Full Admission Research Articles

Plasma from patients undergoing allogeneic hematopoietic stem cell transplantation promotes NETOSIS in vitro and correlates with inflammatory parameters and clinical severity.

NETosis, the mechanism by which neutrophils release extracellular traps (NETs), is closely related to inflammation. During the allogeneic hematopoietic stem cell transplantation (allo-HSCT), different stimuli can induce NETs formation. Inflammation and endothelial injury have been associated with acute graft-versus-host disease (aGVHD) and complications after allo-HSCT. We focus on the study of NETosis and its relation with cytokines, hematological and biochemical parameters and clinical outcomes before, during and after allo-HSCT. We evaluate the capacity of plasma samples from allo-HSCT patients to induce NETosis, in a cell culture model. Plasma samples from patients undergoing allo-HSCT had a stronger higher NETs induction capacity (NETsIC) than plasma from healthy donors throughout the transplantation process. An optimal cut-off value by ROC analysis was established to discriminate between patients whose plasma triggered NETosis (NETs+IC group) and those who did not (NETs-IC group). Prior to conditioning treatment, the capacity of plasma samples to trigger NETosis was significantly correlated with the Endothelial Activation and Stress Index (EASIX) score. At day 5 after transplant, patients with a positive NETsIC had higher interleukin (IL)-6 and C-reactive protein (CRP) levels and also a higher Modified EASIX score (M-EASIX) than patients with a negative NETsIC. EASIX and M-EASIX scores seek to determine inflammation and endothelium damage, therefore it could indicate a heightened immune response and inflammation in the group of patients with a positive NETsIC. Cytokine levels, specifically IL-8 and IL-6, significantly increased after allo-HSCT with peak levels reached on day 10 after graft infusion. Only, IL-10 and IL-6 levels were significantly higher in patients with a positive NETsIC. In our small cohort, higher IL-6 and IL-8 levels were related to early severe complications (before day 15 after transplant). Although early complications were not related to NETosis by itself, NETosis could predict overall non-specific but clinically significant complications during the full patient admission. In summary, NETosis can be directly induced by plasma from allo-HSCT patients and NETsIC was associated with clinical indicators of disease severity, cytokines levels and inflammatory markers.

A comparison study of loss generation between twin-entry and double-entry volutes of nozzled mixed-flow turbines

Turbochargers whose turbines contain two-entry volutes are advantageous as they help to improve the low-end torque and transient performance of internal combustion engines. Two types of two-entry turbines are applied currently in turbocharging, which are the twin-entry turbine (TE) and the double-entry turbine (DE). To develop more efficient turbocharged engines, a further understanding of the performance characteristics and loss mechanisms of two types of two-entry turbines is needed. However, few investigations have been carried out to directly compare these two types of turbines. Through an experimentally validated numerical method, this paper compares the performance and detailed flow mechanism of twin/double-entry turbines with the same nozzled mixed-flow rotor. The 3D simulation is validated against the measured performance as well as the flow field carried out on test rigs. Results show that the performance of the double-entry turbine is notably superior over that of the twin-entry counterpart although their peak swallowing capacities and efficiencies are at a similar level. In particular, the efficiency and swallowing capacity deteriorate more gently for the double-entry turbine as operational condition deviates from full admission. It was revealed via the loss breakdown of turbine components that, the volute and the nozzle are the main contributors to the performance discrepancy between the two turbines. Specifically, the loss in the twin-entry volute is higher than that of the double-entry one, especially in the case of partial admissions. Flow analysis shows that the flow is mixed strongly in the vicinity of the limb divider of the twin-entry volute in the whole circumference, while it only concentrates in the vicinity of the tongues for the double-entry turbine. Therefore, a higher entropy-rise is generated in the twin-entry volute. Moreover, the mixing flow attenuates the flow distortion in the nozzle and produces more uniform entropy rise in the nozzle for the twin-entry configuration. On the other hand, flow distortion is well preserved in nozzle for the double-entry turbine, thus regions with high entropy-rise appear in a portion of nozzle passages. Consequently, a higher loss is produced in the volute and the nozzle for the twin-entry turbine. This paper provides knowledge of performance characteristics of two two-entry turbines and sheds light on the performance improvement of two-entry turbines.

