI-1) are predictive of a poor prognosis for survival of patients with cancer. We demonstrated previously that PAI-1 promoted tumor angiogenesis, but by an unresolved mechanism. We anticipated that PAI-1 facilitated endothelial cell migration via its known interaction with vitronectin (VN) and integrins. However, using adenoviral gene transfer of PAI-1 mutants, we observed that PAI-1 promoted tumor angiogenesis, not by interacting with VN, but rather by inhibiting proteolytic activity, suggesting that excessive plasmin proteolysis prevents assembly of tumor vessels. Single deficiency of uPA, tissue-type PA (tPA), uPA receptor, or VN, as well as combined deficiencies of uPA and tPA did not impair tumor angiogenesis, whereas lack of Plg reduced it. Overall, these data indicate that plasmin proteolysis, even though essential, must be tightly controlled during tumor angiogenesis, probably to allow vessel stabilization and maturation. These data provide insights into the clinical paradox whereby PAI-1 promotes tumor progression and warrant against the uncontrolled use of uPA/plasmin antagonists as tumor angiogenesis inhibitors

Co-location as a catalyst for service innovation : a study of Scottish health and social care

Academic literature and policy on co-location of local public services focus on the cost benefits. Other benefits and outcomes of co-location, including service innovations benefiting users, are under-conceptualized. This paper suggests a framework for evaluating co-location as a learning environment for innovation, drawing on new case studies of five Community Health Partnerships in Scotland charged with more closely coordinating health and social care. We conclude that partnerships using co-location are benefiting from additional service innovations

A qualitative study of patients' views on quality of primary care consultations in Hong Kong and comparison with the UK CARE Measure

<b>Background</b> Patients' priorities and views on quality care are well-documented in Western countries but there is a dearth of research in this area in the East. The aim of the present study was to explore Chinese patients' views on quality of primary care consultations in Hong Kong and to compare these with the items in the CARE measure (a process measure of consultation quality widely used in the UK) in order to assess the potential utility of the CARE measure in a Chinese population.<p></p> <b>Methods</b> Individual semi-structured interviews were conducted on 21 adult patients from 3 different primary care clinics (a public primary healthcare clinic, a University health centre, and a private family physician's clinic). Topics discussed included expectations, experiences, and views about quality of medical consultations. Interviews were typed verbatim, and a thematic approach was taken to identify key issues. These identified issues were then compared with the ten CARE measure items, using a CARE framework: Connecting (Care Measure items 1–3), Assessing (item 4), Responding (items 5,6), and Empowering (items 7–10).<p></p> <b>Results</b> Patients judged doctors in terms of both the process of the consultation and the perceived outcomes. Themes identified that related to the interpersonal process of the consultation fitted well under the CARE framework; Connecting and communicating (18/21 patients), Assessing holistically (10/21 patients), Responding (18/21 patients) and Empowering (19/21 patients). Patients from the public clinic, who were generally of lower socio-economic status, were least likely to expect holistic care or empowerment. Two-thirds of patients also judged doctors on whether they performed an adequate physical examination, and three-quarters on the later outcomes of consultation (in terms of relief or cure and/or side-effects of prescribed drugs).<p></p> <b>Conclusion</b> These findings suggest that Chinese patients in Hong Kong value engaged, empathic primary care doctors and judge the quality of consultations largely on these human skills and the attitudes and values that underpin them, as well as on the perceived outcomes of treatment. The match between themes relating to consultation process and the CARE Measure items suggests utility of this measure in this population, but further quantitative validation is required

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead