scholarly journals Numerical investigation of the effects of fuselage upsweep in a propulsive fuselage concept

2021 ◽  
Author(s):  
Anaïs Luisa Habermann ◽  
Anubhav Gokhale ◽  
Mirko Hornung
Keyword(s):  
Negative Impact ◽  
Three Dimensional ◽  
Negative Effects ◽  
Commercial Aircraft ◽  
Cfd Simulations ◽  
Inlet Distortion ◽  
Propulsive Performance ◽  
Fuel Burn ◽  
Shaft Power ◽  
Axisymmetric Configuration

AbstractIn recent years, aircraft concepts employing wake-filling devices to reduce mission fuel burn have gained increasing attention. The study presented here aims at a detailed physical understanding of the effects of integrating a propulsive fuselage device on a commercial aircraft. Compared to an isolated, axisymmetric fuselage-propulsor configuration, a propulsive fuselage device experiences an increased circumferential inlet distortion due to three-dimensional geometric features of the aircraft. This study uses three-dimensional CFD simulations to investigate the effect of fuselage upsweep on the aero-propulsive performance of an aircraft configuration featuring a boundary layer ingestion device. It is shown that fuselage upsweep has a negative impact on the performance of a propulsive fuselage device as compared to an axisymmetric configuration. Increasing the upsweep angle by $$\Delta \alpha _{{{\text{SW}},{\text{PFC}}}} = 3.5^\circ$$ Δ α SW , PFC = 3 . 5 ∘ leads to an increase in required fuselage fan shaft power by 19%. Furthermore, it is demonstrated that the negative effects of fuselage upsweep on the propulsor’s performance can be effectively mitigated by a circumferential variation in the propulsor nacelle thickness.

Problems of Development of Small and Medium Russian Towns

2019 ◽  
pp. 24-29
Author(s):  
V V. Kafidov ◽  
V. N. Filippov ◽  
I. P. Filippova
Keyword(s):  
Urban Development ◽  
Urban Areas ◽  
Negative Impact ◽  
Physical Space ◽  
Living Environment ◽  
Transport Infrastructure ◽  
Negative Effects ◽  
Conceptual Approach ◽  
Fundamental Factor ◽  
New Buildings

The presented study addresses the problems of development of small and medium towns in Russia. Aim. The study aims to examine a town as a socio-economic environment where its residents exist and as the fundamental factor for the development of society.Tasks. The authors identify key problems in the development of small and medium Russian towns, which interferes with the historical appearance and has a negative impact on the living environment.Methods. Problems in the development of small and medium towns in Russia are examined using theoretical methods: systematic approach, statistical analysis, social and philosophical analysis.Results. The study identifies the main negative effects of the existing model of development of small and medium Russian towns, such as destruction of their historical and cultural appearance, distortion of the overall architectural motif, increased load on communications, and congestion of the transport infrastructure.Conclusions. At the current stage, efficient development of small and medium towns in Russia is impossible within the framework of the existing infill development. This chaotic process cannot be stopped without a new conceptual approach and changes in the legislative and normative framework of urban development. The only factor that determines the boundaries of the existing approach to urban development is the lack of physical space for new buildings in urban areas. The authors formulate proposals that would help to solve the problems of development of small and medium towns in Russia. 

Performance enhancement of Savonius wind turbine by blade shape and twisted angle modifications

2021 ◽  
pp. 095765092098794
Author(s):  
Ahmed M Nagib Elmekawy ◽  
Hassan A Hassan Saeed ◽  
Sadek Z Kassab
Keyword(s):  
Wind Turbine ◽  
Performance Enhancement ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Vertical Axis ◽  
Cfd Simulations ◽  
Sliding Mesh ◽  
Blade Shape ◽  
Rotor Shape ◽  
Twisting Angle

Three-dimensional CFD simulations are carried out to study the increase of power generated from Savonius vertical axis wind turbines by modifying the blade shape and blade angel of twist. Twisting angle of the classical blade are varied and several proposed novel blade shapes are introduced to enhance the performance of the wind turbine. CFD simulations have been performed using sliding mesh technique of ANSYS software. Four turbulence models; realizable k -[Formula: see text], standard k - [Formula: see text], SST transition and SST k -[Formula: see text] are utilized in the simulations. The blade twisting angle has been modified for the proposed dimensions and wind speed. The introduced novel blade increased the power generated compared to the classical shapes. The two proposed novel blades achieved better power coefficients. One of the proposed models achieved an increase of 31% and the other one achieved 32.2% when compared to the classical rotor shape. The optimum twist angel for the two proposed models achieved 5.66% and 5.69% when compared with zero angle of twist.

