Experimental combustor study program

Advanced combustor concepts are evaluated as a means of accommodating possible future broad specification fuels. The three advanced double annular combustor concepts consisted of (1) a concept employing high pressure drop fuel nozzles for improved atomization, (2) a concept with premixing tubes in the main stage, and (3) a concept with the pilot stage on the inside and the main stage on the sideout, which is the reverse of the other two concepts. All of the advanced concepts show promise for reduced sensitivity to fuel hydrogen content. Some hardware problems were encountered, but these problems could be quickly resolved if refinement tests were conducted. The design with the premixing main stage was selected for a parametric test because of its low NOx emissions level, carbon free dome, and very low dome temperatures which were essentially independent of fuel type. The other advanced designs also had low done temperatures. The premixing dome design liner temperatures exhibited less sensitivity to fuel type than did the base-line combustor, although more sensitivity than observed for concept 1. The inner liner hot spot and the observed smoke results for the premixing design suggest that the fuel-air mixture was not as uniform as desired

Experimental evaluation of combustor concepts for burning broad property fuels

A baseline CF6-50 combustor and three advanced combustor designs were evaluated to determine the effects of combustor design on operational characteristics using broad property fuels. Three fuels were used in each test: Jet A, a broad property 13% hydrogen fuel, and a 12% hydrogen fuel blend. Testing was performed in a sector rig at true cruise and simulated takeoff conditions for the CF6-50 engine cycle. The advanced combustors (all double annular, lean dome designs) generally exhibited lower metal temperatures, exhaust emissions, and carbon buildup than the baseline CF6-50 combustor. The sensitivities of emissions and metal temperatures to fuel hydrogen content were also generally lower for the advanced designs. The most promising advanced design used premixing tubes in the main stage. This design was chosen for additional testing in which fuel/air ratio, reference velocity, and fuel flow split were varied

Investigating complex aerodynamic flows with a laser velocimeter

The application of the laser velocimeter in the study of two highly complex aerodynamic flows is discussed. In the first experiment, the laser velocimeter was used with frequency tracking electronics to survey the multiple vortex wake structure behind a model of a large jet transport. The second application is to the study of the induced instantaneous inflow velocities near the blades of a model helicopter rotor; counter-type processing was used in these measurements. In each experiment, the data output channels of these processors were handled in an on-line fashion, including both velocity computations and the plotting of fully reduced data

Broad specification fuels combustion technology program

Design and development efforts to evolve promising aircraft gas turbine combustor configurations for burning broadened-properties fuels were discussed. Design and experimental evaluations of three different combustor concepts in sector combustor rig tests was conducted. The combustor concepts were a state of the art single-annular combustor, a staged double-annular combustor, and a short single-annular combustor with variable geometry to control primary zone stoichiometry. A total of 25 different configurations of the three combustor concepts were evaluated. Testing was conducted over the full range of CF6-80A engine combustor inlet conditions, using four fuels containing between 12% and 14% hydrogen by weight. Good progress was made toward meeting specific program emissions and performance goals with each of the three combustor concepts. The effects of reduced fuel hydrogen content, including increased flame radiation, liner metal temperature, smoke, and NOx emissions were documented. The most significant effect on the baseline combustor was a projected 33% life reduction, for a reduction from 14% to 13% fuel hydrogen content, due to increased liner temperatures

Global wave climate based on the JMA/MRI-AGCM3.2 climate change projection

In this study, global wave climates for present and future climates are simulated by the WAM model,\ud based on wind climate data from the JMA/MRI-AGCM3.2 climate change projection. This study is based on two 6-\ud hourly wind data sets, covering two periods of 1979-2003 (present climate) and 2075-2099 (future climate). These wind\ud data are used to run the WAM model for generating output of wave characteristics. The outputs from each period then\ud were used to study global wave climate in the future. It is found that the wave climate is strongly dependent on latitude,\ud with the largest waves, as well as most significant seasonal variations, located at the mid to high latitude regions. These\ud areas are also where the climate induced changes from present to future climate are most noteworthy. The largest\ud increases of significant wave height of approximately +5%, is experienced in the southern parts of the Indian, Pacific\ud and Atlantic Oceans as well as in the Antarctic Ocean. The largest decreases are of the same order, and limited to the\ud northern Atlantic Ocea