The effects of dual-strain probiotics on the weight gain in premature neonates of Kabul City: A randomized clinical trial

BackgroundPrematurity is prevalent worldwide and accounts for the leading cause of neonatal death. Preterm neonates face numerous challenges, including slow weight gain, prolonged hospital stays, and high mortality. Dual-strain probiotics containing Bifidobacterium bifidum and Clostridium butyricum can manage such complications of prematurity. Therefore, the present study was conducted to evaluate the effectiveness of dual-strain probiotics consisting of Bifidobacterium bifidum and Clostridium butyricum on the weight gain of preterm neonates in Kabul City. MethodsThis randomized clinical trial was conducted at the Neonatal Units of Malalai Maternity and Maiwand Teaching Hospitals in Kabul City. Finally, 84 preterm neonates were assessed for the effects of dual-strain probiotics. The clinical parameters were daily weight gain and the risks of feeding intolerance and neonatal mortality. Statistical analysis was performed by SPSS 26. ResultsForty-two premature neonates in the probiotics group and another forty-two preterm babies in the control group were investigated. In the probiotic group, 250 mg or 25 × 108 CFU of dual-strain probiotics dissolved in 1–3 ml milk were given twice daily for three weeks. At the time of intervention, the preterm neonates in the probiotics versus control group had a mean age of (7 ± 3.3 vs 6.8 ± 3.3 days; P = 0.69), weight of (1497.5 ± 272 vs 1483.3 ± 271 g; P = 0.8) and gestational age of (33.6 ± 2 vs 33 ± 2.4 weeks; p = 0.31). Gender distribution in the probiotics group was (boys 54.8%, girls 45.2%) and in the control group it was (boys 50%, girl 50%). The premature newborns in the probiotics versus control group had a higher mean daily weight gain (15.5 ± 9.4 vs 10 ± 7.9 g; P = 0.001), lower mean age to reach full enteral feeds (8.74 ± 3.08 vs 10.81 ± 3.43 days, P = 0.005) and lower mean hospital stays (10.02 ± 4.68 vs 12.81 ± 4.86 days, P = 0.009) . The risk ratios of feeding intolerance and mortality during the hospital stays were (RR=0.59, P = 0.71) and (RR=0.67, P = 0.5) in probiotics and non-probiotics groups respectively. ConclusionDual-strain probiotics consisting of Bifidobacterium bifidum and Clostridium butyricum significantly improved the daily weight gain, and decreased the time to full enteral feeding and admission days for premature neonates.

노인복지주택의 공급 활성화 방안에 관한 연구

1. CONTENTS (1) RESEARCH OBJECTIVES The purpose of this study was to find ways to revitalize the supply of welfare housing for the elderly by identifying the current situation and problems in which welfare housing for the elderly have been supplied sluggishly and supplied mainly for the high-income class. (2) RESEARCH METHOD As a research method, the supply of systematic private construction rental housing and the supply case of elderly housing in major developed countries were first compared and analyzed based on previous research papers and various literature. In addition, various statistical data at home and abroad were used here. (3) RESEARCH FINDINGS As a result of the study, the reason for the sluggish supply of welfare housing for the elderly and the high-priced supply were that the market principle of supply and demand in the elderly housing market has not worked properly. 2. RESULTS As a way to improve and revitalize this, first, it is to classify and define elderly welfare housing defined as facilities into housing type and facility type, and to prepare detailed regulations on the supply, installation, operation, and management of elderly welfare housing. Second, it is to improve the system to guarantee the return of full admission deposits and secure land ownership. Third, the government or local governments supply land cheaply to social welfare corporations, medical care, and religious corporations to improve the profit structure of suppliers, while allowing installation operators to pursue the public interest of welfare for the elderly. Fourth, local governments develop and distribute programs to introduce a facility operation evaluation system, train professional operation managers, and supervise facility operation.