scholarly journals Radial Turbine Design for Solar Chimney Power Plants

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 674
Author(s):  
Paul Caicedo ◽  
David Wood ◽  
Craig Johansen
Keyword(s):  
Power Plants ◽  
Reference Frames ◽  
Three Dimensional ◽  
Discrete Ordinates ◽  
Large Area ◽  
Solar Chimney ◽  
Cfd Simulations ◽  
Radial Turbine ◽  
Design Changes ◽  
Turbine Design

Solar chimney power plants (SCPPs) collect air heated over a large area on the ground and exhaust it through a turbine or turbines located near the base of a tall chimney to produce renewable electricity. SCPP design in practice is likely to be specific to the site and of variable size, both of which require a purpose-built turbine. If SCPP turbines cannot be mass produced, unlike wind turbines, for example, they should be as cheap as possible to manufacture as their design changes. It is argued that a radial inflow turbine with blades made from metal sheets, or similar material, is likely to achieve this objective. This turbine type has not previously been considered for SCPPs. This article presents the design of a radial turbine to be placed hypothetically at the bottom of the Manzanares SCPP, the only large prototype to be built. Three-dimensional computational fluid dynamics (CFD) simulations were used to assess the turbine’s performance when installed in the SCPP. Multiple reference frames with the renormalization group k-ε turbulence model, and a discrete ordinates non-gray radiation model were used in the CFD simulations. Three radial turbines were designed and simulated. The largest power output was 77.7 kW at a shaft speed of 15 rpm for a solar radiation of 850 W/m2 which exceeds by more than 40 kW the original axial turbine used in Manzanares. Further, the efficiency of this turbine matches the highest efficiency of competing turbine designs in the literature.

scholarly journals Dependence of the Flue Gas Flow on the Setting of the Separation Baffle in the Flue Gas Tract

2021 ◽  
Vol 11 (7) ◽  
pp. 2961
Author(s):  
Nikola Čajová Kantová ◽  
Alexander Čaja ◽  
Marek Patsch ◽  
Michal Holubčík ◽  
Peter Ďurčanský
Keyword(s):  
Particulate Matter ◽  
Flue Gas ◽  
Gas Flow ◽  
Negative Impact ◽  
Combustion Process ◽  
Cfd Simulations ◽  
Piv Measurements ◽  
Computational Fluid Dynamics Cfd ◽  
Particle Imaging ◽  
Combustion Of Solid Fuels

With the combustion of solid fuels, emissions such as particulate matter are also formed, which have a negative impact on human health. Reducing their amount in the air can be achieved by optimizing the combustion process as well as the flue gas flow. This article aims to optimize the flue gas tract using separation baffles. This design can make it possible to capture particulate matter by using three baffles and prevent it from escaping into the air in the flue gas. The geometric parameters of the first baffle were changed twice more. The dependence of the flue gas flow on the baffles was first observed by computational fluid dynamics (CFD) simulations and subsequently verified by the particle imaging velocimetry (PIV) method. Based on the CFD results, the most effective is setting 1 with the same boundary conditions as those during experimental PIV measurements. Setting 2 can capture 1.8% less particles and setting 3 can capture 0.6% less particles than setting 1. Based on the stoichiometric calculations, it would be possible to capture up to 62.3% of the particles in setting 1. The velocities comparison obtained from CFD and PIV confirmed the supposed character of the turbulent flow with vortexes appearing in the flue gas tract, despite some inaccuracies.

scholarly journals In the Same Boat, but not Equals: The Heterogeneous Effects of Indirect Taxation on Child Health in Punjab-Pakistan

2020 ◽  
Vol 11 (3) ◽  
Author(s):  
Faiz Ur Rehman ◽  
Muhammad Nasir
Keyword(s):  
Negative Impact ◽  
Income Group ◽  
Z Score ◽  
Negative Effects ◽  
Indirect Taxation ◽  
Nutrition Survey ◽  
Lower Income Group ◽  
Food Items ◽  
Heterogeneous Effects ◽  
The Impact