Clean catalytic combustor program

A combustor program was conducted to evolve and to identify the technology needed for, and to establish the credibility of, using combustors with catalytic reactors in modern high-pressure-ratio aircraft turbine engines. Two selected catalytic combustor concepts were designed, fabricated, and evaluated. The combustors were sized for use in the NASA/General Electric Energy Efficient Engine (E3). One of the combustor designs was a basic parallel-staged double-annular combustor. The second design was also a parallel-staged combustor but employed reverse flow cannular catalytic reactors. Subcomponent tests of fuel injection systems and of catalytic reactors for use in the combustion system were also conducted. Very low-level pollutant emissions and excellent combustor performance were achieved. However, it was obvious from these tests that extensive development of fuel/air preparation systems and considerable advancement in the steady-state operating temperature capability of catalytic reactor materials will be required prior to the consideration of catalytic combustion systems for use in high-pressure-ratio aircraft turbine engines

European 'NAFLD Preparedness Index' - Is Europe ready to meet the challenge of fatty liver disease?

Background & Aims: Non-alcoholic fatty liver disease (NAFLD), which is closely associated with obesity, metabolic syndrome, and diabetes, is a highly prevalent emerging condition that can be optimally managed through a multidisciplinary patient centred approach. National preparedness to address NAFLD is essential to ensure that health systems can deliver effective care. We present a NAFLD Preparedness Index for Europe. Methods: In June 2019, data were extracted by expert groups from 29 countries to complete a 41-item questionnaire about NAFLD. Questions were classified into 4 categories: policies/civil society (9 questions), guidelines (16 questions), epidemiology (4 questions), and care management (12 questions). Based on the responses, national preparedness for each indicator was classified into low, middle, or high-levels. We then applied a multiple correspondence analysis to obtain a standardised preparedness score for each country ranging from 0 to 100. Results: The analysis estimated a summary factor that explained 71.3% of the variation in the dataset. No countries were found to have yet attained a high-level of preparedness. Currently, the UK (75.5) scored best, although falling within the mid level preparedness band, followed by Spain (56.2), and Denmark (43.4), whereas Luxembourg and Ireland were the lowest scoring countries with a score of 4.9. Only Spain scored highly in the epidemiology indicator category, whereas the UK was the only country that scored highly for care management. Conclusions: The NAFLD Preparedness Index indicates substantial variation between countries’ readiness to address NAFLD. Notably, even those countries that score relatively highly exhibit deficiencies in key domains, suggesting that structural changes are needed to optimise NAFLD management and ensure effective public health approaches are in place. Lay summary: Non-alcoholic fatty liver disease (NAFLD), which is closely associated with obesity, metabolic syndrome, and diabetes, is a highly prevalent condition that can be optimally managed through a multidisciplinary patient-centred approach. National preparedness to address NAFLD is essential to allow for effective public health measures aimed at preventing disease while also ensuring that health systems can deliver effective care to affected populations. This study defined preparedness as having adequate policies and civil society engagement, guidelines, epidemiology, and care management. NAFLD preparedness was found to be deficient in all 29 countries studied, with great variation among the countries and the 4 categories studied

Effect of resting pressure on the estimate of cerebrospinal fluid outflow conductance