Comparison of Secondary Flow Characteristics in Mixed-Flow Turbine between Nozzleless and Symmetric Nozzle Vane Angles under Steady-State Flow at Full Admission

In industrial applications, radial or mixed-flow turbines are frequently used in energy recovery systems, small turbines for producing power, and turbochargers. The implementation of radial or mixed-flow turbines helps to maintain high efficiency at a large range of pressure ratios by reducing the overall turbine losses and secondary flow losses. Numerous findings on secondary flow development research adopting double-entry turbines can be obtained in the public domain, except asymmetric volute, which is less well-researched. The focus of the present work is to investigate the evolution of secondary flows and their losses in a mixed-flow turbine used in an asymmetric volute turbine, by employing an experimentally validated three-dimensional computational fluid dynamics (CFD). The flow topology is analyzed to explain the formation and evolution of flow separations at the pressure, suction, and hub surfaces. As the opening angle of the nozzle vane increases, the incidence angle falls into the positive range while the maximum pressure difference between the shroud and hub decreases by about 40%. The results also show that the development of secondary flow accounts for the majority of losses and induced the centrifugal pressure head influence. The presence of symmetric nozzle vanes in both large and small scrolls is also found to have a significant detrimental effect on the turbine efficiency, which is 4% lower than the nozzleless case. Furthermore, significant flow separation is observed in the symmetrical nozzle vane configuration as opposed to that of nozzleless. In addition, the centrifugal pressure head indicated by the maximum pressure difference between the hub and shroud influences the overall turbine efficiency, as the symmetrical nozzle vane arrangement is introduced with two different turbine rotational speeds of 30 K rpm and 48 K rpm.

Blade Vibration Analysis for Radial Turbine Featuring a Multi-Channel Casing Design

Abstract Multi-channel casing (MC) shows promising results in controlling the performance of the radial turbines. It has neither movable parts nor complicated control mechanisms therefore it withstands higher thermal loads compared to the commonly used control systems such as the Variable Geometry Turbine (VGT). This advantage makes the MC applicable for a wider range of applications which is difficult to be covered with the common control systems. Replacing the traditional spiral casing with the MC affects the blade's vibration behavior. First, a 3D unsteady computational fluid dynamic (CFD) simulation is performed to investigate the influence of using MC on the turbine flow field for both full and partial admission operation. Second, a forced response analysis is performed based on the CFD result to calculate the blade vibration amplitude at different resonance crossings. Finally, an MC is manufactured and tested experimentally to validate the numerical study. The results show that ignoring the casing replacement effect on the blade vibration during the MC design phase led to a high vibration amplitude and consequently causes high cycle fatigue.

HCF and LCF Analysis of a Generic Full Admission Turbine Blade

A numerical turbine-blade fatigue-life analysis method is suggested. This method comprises a stationary thermal 3D finite element (FE) analysis of the hot run for the combined high-cycle fatigue (HCF) and creep analysis, and a follow-on (one-way coupled) quasi-stationary structural 3D FE analysis (including six load steps) of a single and two half turbine blades and the related disk and rotor section and a (modified Goodman equation based) post-processing fatigue life analysis for the highest HCF-loaded point of the turbine blade. For the low-cycle fatigue (LCF) analysis, this includes a transient thermal 3D FE analysis of two full loading cycles, a follow-on (one-way coupled) quasi-stationary structural 3D finite element analysis of a single and two half turbine blades and the related disk and rotor section and a (modified-Langer-equation-based) post-processing fatigue life analysis approach for the highest LCF-loaded point of the turbine blade. Finally, this approach is demonstrated by the numerical HCF, LCF and creep analysis of a generic turbine blade of the first rotor row of a full admission hydrogen turbo pump of a 1 MN thrust class gas generator LOX-LH2 liquid rocket engine (LRE). For this numerical example, the LCF loading turned out to be dominant. Creep turned out to be negligible.

