A Comparison of Two Fan Stage Designs With Different Rotor Leading Edge Sweep

2014 ◽  
Author(s):  
John Gunaraj ◽  
David Hanson ◽  
Jeffrey Hayes ◽  
Heath Lorzel ◽  
Nick Nolcheff ◽  
...  
Keyword(s):  
Pressure Ratio ◽  
Stability Margin ◽  
Leading Edge ◽  
Flow Capacity ◽  
Numerical Predictions ◽  
Performance Trends ◽  
Ansys Cfx ◽  
Significant Difference ◽  
Total Temperature ◽  
The Individual

Two modern single-stage fans have been designed to meet the same set of performance objectives. The most significant difference between the two designs is the fan rotor leading edge sweep. The baseline rotor has a moderately aft swept leading edge while the redesigned rotor has a more complex sweep distribution, including moderate forward sweep in the tip region. Each stage consists of the fan rotor, full span stator, and split mid-frame, and is designed for a medium bypass ratio turbofan application. The stator and the mid-frame are identical for the two configurations. The primary purpose of this study is to validate the CFD methodology, in this case a steady ANSYS-CFX approach, to predict the fan stage performance at the operating point at two tested speeds and also to predict the stalling throttle condition. Numerical predictions and engine test results are presented and show good agreement. These predicted results are compared with high quality test data including thorough measurements of total pressure and total temperature at both the rotor and stator exits allowing for a detailed understanding and comparison of the individual blade row performance. The analytical model identifies the key performance trends, including an increase in flow capacity and stability margin with equivalent stage pressure ratio and efficiency for the redesigned fan relative to the baseline.

Aerodynamic and Aeroacoustic Optimization of a Transonic Centrifugal Compressor

2014 ◽  
Author(s):  
Peng Wang ◽  
Mehrdad Zangeneh
Keyword(s):  
Pressure Ratio ◽  
Transonic Compressor ◽  
Numerical Predictions ◽  
Ansys Cfx ◽  
Transonic Centrifugal Compressor ◽  
Blade Tip ◽  
Surface Scheme ◽  
Lower Noise ◽  
Integral Surface ◽  
Good Agreement

The performance of transonic compressors can be characterized aerodynamically and aeroacoustically. In this paper, the DLR SRV2 compressor without vaned diffusers and its redesigned version are studied. The redesign strategy (Zangeneh et al. 2011 [1]) utilized the 3D inverse design and CFD analysis. Both compressors were analyzed in ANSYS CFX 11, and the computational results show that the predicted pressure-ratio and efficiency of the original compressor have good agreement with experimental results. The simulations have also revealed that the redesigned one is superior at both design and off-design points at different rotating speeds. This work applies a convective FW-H method to further investigate the noise radiation from these two compressors. As the blade tip speed is supersonic, the permeable integral surface scheme must be adopted. The flow quantities needed as the inputs to the FW-H solver were extracted from the CFD solutions. The numerical predictions of the noise SPLs at blade passing frequency and its harmonics match the experimental measurements reasonably well. It is found that the original compressor has significant variations of SPLs as the operating mass flow rate changes whereas the redesigned one has much slighter variations. At peak efficiency the redesigned compressor has a lower noise level. This study provides insights for the optimal design of a transonic compressor when good aerodynamic and aeroacoustic performance are both required.

scholarly journals The influence of flow passage geometry on the performances of a supercritical CO2 centrifugal compressor

2018 ◽  
Vol 22 (Suppl. 2) ◽  
pp. 409-418 ◽  
Author(s):  
Dong-Bo Shi ◽  
Yu-Qi Wang ◽  
Yong-Hui Xie ◽  
Di Zhang
Keyword(s):  
Centrifugal Compressor ◽  
Supercritical Co2 ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Thermal Design ◽  
Original Design ◽  
Impeller Blade ◽  
Flow Passage ◽  
Ansys Cfx ◽  
Design Idea