<p>Abstract</p> <p>Background</p> <p>A lumbar infusion test is commonly used as a predictive test for patients with normal pressure hydrocephalus and for evaluation of cerebrospinal fluid (CSF) shunt function. Different infusion protocols can be used to estimate the outflow conductance (<it>C</it>_out) or its reciprocal the outflow resistance (<it>R</it>_out), with or without using the baseline resting pressure, <it>P</it>_r. Both from a basic physiological research and a clinical perspective, it is important to understand the limitations of the model on which infusion tests are based. By estimating <it>C</it>_out using two different analyses, with or without <it>P</it>_r, the limitations could be explored. The aim of this study was to compare the <it>C</it>_out estimates, and investigate what effect <it>P</it>_rhad on the results.</p> <p>Methods</p> <p>Sixty-three patients that underwent a constant pressure infusion protocol as part of their preoperative evaluation for normal pressure hydrocephalus, were included (age 70.3 ± 10.8 years (mean ± SD)). The analysis was performed without (<it>C</it>_{excl Pr}) and with (<it>C</it>_{incl Pr}) P_r. The estimates were compared using Bland-Altman plots and paired sample <it>t</it>-tests (<it>p </it>< 0.05 considered significant).</p> <p>Results</p> <p>Mean <it>C</it>_out for the 63 patients was: <it>C</it>_{excl Pr}= 7.0 ± 4.0 (mean ± SD) μl/(s kPa) and <it>C</it>_{incl Pr} = 9.1 ± 4.3 μl/(s kPa) and <it>R</it>_out was 19.0 ± 9.2 and 17.7 ± 11.3 mmHg/ml/min, respectively. There was a positive correlation between methods (r = 0.79, n = 63, <it>p </it>< 0.01). The difference, Δ<it>C</it>_out= -2.1 ± 2.7 μl/(s kPa) between methods was significant (<it>p </it>< 0.01) and Δ<it>R</it>_outwas 1.2 ± 8.8 mmHg/ml/min). The Bland-Altman plot visualized that the variation around the mean difference was similar all through the range of measured values and there was no correlation between Δ<it>C</it>_outand <it>C</it>_out.</p> <p>Conclusions</p> <p>The difference between <it>C</it>_outestimates, obtained from analyses with or without <it>P</it>_r, needs to be taken into consideration when comparing results from studies using different infusion test protocols. The study suggests variation in CSF formation rate, variation in venous pressure or a pressure dependent <it>C</it>_outas possible causes for the deviation from the CSF absorption model seen in some patients.</p

A cross-sectional study of the public health response to non-alcoholic fatty liver disease in Europe

Background &amp; Aims: Non-alcoholic fatty liver disease (NAFLD) is a growing public health problem worldwide and has become an important field of biomedical inquiry. We aimed to determine whether European countries have mounted an adequate public health response to NAFLD and non-alcoholic steatohepatitis (NASH). Methods: In 2018 and 2019, NAFLD experts in 29 European countries completed an English-language survey on policies, guidelines, awareness, monitoring, diagnosis and clinical assessment in their country. The data were compiled, quality checked against existing official documents and reported descriptively. Results: None of the 29 participating countries had written strategies or action plans for NAFLD. Two countries (7%) had mentions of NAFLD or NASH in related existing strategies (obesity and alcohol). Ten (34%) reported having national clinical guidelines specifically addressing NAFLD and, upon diagnosis, all included recommendations for the assessment of diabetes and liver cirrhosis. Eleven countries (38%) recommended screening for NAFLD in all patients with either diabetes, obesity and/or metabolic syndrome. Five countries (17%) had referral algorithms for follow-up and specialist referral in primary care, and 7 (24%) reported structured lifestyle programmes aimed at NAFLD. Seven (24%) had funded awareness campaigns that specifically included prevention of liver disease. Four countries (14%) reported having civil society groups which address NAFLD and 3 countries (10%) had national registries that include NAFLD. Conclusions: We found that a comprehensive public health response to NAFLD is lacking in the surveyed European countries. This includes policy in the form of a strategy, clinical guidelines, awareness campaigns, civil society involvement, and health systems organisation, including registries. Lay summary: We conducted a survey on non-alcoholic fatty liver disease with experts in European countries, coupled with data extracted from official documents on policies, clinical guidelines, awareness, and monitoring. We found a general lack of national policies, awareness campaigns and civil society involvement, and few epidemiological registries