Interrogating the Myths of Education: Dorothy Bryant'sElla Price's JournalandMiss Giardino

Interrogating the Myths of Education: Dorothy Bryant's<i>Ella Price's Journal</i>and<i>Miss Giardino</i>

Assessment of a twin-entry turbine efficiency model including momentum exchange between branches

Radial twin-entry turbines standard maps have limited data available for fitting model parameters since they usually provide information only at full and partial admission conditions. However, twin-entry turbines’ most common operation is at unequal admission conditions. A new losses-based efficiency model has been developed that takes into account the behaviour of the twin-entry turbines at unequal admission conditions considering the different losses produced in each of its parts to improve the model predictions in these conditions. The model is validated with experimental measurements of the whole range of admission conditions, and all the model parameters needed are fitted. Moreover, the model’s accuracy is compared with empirical and commercial models using a limited amount of data instead of the whole measured map, obtaining reasonable extrapolations and improving the results provided by the other models at unequal admission conditions.

Hospital-Level Care at Home for Patients With Acute Respiratory Disease: A Descriptive Analysis

Home hospital (HH) care is hospital-level substitutive care delivered at home for acutely ill patients who traditionally would be cared for in the hospital. Despite HH care programs operating successfully for years and scientific evidence of similar or better outcomes compared with bricks-and-mortar care, HH care outcomes in the United States for respiratory disease have not been evaluated. Do outcomes differ between patients admitted to HH care with acute respiratory illness vsthose with other acute general medical conditions? This was a retrospective evaluation of prospectively collected data of patients admitted to HH care (2017-2021). We compared patients requiring admission with respiratory disease (asthma exacerbation [26%], acute exacerbation of COPD [33%], and non-COVID-19 pneumonia [41%]) to all other patients admitted to HH care. During HH care, patients received two nurse and one physician visit daily, IV medications, advanced respiratory therapies, and continuous heart and respiratory rate monitoring. Main outcomes were acute and postacute health-care use and safety. We analyzed 1,031 patients; 24%were admitted for respiratory disease. Patients with and without respiratory disease were similar: mean age, 68 ± 17 years, 62%women, and 48%White. Patients with respiratory more often were active smokers (21%vs9%; P< .001). Eighty percent of patients showed an FEV1 to FVC ratio of≤ 70; 28%showed a severe or very severe obstructive pattern (n= 118). During HH care, patients with respiratory disease showed less health-care use: length of stay (mean, 3.4 vs4.6days), laboratory orders (median, 0 vs2), IV medication (43%vs73%), and specialist consultation (2%vs7%; P< .001 for all). Ninety-six percent of patients completed the full admission at home with no mortality in the respiratory group. Within 30days of discharge, both groups showed similar readmission, ED presentation, and mortality rates. HH care is as safe and effective for patients with acute respiratory disease as for those with other acute general medical conditions. If scaled, it can generate significant high-value capacity for health systems and communities, with opportunities to advance the complexity of care delivered.

Zagadnienie sądów pokoju w pracach Sejmu II Rzeczypospolitej w świetle wniosków i interpelacji poselskich

The Issue of the Office of Justice of the Peace in the Work of the Sejm of the Second Polish Republic in Light of Parliamentary Bills and Interpellations The justices of the peace were one of the forms of society’s participation in the judiciary in the Second Polish Republic. This institution was inherited from the former partitioning states and did not exist throughout the country. Justices of the peace were provided for by the Act’s provisions amending the Law on the System of Ordinary Courts, but its requirements have been never implemented. Justices of the peace ended their activity in 1929, but their formal liquidation only occurred in 1938. In interwar Poland justices of the peace were not a form of public participation in the judiciary. They were in fact judges with significantly lower substantive competencies than professional judges. Contrary to the provisions of the Constitution of 1921, justices of the peace were not elected by popular vote. The article deals with the extensive debates that took place in the Sejm regarding the selection of justices of the peace, and their role in the judiciary of the Second Republic of Poland, especially in its first period (1919–1928), when it was a problem of great interest to parliamentarians. This is evidenced by the numerous interpellations and parliamentary bills that the parliamentarians submitted, which the author analyses and quotes. On this basis, he concludes that the institution of justice of the peace was not supported by deputies, especially from among the agrarian and socialist parties. Often, justices of the peace were (in interpellations) accused of corruption, nepotism, and incompetence. The solution to this problem was seen in the full admission of society to participate in the judiciary, e.g. in the forms of justices of the peace, jury courts and lay judges.