In this paper, based on the thermodynamic design of the supercritical carbon dioxide (sCO2) centrifugal compressor, the design idea of the flow passage geometries and the method to improve the performance of the sCO2 centrifugal compressor are discussed. With the help of commercial software ANSYS CFX, the influence of the shape of the leading edge and trailing edge is studied, and the elliptical leading edge makes the pressure ratio 10.30% higher and the efficiency 3.95% higher than the square leading edge. By changing the forward-swept angle and backward-swept angle of the leading edge, the effects of aerodynamic swept shape in sCO2 centrifugal compressor are discussed. The effect of the gap between the impeller blade and diffuser blade is discussed, and the 10 mm gap makes the performance best. The pressure ratio is increased by 2.5% compared with the original design, while at the same time the efficiency is slightly improved. In summary, based on thermal design of the sCO2 centrifugal compressor, the effects of different flow geometries are analyzed in detail.

Research on the Matching Relationship Between HPT and LPT of One and One-Half Vaneless Contra-Rotating Turbines

2016 ◽  
Author(s):  
Xiao Xu ◽  
Qingjun Zhao ◽  
Weiwei Luo ◽  
Fei Tang ◽  
Xiaolei Sun
Keyword(s):  
High Performance ◽  
High Efficiency ◽  
Pressure Ratio ◽  
Weight Ratio ◽  
Numerical Work ◽  
Matching Conditions ◽  
Flow Capacity ◽  
Significant Difference ◽  
Stage 1 ◽  
Two Stages

The vaneless contra-rotating turbine (VCRT) has the potential to improve the thrust-to-weight ratio for future high performance propulsion systems. Without the inter-stage vane, the variation of the high pressure turbine (HPT) exit swirl, under off-design conditions, can introduce more significant effects on the operation of the low pressure turbine (LPT). This study performed both analytical and numerical work investigating the matching relationship between the two stages of one and one-half stage (1+1/2) VCRTs. The significant difference of 1+1/2 VCRTs from conventional turbines, under choking geometry-fixed conditions, was found the flow capacity at the station between HPT and LPT is not invariant. The matching relationship between HPT and LPT is indeed how the flow capacity at the station between the two stages varies for different matching conditions. Influenced by the variation of the flow capacity, both the total pressure ratio of HPT and the corrected mass flow rate at the inlet of LPT are confined by the matching relationship. The corrected rotational speeds of the two stages define different matching conditions. A correlation, defining the matching conditions that LPT can work with constant incidence, was also derived. With aid of the correlation, the matching conditions can be controlled assuring LPT work with stable high efficiency. In the end, an application of incorporating the matching relationship into the investigation of engine performances is demonstrated, in which, a turbojet performance cycle analysis was performed. This paper has established a framework guiding how to obtain the matching relationship between the two stages of 1+1/2 VCRTs and incorporate it into the investigation of engine performances.

Turbomachinery Active Subspace Performance Maps

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Pranay Seshadri ◽  
Shahrokh Shahpar ◽  
Paul Constantine ◽  
Geoffrey Parks ◽  
Mike Adams
Keyword(s):  
Performance Metrics ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Flow Capacity ◽  
Trade Offs ◽  
Design Variables ◽  
Contour Plots ◽  
Active Subspaces ◽  
The Impact ◽  
Active Subspace

Turbomachinery active subspace performance maps are two-dimensional (2D) contour plots that illustrate the variation of key flow performance metrics with different blade designs. While such maps are easy to construct for design parameterizations with two variables, in this paper, maps will be generated for a fan blade with twenty-five design variables. Turbomachinery active subspace performance maps combine active subspaces—a new set of ideas for dimension reduction—with fundamental turbomachinery aerodynamics and design spaces. In this paper, contours of (i) cruise efficiency, (ii) cruise pressure ratio (PR), (iii) maximum climb flow capacity, and (iv) sensitivity to manufacturing variations are plotted as objectives for the fan. These maps are then used to infer pedigree design rules: how best to increase fan efficiency; how best to desensitize blade aerodynamics to the impact of manufacturing variations? In the present study, the former required both a reduction in PR and flow capacity—leading to a reduction of the strength of the leading edge bow wave—while the latter required strictly a reduction in flow capacity. While such pedigree rules can be obtained from first principles, in this paper, these rules are derived from the active subspaces. This facilitates a more detailed quantification of the aerodynamic trade-offs. Thus, instead of simply stating that a particular design is more sensitive to manufacturing variations; or that it lies on a hypothetical “efficiency cliff,” this paper seeks to visualize, quantify, and make precise such notions of turbomachinery design.

