3D shape optimisation of a low-pressure turbine stage

The possibility of reducing the flow losses in low-pressure turbine stage has been investigated in an iterative process using a novel hybrid optimisation algorithm. Values of the maximised objective function that is isentropic efficiency are found from 3D RANS computation of the flowpath geometry, which was being changed during the optimisation process. To secure the global flow conditions, the constraints have been imposed on the mass flow rate and reaction. Among the optimised parameters are stator and rotor twist angles, stator sweep and lean, both straight and compound. Blade profiles remained unchanged during the optimisation. A new hybrid stochastic-deterministic algorithm was used for the optimisation of the flowpath. In the proposed algorithm, the bat algorithm was combined with the direct search method of Nelder-Mead in order to refine the best obtained solution from the standard bat algorithm. The method was tested on a wide variety of well-known test functions. Also, the results of the optimisation of the other stochastic and deterministic methods were compared and discussed. The optimisation gives new 3D-stage designs with increased efficiency comparing to the original design.This work was supported by The National Science Centre, Grant No. 2015/17/N/ST8/01782

ORC turbine design

Workshop byl částečně podpořen projektem CZ.1.07/2.3.00/20.0139. Tento projekt je spolufinancován Evropským sociálním fondem a státním rozpočtem České republiky

ORC turbine design

Workshop byl částečně podpořen projektem CZ.1.07/2.3.00/20.0139. Tento projekt je spolufinancován Evropským sociálním fondem a státním rozpočtem České republiky

Development of the 500 kW and 1 MW ORC turbine flow parts

There paper presents two types of developed ORC turbines. The silica oil (MDM) is used as the working media. Proposed turbines are developed for electric power in 500 kW and 1 MW. For the designing of that turbines there were only one geometric constraint: the minimum height of the blade – 20 mm. The final 3D calculations of all turbine stages are provided with accounting the real properties of working media. Gasdynamic efficiency of the developed turbine flow parts is adequate for the such type of power machines.Рассмотрены несколько вариантов проточных частей осевых турбин мощностью 500 кВт и 1 МВт для когенерационной установки, использующей в качестве рабочего тела силиконовое масло (MDM). Единственным геометрическим ограничением для проектирования этих турбин было минимальная высота лопатки – 20 мм. Окончательные трехмерные расчеты всех ступеней турбины проведены с учетом реальных свойств рабочего тела на основе модифицированного уравнения состояния Бенедикта-Вебба-Рубина. Газодинамическая эффективность разработанных проточных частей турбин удовлетворяет требованиям, предъявляемым к энергетическим машинам подобного рода.Розглянуто декілька варіантів проточних частин осьових турбін потужністю 50 кВт та 1 МВт для когенераційної установки, що використовує як робоче тіло силіконове масло (MDM). Єдиним геометричним обмеженням для проектування цих турбін було мінімальна висота лопатки – 20 мм. Остаточні тривимірні розрахунки всіх ступенів турбіни проведено з урахуванням реальних властивостей робочого тіла на основі модифікованого рівняння стану Бенедикта-Вебба-Рубіна. Газодинамічна ефективність розроблених проточних частин турбін задовольняє вимоги, що ставляться до енергетичних машин подібного роду

Analytical method for profiling of radial stator blades of turbine stages

The method of analytical profiling of radial stator blades is considered, which in combination with numerical modelling of three-dimensional viscous flows allows us to improve the efficiency of the flow part of high-loaded centripetal turbines. The profile of radial blades is determined in a curvilinear coordinate system and consists of the trailing and leading edges, and also of suction and pressure sides described by polynomial curves of the 5th and 4th order, respectively. Thanks to this method, highly efficient radial stator blades of high-loaded stages can be designed. The special form of blade-to-blade channels allows us to obtain a low level of profile and trailing edge losses, as well as low supersonic and shock wave losses of kinetic energy. Three variants of turbines with different types of stator blade profiles are considered: the profile developed using a standard method for axial blades; the “half-drop” profile and the profile developed using the proposed method. For the stator profile developed in this paper, the stator kinetic energy losses related to the enthalpy drop in the stage were decreased by 2,2% compared to the profile of a classic form, and by 1,1% compared to the “half-drop” profile. Using of the high-loaded stage with a new type of stator blade profile allowed us to significantly improve the aerodynamic characteristics of the flow part in the whole stage.Рассмотрен метод аналитического профилирования радиальных лопаток направляющих аппаратов, использование которого в сочетании с численным моделированием трехмерных вязких течений позволяет повысить эффективность проточных частей высоконагргженных центростремительных турбин.Запропоновано аналітичний метод побудови профілів радіальних лопаток турбінних ступенів. Профіль задається в криволінійній системі координат, складається з вхідної та вихідної кромок, а також спинки і коритця, описаних кривими 5-го та 4-го порядків відповідно. Розглянуто приклад високонавантаженого радіально-осьового ступеня з профілем направляючого апарата нового типу, застосування якого дозволило істотно поліпшити аеродинамічні характеристики проточної частини