AbstractThe 2011 National Nutrition Survey of Pakistan revealed that 51% of the country’s population was consuming less than 2,100 calories a day. In the backdrop of rising food insecurity, hunger, and malnutrition in Pakistan, this study aims to measure the effects of indirect taxation on health outcomes of children (<5 years). More specifically, the impact of the incidence of General Sales Tax (GST) in the province of Punjab has been estimated on a child’s height and weight. The proponents of the uniform GST argue that the tax would not affect children because most food items consumed by children are exempted from the GST. However, the opponents believe that households, especially those belonging to the lower-income group, would reallocate resources away from children in the face of higher GST. To study these effects, we utilized three different waves (2007–08, 2011 & 2014) of Multiple Indicators Cluster Surveys (MICS). The results show that the tax incidence, and not the GST rate, has a significantly negative impact on children’s height-for-age Z-score (HAZ). No effect was found on the weight-for-age-z-score (WAZ). These results are robust to different specifications and exhibit considerable heterogeneity across different income groups. These findings suggest that the exemption of certain food items for children from the GST may not eliminate the negative effects of this tax on a child’s health. Thus, our study raises concerns about the long term welfare consequences of GST.

scholarly journals Transvaginal Hybrid-NOTES procedures—do they have a negative impact on pregnancy and delivery?

2021 ◽  
Author(s):  
Panagiotis Thomaidis ◽  
Niklas J. Weltermann ◽  
Claudia S. Seefeldt ◽  
Dana C. Richards ◽  
Axel Sauerwald ◽  
...  
Keyword(s):  
Negative Impact ◽  
Male Partner ◽  
Current Data ◽  
Reproductive Age ◽  
Negative Effects ◽  
Desire For Children ◽  
Pregnancy And Delivery ◽  
Hybrid Notes ◽  
Type Of Delivery

Abstract Purpose We conducted a retrospective observational study in order to identify negative effects of NOTES procedures (Natural Orifice Transluminal Endoscopic Surgery) with transvaginal specimen removal on pregnancy and delivery. Methods From the total population of 299 patients in our NOTES registry, we tried to contact the 121 patients who were of reproductive age (≤ 45 years) at the time of a transvaginal NOTES procedure. They were interviewed by telephone regarding their desire for children, post NOTES-operation pregnancies, and type of delivery using a structured questionnaire. The collected data was analyzed and compared with current data. Results We were able to contact 76 patients (follow-up rate: 62.8%) with a median follow-up of 77 months after surgery (33–129 months). Twenty of 74 participating patients had a desire for children (27.0%). One of them and another's male partner were diagnosed as infertile. Regarding the remaining 18 patients, 14 became pregnant, and three of them became pregnant twice. Considering these 17 pregnancies, there was one miscarriage (5.9%) and one twin birth (5.9%). On average, childbirth occurred 44 months after the NOTES procedure. With regard to the type of delivery, 10 vaginal births (58.8%) and 7 caesarean sections (41.2%) occurred. Thus, the rate of fulfilled desire for children was 77.8%. Compared with the literature, no difference to the normal course could be detected. Conclusion There is no sign that the transvaginal approach in Hybrid-NOTES, with removal of the specimen through the vagina, has a negative effect on conception, the course during pregnancy, or the type of delivery.

scholarly journals Characteristics of Newly Developed Extruded Products Supplemented with Plants in a Form of Microwave-Expanded Snacks

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2791
Author(s):  
Katarzyna Lisiecka ◽  
Agnieszka Wójtowicz ◽  
Marek Gancarz
Keyword(s):  
Physical Properties ◽  
Nutritional Value ◽  
Negative Impact ◽  
Total Phenolic ◽  
Extrusion Cooking ◽  
Negative Effects ◽  
Plant Materials ◽  
Texture Profile ◽  
Fresh Plant Material ◽  
Extruded Products