Turbomachinery Active Subspace Performance Maps

2017 ◽  
Author(s):  
Pranay Seshadri ◽  
Shahrokh Shahpar ◽  
Paul Constantine ◽  
Geoffrey Parks ◽  
Mike Adams
Keyword(s):  
Performance Metrics ◽  
Pressure Ratio ◽  
Leading Edge ◽  
Flow Capacity ◽  
Trade Offs ◽  
Design Variables ◽  
Contour Plots ◽  
Active Subspaces ◽  
The Impact ◽  
Active Subspace

Turbomachinery active subspace performance maps are 2D contour plots that illustrate the variation of key flow performance metrics with different blade designs. While such maps are easy to construct for design parameterizations with two variables, in this paper maps will be generated for a fan blade with twenty-five design variables. Turbomachinery active subspace performance maps combine active subspaces — a new set of ideas for dimension reduction — with fundamental turbomachinery aerodynamics and design spaces. In this paper, contours of (i) cruise efficiency, (ii) cruise pressure ratio, (iii) maximum climb flow capacity and (iv) sensitivity to manufacturing variations, are plotted as objectives for the fan. These maps are then used to infer pedigree design rules: how best to increase fan efficiency; how best to desensitize blade aerodynamics to the impact of manufacturing variations? In the present study, the former required both a reduction in pressure ratio and flow capacity — leading to a reduction of the strength of the leading edge bow wave — while the latter required strictly a reduction in flow capacity. While such pedigree rules can be obtained from first principles, in this paper these rules are derived from the active subspaces. This facilitates a more detailed quantification of the aerodynamic trade-offs. Thus, instead of simply stating that a particular design is more sensitive to manufacturing variations; or that it lies on a hypothetical ‘efficiency cliff’, this paper seeks to visualize, quantify and make precise such notions of turbomachinery design.

Writing in Aphasia Rehabilitation: Cursive vs Manuscript

1976 ◽  
Vol 41 (4) ◽  
pp. 523-529 ◽  
Author(s):  
Daniel R. Boone ◽  
Harold M. Friedman
Keyword(s):  
Correct Response ◽  
The Other ◽  
Read Aloud ◽  
Writing Style ◽  
Reading And Writing ◽  
Manual Responses ◽  
Significant Difference ◽  
Written Form ◽  
The Individual ◽  
Read Number

Reading and writing performance was observed in 30 adult aphasic patients to determine whether there was a significant difference when stimuli and manual responses were varied in the written form: cursive versus manuscript. Patients were asked to read aloud 10 words written cursively and 10 words written in manuscript form. They were then asked to write on dictation 10 word responses using cursive writing and 10 words using manuscript writing. Number of words correctly read, number of words correctly written, and number of letters correctly written in the proper sequence were tallied for both cursive and manuscript writing tasks for each patient. Results indicated no significant difference in correct response between cursive and manuscript writing style for these aphasic patients as a group; however, it was noted that individual patients varied widely in their success using one writing form over the other. It appeared that since neither writing form showed better facilitation of performance, the writing style used should be determined according to the individual patient’s own preference and best performance.