Risk Factors for Relapse in People with Severe Mental Disorders during the COVID-19 Pandemic: A Multicenter Retrospective Study.

Background: Evidence suggests that different variables associated with the COVID-19 pandemic may increase the risk of relapse in people with Severe Mental Disorders (SMDs). However, no studies have yet looked closely at the different risk factors involved to determine their influence on the worsening of these patients’ illnesses. Objective: To analyze which variables related to the COVID-19 pandemic have increased the risk of relapse in patients with SMDs. Method: A multicenter retrospective cohort study in which data were collected from 270 patients with mental disorders who had been under follow-up in day hospitals during the year 2020. Results: The proportion of full mental health inpatient admissions was significantly higher in those who lost their employment (40.7% vs. 18.1%; p = 0.01), in those who were not receiving psychotherapy interventions (33.9% vs. 16.6%; p = 0.006), and in those who were not receiving occupational therapy (25.7% vs. 13.6%: p = 0.013). Significant associations were detected between urgent mental health consultations, the number of COVID-19 symptoms (B = 0.274; p = 0.02), and the low-income group (1.2424 vs. 0.4583; p = 0.018). Conclusions: COVID-19 symptoms and certain consequences of the pandemic, such as loss of employment, economic hardship, and loss of interventions, have brought about clinical worsening in people with SMDs. Knowledge of these factors is important for health-related decision-making in future outbreaks or pandemics.

Reducing Biofilm Infections in Burn Patients' Wounds and Biofilms on Surfaces in Hospitals, Medical Facilities and Medical Equipment to Improve Burn Care: A Systematic Review.

Biofilms in burns are major problems: bacterial communities rapidly develop antibiotic resistance, and 60% of burn mortality is attributed to biofilms. Key pathogens are Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus, and multidrug-resistant Acinetobacter baumanii. Purpose: identify current and novel interventions to reduce biofilms on patients’ burns and hospital surfaces and equipment. Medline and Embase were searched without date or language limits, and 31 possible interventions were prioritised: phages, nano-silver, AgSD-NLs@Cur, Acticoat and Mepilex silver, acetic acid, graphene-metal combinations, CuCo2SO4 nanoparticles, Chlorhexidene acetate nanoemulsion, a hydrogel with moxifloxacin, carbomer, Chitosan and Boswellia, LED light therapy with nano-emodin or antimicrobial blue light + Carvacrol to release reactive oxygen species, mannosidase + trypsin, NCK-10 (a napthalene compound with a decyl chain), antimicrobial peptide PV3 (includes two snake venoms), and polypeptides P03 and PL2. Most interventions aimed to penetrate cell membranes and reported significant reductions in biofilms in cfu/mL or biofilm mass or antibiotic minimal inhibitory concentrations or bacterial expression of virulence or quorum sensing genes. Scanning electron microscopy identified important changes in bacterial surfaces. Patients with biofilms need isolating and treating before full admission to hospital. Cleaning and disinfecting needs to include identifying biofilms on keyboards, tablets, cell phones, medical equipment (especially endoscopes), sinks, drains, and kitchens.

Numerical investigation of partial admission losses in radial inflow turbines

Radial inflow turbines are taken as potential power conversion units for many power cycles where full admission is employed. The partial admission turbine is usually selected for small-scale power output due to the reduced mass flow rate and machining constraints, resulting in substantial low efficiency. The flow characteristics in different partial admission ratios are still unknown. The suitability of existing correlations for partial admission losses is also questionable since the partial admission loss model is usually established upon experimental results of axial turbines. In this paper, the three-dimensional computational fluid dynamics method is utilized to investigate flow characteristics within partial admission radial inflow turbines. The partial admission ratio varies from 0.05 to 0.9. The numerical loss break-down is then performed and compared against existing empirical correlations in literature, where the partial admission ratio from 0.158 to 0.526 is of interest. The suitable partial admission loss model (Stuter & Traupel windage loss model and Stenning expansion loss model) is finally selected and successfully employed to design partial admission radial inflow turbines preliminarily. The relative error of 3% is attained by comparing mean-line and numerical results. This paper provides insight into the partial admission loss mechanism within radial inflow turbines.