Viral Resistance in Hepatitis B: Prevalence and Management

Hepatitis B is a DNA virus affecting hundreds of millions of individuals worldwide. As the clinical sequelae of cirrhosis and hepatocellular cancer are increasingly recognized to be related to viral levels, the impetus increases to offer treatment to those previously not treated. With the development of more robust antivirals with reasonable safety profiles, long-term treatment is becoming more common. The oral nucleos(t)ide analogs have become the preferred first-line therapies for most genotypes of hepatitis B. Five are now available, all with different potencies and resistance profiles. Long-term data spanning several years are now available for most compounds in this arena. This article focuses on the common natural variants and those secondary to nucleos(t)ide therapy, as well as diagnostic methods to detect resistance

Current Antiviral Therapy of Chronic Hepatitis B: Efficacy and Safety

The treatment of chronic hepatitis B is in constant evolution. Interferon, the first agent licensed for chronic hepatitis B treatment, has been superseded by the growing popularity of nucleoside/nucleotide analogues (NA). However, resistance to these agents is a major challenge. Newer NAs, such as entecavir and tenofovir dipivoxil fumarate, have very low resistance rates and favorable safety profiles. Long-term use of these agents can effectively suppress hepatitis B virus DNA, leading to decrease in incidence of hepatitic flares, as well as in the development of cirrhosis and hepatocellular carcinoma. The efficacy and safety of various antiviral agents is discussed in this review

The histology of ovarian cancer: worldwide distribution and implications for international survival comparisons (CONCORD-2)

Objective Ovarian cancers comprise several histologically distinct tumour groups with widely different prognosis. We aimed to describe the worldwide distribution of ovarian cancer histology and to understand what role this may play in international variation in survival. Methods The CONCORD programme is the largest population-based study of global trends in cancer survival. Data on 681,759 women diagnosed during 1995â\u80\u932009 with cancer of the ovary, fallopian tube, peritoneum and retroperitonum in 51 countries were included. We categorised ovarian tumours into six histological groups, and explored the worldwide distribution of histology. Results During 2005â\u80\u932009, type II epithelial tumours were the most common. The proportion was much higher in Oceania (73.1%), North America (73.0%) and Europe (72.6%) than in Central and South America (65.7%) and Asia (56.1%). By contrast, type I epithelial tumours were more common in Asia (32.5%), compared with only 19.4% in North America. From 1995 to 2009, the proportion of type II epithelial tumours increased from 68.6% to 71.1%, while the proportion of type I epithelial tumours fell from 23.8% to 21.2%. The proportions of germ cell tumours, sex cord-stromal tumours, other specific non-epithelial tumours and tumours of non-specific morphology all remained stable over time. Conclusions The distribution of ovarian cancer histology varies widely worldwide. Type I epithelial, germ cell and sex cord-stromal tumours are generally associated with higher survival than type II tumours, so the proportion of these tumours may influence survival estimates for all ovarian cancers combined. The distribution of histological groups should be considered when comparing survival between countries and regions

Worldwide comparison of survival from childhood leukaemia for 1995–2009, by subtype, age, and sex (CONCORD-2): a population-based study of individual data for 89 828 children from 198 registries in 53 countries

Background Global inequalities in access to health care are reflected in differences in cancer survival. The CONCORD programme was designed to assess worldwide differences and trends in population-based cancer survival. In this population-based study, we aimed to estimate survival inequalities globally for several subtypes of childhood leukaemia. Methods Cancer registries participating in CONCORD were asked to submit tumour registrations for all children aged 0-14 years who were diagnosed with leukaemia between Jan 1, 1995, and Dec 31, 2009, and followed up until Dec 31, 2009. Haematological malignancies were defined by morphology codes in the International Classification of Diseases for Oncology, third revision. We excluded data from registries from which the data were judged to be less reliable, or included only lymphomas, and data from countries in which data for fewer than ten children were available for analysis. We also excluded records because of a missing date of birth, diagnosis, or last known vital status. We estimated 5-year net survival (ie, the probability of surviving at least 5 years after diagnosis, after controlling for deaths from other causes [background mortality]) for children by calendar period of diagnosis (1995-99, 2000-04, and 2005-09), sex, and age at diagnosis (< 1, 1-4, 5-9, and 10-14 years, inclusive) using appropriate life tables. We estimated age-standardised net survival for international comparison of survival trends for precursor-cell acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia (AML). Findings We analysed data from 89 828 children from 198 registries in 53 countries. During 1995-99, 5-year agestandardised net survival for all lymphoid leukaemias combined ranged from 10.6% (95% CI 3.1-18.2) in the Chinese registries to 86.8% (81.6-92.0) in Austria. International differences in 5-year survival for childhood leukaemia were still large as recently as 2005-09, when age-standardised survival for lymphoid leukaemias ranged from 52.4% (95% CI 42.8-61.9) in Cali, Colombia, to 91.6% (89.5-93.6) in the German registries, and for AML ranged from 33.3% (18.9-47.7) in Bulgaria to 78.2% (72.0-84.3) in German registries. Survival from precursor-cell ALL was very close to that of all lymphoid leukaemias combined, with similar variation. In most countries, survival from AML improved more than survival from ALL between 2000-04 and 2005-09. Survival for each type of leukaemia varied markedly with age: survival was highest for children aged 1-4 and 5-9 years, and lowest for infants (younger than 1 year). There was no systematic difference in survival between boys and girls. Interpretation Global inequalities in survival from childhood leukaemia have narrowed with time but remain very wide for both ALL and AML. These results provide useful information for health policy makers on the effectiveness of health-care systems and for cancer policy makers to reduce inequalities in childhood survival