Aftermath Effect Of GST On Consumer Purchasing Power

2019 ◽  
Vol 118 (5) ◽  
pp. 122-131
Author(s):  
S. Thowseaf ◽  
M. Ayisha Millath ◽  
K. Malik Ali
Keyword(s):  
Living Standard ◽  
Purchasing Power ◽  
Percentage Increase ◽  
Defense System ◽  
Key Factors ◽  
Predominant Role ◽  
Tax System ◽  
Significant Difference ◽  
The Individual ◽  
Taxation System

Tax is an important source of income for the country. It is through tax; country strengthens its defense system, infrastructure, and government. Hence, tax system plays a predominant role in developing country’s economy. The complication in taxation system and liberty for taxpayers are key factors generating loopholes for corruption. GST is superior taxation system over VAT but, if neither properly implemented nor scrutinized according to the economy, it is people residing get affected.  GST taxation system is capable of increasing legal transaction, reducing corruption and complexity that exists in current taxation. India is 166th country to adopt GST and GST taxation slab in India is 0%, 5%, 12%, 18% and 28%.  Although average Tax levied is 14.8750% in India, it is 28% tax that is levied for most of the commodities, which are directly or indirectly used in everyday life of common individuals. Despite, GST being favorable to distributor in-terms of profit and government to attain tax by increasing legal transaction through invoice. It is noted that for the same percentage of taxation, the amount does not vary for VAT and GST. The tax slab decreased for 71 commodities and no change in 21 commodities; there has been an increase in tax slab for 60 commodities. 26% taxation was levied for most commodities considered was currently levied by 28% taxation which is greater than before. It was found that average tax percentage reduced was calculated to be 6.07143. The average tax percentage increase was calculated to be 4.7833 percentage for the considered commodities. The overall tax average tax percentage is estimated to be 14.8750% which does not have a significant difference concerning tax levied before GST, which was calculated to be 15.7829% for considered commodities. Therefore, the consumer purchasing power and overall living standard of the individual in India will remain almost same.

scholarly journals A comparison between Asians and Caucasians in the dimensions of the femoral isthmus based on a 3D-CT analysis of 1189 adult femurs

2021 ◽  
Author(s):  
Darius M. Thiesen ◽  
Dimitris Ntalos ◽  
Alexander Korthaus ◽  
Andreas Petersik ◽  
Karl-Heinz Frosch ◽  
...  
Keyword(s):  
Proximal Femur ◽  
Strong Predictor ◽  
Matched Pair ◽  
3D Ct ◽  
Femur Fractures ◽  
Matched Pair Analysis ◽  
Significant Difference ◽  
Ct Analysis ◽  
Ct Data ◽  
The Individual

Abstract Introduction For successful intramedullary implant placement at the femur, such as nailing in unstable proximal femur fractures, the use of an implant that at least reaches or exceeds the femoral isthmus and yields sufficient thickness is recommended. A number of complications after intramedullary femoral nailing have been reported, particularly in Asians. To understand the anatomical features of the proximal femur and their ethnic differences, we aimed to accurately calculate the femoral isthmus dimensions and proximal distance of Asians and Caucasians. Methods In total, 1189 Asian and Caucasian segmented 3D CT data sets of femurs were analyzed. The individual femoral isthmus diameter was precisely computed to investigate whether gender, femur length, age, ethnicity or body mass index have an influence on isthmus diameters. Results The mean isthmus diameter of all femurs was 10.71 ± 2.2 mm. A significantly larger diameter was found in Asians when compared to Caucasians (p < 0.001). Age was a strong predictor of the isthmus diameter variability in females (p < 0.001, adjusted r2 = 0.299). With every year of life, the isthmus showed a widening of 0.08 mm in women. A Matched Pair Analysis of 150 female femurs showed a significant difference between isthmus diameter in Asian and Caucasian femurs (p = 0.05). In 50% of the cases the isthmus was found in a range of 2.4 cm between 16.9 and 19.3 cm distal to the tip of the greater trochanter. The female Asian femur differs from Caucasians as it is wider at the isthmus. Conclusions In absolute values, the proximal isthmus distance did not show much variation but is more proximal in Asians. The detailed data presented may be helpful in the development of future implant designs. The length and thickness of future standard implants may be considered based on the findings.