Epidemiology of healthcare-associated infection reported from a hospital-wide incidence study: considerations for infection prevention and control planning

The measure of disease frequency most widely used to report healthcare-associated infection (HAI) is the point-prevalence survey. Incidence studies are rarely performed due to time and cost constraints; they show which patients are affected by HAI, when and where, and inform planning and design of infection prevention and control (IPC) measures. To determine the epidemiology of HAI within a general and a teaching hospital in Scotland. A prospective observational incidence study was undertaken for one year from April 2018 using data collected as part of the Evaluation of Cost of Nosocomial Infection (ECONI) study. A novel, robust approach was undertaken, using record linkage to national administrative data to provide full admission and discharge information. Cases were recorded if they met international HAI definitions. Incidence of HAI for the combined hospitals was 250 HAI cases per 100,000 acute occupied bed-days (AOBD). Highest frequency was in urinary tract (51.2 per 100,000 AOBD), bloodstream (44.7), and lower respiratory tract infection (42.2). The most frequently reported organisms were Escherichia coli, Staphylococcus aureus, and norovirus. Incidence of HAI was higher in older people and emergency cases. There was an increase in the rate of HAI in summer months (pneumonia, respiratory, surgical, and gastrointestinal infection) and in winter months norovirus gastrointestinal infection (P < 0.0001). The highest incidence specialties were intensive care, renal medicine, and cardiothoracic surgery. HAI occurred at a median of 9 days (interquartile range: 4-19) after admission. Incidence data were extrapolated to provide an annual national estimate of HAI in NHS Scotland of 7437 (95% confidence interval: 7021-7849) cases. This study provides a unique overview of incidence of HAI and identifies the burden of HAI at the national level for the first time. Understanding the incidence in different clinical settings, at different times, will allow targeting of IPC measures to those patients who would benefit the most.

Predicting Prolonged Hospitalization and Supplemental Oxygenation in Patients with COVID-19 Infection from Ambulatory Chest Radiographs using Deep Learning

Rationale and ObjectivesThe clinical prognosis of outpatients with coronavirus disease 2019 (COVID-19) remains difficult to predict, with outcomes including asymptomatic, hospitalization, intubation, and death. Here we determined the prognostic value of an outpatient chest radiograph, together with an ensemble of deep learning algorithms predicting comorbidities and airspace disease to identify patients at a higher risk of hospitalization from COVID-19 infection.Materials and MethodsThis retrospective study included outpatients with COVID-19 confirmed by reverse transcription-polymerase chain reaction testing who received an ambulatory chest radiography between March 17, 2020 and October 24, 2020. In this study, full admission was defined as hospitalization within 14 days of the COVID-19 test for > 2 days with supplemental oxygen. Univariate analysis and machine learning algorithms were used to evaluate the relationship between the deep learning model predictions and hospitalization for > 2 days.ResultsThe study included 413 patients, 222 men (54%), with a median age of 51 years (interquartile range, 39–62 years). Fifty-one patients (12.3%) required full admission. A boosted decision tree model produced the best prediction. Variables included patient age, frontal chest radiograph predictions of morbid obesity, congestive heart failure and cardiac arrhythmias, and radiographic opacity, with an internally validated area under the curve (AUC) of 0.837 (95% CI: 0.791–0.883) on a test cohort.ConclusionDeep learning analysis of single frontal chest radiographs was used to generate combined comorbidity and pneumonia scores that predict the need for supplemental oxygen and hospitalization for > 2 days in patients with COVID-19 infection with an AUC of 0.837 (95% confidence interval: 0.791–0.883). Comorbidity scoring may prove useful in other clinical scenarios.