The following research focuses on the possibility of applying fresh plant material as a carrot pulp to supplement newly developed extruded products in the form of pellets and microwave-expanded snacks. Fresh carrot pulp, as a valuable vegetable ingredient, was used in the amount of 2.5 g/100 g to 30.0 g/100 g in a potato-based recipe. The snack pellets were processed via extrusion-cooking, using a single-screw extruder with a plasticizing unit L/D = 18, and the use of variable screw speeds. The produced pellets underwent microwave expansion to limit the fat content, so as to produce ready-to-eat (RTE) snacks. The pellets and snacks were tested for nutritional value, as well as for selected quality features: physical properties, structure, pasting characteristics, and texture profile, and PCA analysis and a correlation matrix were performed on the obtained results. Microwave expansion of pellets increased the total phenolic content, the antioxidant activity, water absorption index and lightness of snacks, but decreased the bulk density and setback values of the expanded products when compared to pellets. Generally, we found that it was possible to use up to 30.0 g/100 g of fresh carrot pulp with a positive effect on nutritional value, and without negative effects on the physical properties of extruded products. Both the extrusion-cooking and microwave expansion can minimize the negative impact on plant materials, due to the short processing time.

Unsteady Three-Dimensional Analysis of Inlet Distortion in a Transonic Fan

2006 ◽  
Author(s):  
Peng Sun ◽  
Guotal Feng
Keyword(s):  
Shock Wave ◽  
Total Pressure ◽  
Large Scale ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Inlet Distortion ◽  
Flow Loss ◽  
Large Scale Vortex ◽  
Total Temperature ◽  
Transonic Fan

A time-accurate three-dimensional Navier-Stokes solver of the unsteady flow field in a transonic fan was carried out using "Fluent-parallel" in a parallel supercomputer. The numerical simulation focused on a transonic fan with inlet square wave total pressure distortion and the analysis of result consisted of three aspects. The first was about inlet parameters redistribution and outlet total temperature distortion induced by inlet total pressure distortion. The pattern and causation of flow loss caused by pressure distortion in rotor were analyzed secondly. It was found that the influence of distortion was different at different radial positions. In hub area, transportation-loss and mixing-loss were the main loss patterns. Distortion not only complicated them but enhanced them. Especially in stator, inlet total pressure distortion induced large-scale vortex, which produced backflow and increased the loss. While in casing area, distortion changed the format of shock wave and increased the shock loss. Finally, the format of shock wave and the hysteresis of rotor to distortion were analyzed in detail.

Effects of Inlet Distortion on the Flow Field in a Transonic Compressor Rotor

1996 ◽  
Author(s):  
Chunill Hah ◽  
Douglas C. Rabe ◽  
Thomas J. Sullivan ◽  
Aspi R. Wadia
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Viscous Flow ◽  
Total Pressure ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Aerodynamic Loss ◽  
Transonic Compressor ◽  
Inlet Distortion ◽  
Compressor Rotor

The effects of circumferential distortions in inlet total pressure on the flow field in a low-aspect-ratio, high-speed, high-pressure-ratio, transonic compressor rotor are investigated in this paper. The flow field was studied experimentally and numerically with and without inlet total pressure distortion. Total pressure distortion was created by screens mounted upstream from the rotor inlet. Circumferential distortions of 8 periods per revolution were investigated at two different rotor speeds. The unsteady blade surface pressures were measured with miniature pressure transducers mounted in the blade. The flow fields with and without inlet total pressure distortion were analyzed numerically by solving steady and unsteady forms of the Reynolds-averaged Navier-Stokes equations. Steady three-dimensional viscous flow calculations were performed for the flow without inlet distortion while unsteady three-dimensional viscous flow calculations were used for the flow with inlet distortion. For the time-accurate calculation, circumferential and radial variations of the inlet total pressure were used as a time-dependent inflow boundary condition. A second-order implicit scheme was used for the time integration. The experimental measurements and the numerical analysis are highly complementary for this study because of the extreme complexity of the flow field. The current investigation shows that inlet flow distortions travel through the rotor blade passage and are convected into the following stator. At a high rotor speed where the flow is transonic, the passage shock was found to oscillate by as much as 20% of the blade chord, and very strong interactions between the unsteady passage shock and the blade boundary layer were observed. This interaction increases the effective blockage of the passage, resulting in an increased aerodynamic loss and a reduced stall margin. The strong interaction between the passage shock and the blade boundary layer increases the peak aerodynamic loss by about one percent.

Sign in / Sign up

Export Citation Format

Share Document