A Comparison of Colectomy Outcomes Utilizing Open, Laparoscopic, and Robotic Techniques

2020 ◽  
pp. 000313482097338
Author(s):  
Elizabeth McCarthy ◽  
Benjamin L. Gough ◽  
Michael S. Johns ◽  
Alexandra Hanlon ◽  
Sachin Vaid ◽  
...  
Keyword(s):  
Postoperative Recovery ◽  
Logistic Regression Models ◽  
Community Institution ◽  
Physical Status Classification ◽  
Estimated Blood Loss ◽  
Comparative Review ◽  
Significant Difference ◽  
American Society ◽  
The Individual ◽  
American Society Of Anesthesiologists

Introduction Robotic colectomy could reduce morbidity and postoperative recovery over laparoscopic and open procedures. This comparative review evaluates colectomy outcomes based on surgical approach at a single community institution. Methods A retrospective review of all patients who underwent colectomy by a fellowship-trained colon and rectal surgeon at a single institution from 2015 through 2019 was performed, and a cohort developed for each approach (open, laparoscopic, and robotic). 30-day outcomes were evaluated. For dichotomous outcomes, univariate logistic regression models were used to quantify the individual effect of each predictor of interest on the odds of each outcome. Continuous outcomes received a similar approach; however, linear and Poisson regression modeling were used, as appropriate. Results 115 patients were evaluated: 14% (n = 16) open, 44% (n = 51) laparoscopic, and 42% (n = 48) robotic. Among the cohorts, there was no statistically significant difference in operative time, rate of reoperation, readmission, or major complications. Robotic colectomies resulted in the shortest length of stay (LOS) (Kruskal-Wallis P < .0001) and decreased estimated blood loss (EBL) (Kruskal-Wallis P = .0012). Median age was 63 years (interquartile range [IQR] 53-72). 54% (n = 62) were female. Median American Society of Anesthesiologists physical status classification was 3 (IQR 2-3). Median body mass index was 28.67 (IQR 25.03-33.47). A malignant diagnosis was noted on final pathology in 44% (n = 51). Conclusion Among the 3 approaches, there was no statistically significant difference in 30-day morbidity or mortality. There was a statistically significant decreased LOS and EBL for robotic colectomies.

Safety climate and related factors in rehabilitation nurses of hospitals in Iran

Work ◽  
2021 ◽  
pp. 1-8
Author(s):  
Javad vatani ◽  
Zahra Khanikosarkhizi ◽  
Mohammad Ali Shahabi Rabori ◽  
mohammad khandan ◽  
Mohsen aminizadeh ◽  
...  
Keyword(s):  
Safety Climate ◽  
Cross Sectional Study ◽  
P Value ◽  
Related Factors ◽  
Cross Sectional ◽  
Climate Assessment ◽  
Safety Work ◽  
Significant Difference ◽  
Training Courses ◽  
The Individual

BACKGROUND: Safety climate is a common insight of staff that indicates individuals’ attitudes toward safety and priority of safety at work. OBJECTIVES: Nursing is a risky job where paying attention to safety is crucial. The assessment of the safety climate is one of the methods to measure the safety conditions in this occupation. The aim of this study was to assess the safety climate of rehabilitation nurses working in hospitals in Tehran. METHODS: This is a cross-sectional study which was carried out on 140 rehabilitation nurses selected from all hospitals and clinics in Tehran in 2019. To collect the required data, a two-section questionnaire was used. The first section was related to demographic factors and the second part (22 statements) was to measure the safety climate using nurses’ safety climate assessment questionnaire. The collected data were analyzed by SPSS V16 using independent t-test, ANOVA, Kruskal-Wallis and Mann-Whitney U test at the 5% level. RESULTS: Findings showed that the total mean of safety climate was 3.06±0.56. According to the results, a significant difference was found between the positive and negative satisfaction of nurses with safety climates (P-value = 0.03), communication with nurses (P-value = 0.01) and supervisors’ attitude (P-value = 0.02). Furthermore, a significant difference in safety climate between the individual with the second job and the individual without second could be observed (P-value = 0.01). CONCLUSIONS: The results indicated that the safety climate was not at an acceptable level. Thus, it is essential to introduce safety training courses (e.g. safety, work-rest balance, and so on) and to improve the safety performance at work.

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