Steady State Experimental Characterization of a Twin Entry Turbine under Different Admission Conditions

The increasingly restrictive limits on exhaust emissions of automotive internal combustion engines imposed in recent years are pushing OEMs to seek new solutions to improve powertrain efficiency. Despite the increase in electric and hybrid powertrains, the turbocharging technique is still one of the most adopted solution in automotive internal combustion engines to achieve good efficiency with high specific power levels. Nowadays, turbocharged downsized engines are the most common solution to lower CO2 emissions. Pulse turbocharging is the most common boosting layout in automotive applications as the best response in terms of time-to-boost and exhaust energy extraction. In a high-fractionated engine with four or more cylinders, a twin entry turbine can be adopted to maximize pulse turbocharging benefits and avoid interaction in the discharge phase of the cylinders. The disadvantages of the twin entry turbine are mainly due to the complexity of the exhaust piping line and the high amount of information required to build a rigorous and reliable matching model. This paper presents a detailed experimental characterization of a twin entry turbine with particular reference to the turbine efficiency and the swallowing capacity under different admission conditions. The steady flow experimental campaign was performed at the turbocharger test bench of the University of Genoa, in order to analyze the behavior of the twin entry turbine in full, partial and unbalanced admission. These are the conditions in which the turbine must work instantaneously during its normal operation in engine application. The results show a different swallowing capacity of each sector and the interactions between the two entries.

Investigation of the Relative Performance of Vaned and Vaneless Mixed Flow Turbines for Medium and Heavy-Duty Diesel Engine Applications with Pulse Exhaust Systems

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;This paper details results of a numerical and experimental investigation into the relative performance of vaned and vaneless mixed flow turbines for application to medium and heavy-duty diesel engines utilizing pulse exhaust systems. Previous investigations into the impact of nozzle vanes on turbine performance considered only open turbine housings, whereas a majority of medium and heavy-duty diesel engine applications are six-cylinder engines using pulse exhaust systems with divided turbines. The two turbine stages for this investigation were carefully designed to meet the constraints of engines with pulse exhaust systems and to control confounding factors that would undermine the vaned vs vaneless performance comparison. Detailed CFD analysis and turbine dynamometer test results confirm a significant efficiency advantage for the vaned turbine stage under both full and partial admission conditions.&lt;/div&gt;&lt;/div&gt;

Using a CFD analysis of the flow capacity in a twin-entry turbine to develop a simplified physics-based model

The current paper presents a flow behaviour analysis of twin-entry radial turbines by means of experimental measurements and computational fluid dynamics (CFD) simulations. The experimental data were measured at partial, unequal and full admission conditions, and was used to globally validate CFD simulations. The experimental results hinted towards considering twin-entry turbines as two separated single-entry turbines working in parallel when used in simplified physics-based models such as in one-dimensional simulations. After analysing the CFD results, a simple flow capacity model was developed, exploiting some of the observed characteristic phenomena to reduce the number of fitting parameters to their minimum while keeping its accuracy and extrapolation capabilities.

Performance and Losses Analysis for Radial Turbine Featuring a Multi-Channel Casing Design

Abstract A novel control technique for radial turbines is under investigation for providing turbine performance controllability, especially in turbocharger applications. This technique is based on replacing the traditional spiral casing with a multi-channel casing (MC). The MC divides the turbine rotor inlet circumferentially into a certain number of channels. Opening and closing these channels controls the inlet area and, consequently, the turbine performance. The MC can be distinguished from other available control techniques in that it contains no movable parts or complicated control mechanisms. Within the casing, this difference makes it practical for a broader range of applications. In this investigation, a turbocharger featuring a turbine with MC has been tested on a hot gas test stand. The experimental test results show a reduction in the turbine operating efficiency when switching from full to partial admission. This reduction increases when reducing the admission percentage. To ensure the best performance of the turbine featuring MC while operating at different admission configurations, it becomes crucial to investigate its internal flow field at both full and partial admission to understand the reasons for this performance reduction. A full 3D computational fluid dynamics (CFD) model of the turbine was created for this investigation. It focuses on identifying the loss mechanisms associated with partial admission. Steady and unsteady simulations were performed and validated with available test data. The simulation results show that operating the turbine at partial admission results in highly disturbed flow. It also detects the places where aerodynamic losses occur and which are responsible for this performance reduction. This operation also shows flow unsteadiness even when operating at steady conditions. This unsteadiness depends mainly on the admission configuration and percentage.