CFD investigation of transonic axial compressor rotor blade at various off-design conditions

Flow separation over blade surfaces is an important parameter and its reduction or elimination can improve better aerodynamic performance, efficiency and stall margin. In this work, numerical investigation has been carried out to study the flow separation and performance analysis of a transonic axial compressor rotor blade at off-design operating conditions. The off-design cases studied comprised of compressor operation at 80%, 90%, 100% and 105% on the on-design rotational speed. The results are validated with experimental work from literature. Additionally, 3D flow visualisations and performance parameters were examined in detail to understand the blade to blade relative mach number distributions and shock front created by the model. Finally, the benefits of unsteady simulation on axial compressor blade performance predictions were examined

A review on the impact of aircraft cabin air quality and cabin pressure on human wellbeing

Airliner cabins present more complicated scenario due to different design and operation challenges owing to the extreme environmental conditions, complexity of the operational systems, and the authorities that govern such environments. The scientific evaluation is rendered difficult due to lack of empirical evidence determining the airliner cabin air quality as well as consequent health effects occurring due to short or long flight exposure. Crew members and passengers report dizziness, fatigue, headaches, sinus and ear problems, dry eyes and sore throats during and after travel. There are persistent concerns about the transmission of infectious agents such as influenza, tuberculosis and measles viruses during flights. Moreover, a systematic collection of data related to airplane environmental exposures is not yet available and the effects of environmental conditions on wellbeing of travelers and their comfort level are yet to be fully ascertained. In this work, a systematic review of the air quality inside the airliner cabin are discussed. The potential pollutants and their established causes are discussed. In addition to this, major health discomforts faced by the occupants are presented

Comparative evaluation of doxofylline and theophylline in patients of mild bronchial asthma

Background: Asthma is common chronic disease worldwide. Methylxanthines has been used in the treatment of asthma. The study was undertaken to compare two Methylxanthines theophylline and doxofylline at doses recommended and commonly used in clinical practice in Mild Bronchial Asthma Patients.Methods: Study was conducted in patients of Mild Bronchial Asthma in TB and chest disease department of a medical college hospital. It was randomized, prospective and open label. A total of 107 patients were divided in two group .Group I was administered 400 mg theophylline SR once daily and group II was administered doxofylline 400 mg twice a day orally. Spirometric variables symptom score, and adverse effects were recorded on day 0, 7 and 21 of therapy. Data were compared and analysed using SPSS version 16.Results: Results of the study showed that there was significant improvement in spirometric variables and clinical symptom score compared to pretreatment values after medication in both groups on 7th and 21st days of treatment. But there was no statistically significant difference between improvement in theophylline and doxofylline groups with respect to spirometric variables and symptom score. There was no significant difference in two groups with respect to side effects (p>0.05).Conclusions: It is concluded in Patients of mild Bronchial Asthma Theophylline and doxofylline improve the spirometric and clinical symptoms and doxofylline has no advantage over theophylline in terms of either efficacy or safety on the doses commonly used in current clinical practice

Review on Unconventional Wind Energy

Fossil fuel is the major source of energy and is a fast depleting resource. The phenomenal increase in fossil fuel consumption has adversely affected carbon footprint impacting our environment. With strict environmental regulations in place, the focus towards renewable sources of energy is gaining momentum supported by recent advancement in technologies in wind, hydro and solar. Wind turbines were the first forms of clean energy has seen a major increase in power production. The site restrictions, have limited the wind turbine from being used to its maximum potential. In recent years, the concept of some unconventional methods is being proposed. In this review, the various types of wind turbines are emphasized with their recent advances and depicting the challenges faced in various aspects. The reviews contain details mainly about 4 types of wind turbines i.e. floating offshore wind turbine, airborne wind turbine, highway wind turbine systems and locomotive mounted wind turbine

Preparing Delicate Cellulose Fabric by Utilizing Polyacrylamide Softener to Enhance Surface Smoothness and Quality Properties

Series dilutions of polyacrylamide softeners were made, applied at surfaces of cotton fabrics and cotton/polyester fabrics respectively. Surface adsorption of polyacrylamide based softeners enhanced all smoothness/softness properties of end substrate. Various formulations and concentration of acrylamide functional based softeners were studied by post treatment on cotton/polyester fabrics. Polyacrylamide functional softener fixation onto cotton/polyester fabrics was due to acrylamide groups, to improve reactivity with cellulose substrate thereby increasing cross linking and group formation by providing quality softness. The experimental data stipulate better substantives and networking of acrylamide functional group that can reveal formation of hydrophobic ?lm on surface of cotton fabrics and cotton/polyester fabrics. A tiny layer of applied polyacrylamide softeners also enhanced reduction of the surface roughness by increasing strength of polyacrylamide softener

A computational fluid dynamics study of combustion and emission performance in an annular combustor of a jet engine

This paper is a Computational Fluid Dynamics (CFD) study of the performance of a jet engine annular combustor that was subjected to various loading conditions. The aim is to comprehend the effect of various genuine working conditions on ignition and emission performance. The numerical models utilized for fuel ignition is the feasible k-ω model for turbulent stream, species transport (aviation fuel and air) with eddy-dissipation reaction modelling and pollution model for nitrogen oxides (NOX) emission. The results obtained confirm the findings described in the literature

Experimental and numerical study of stenotic flows

Atherosclerosis has been leading cause of deaths in several countries. Recent technical advances have allowed the investigation of stenotic flows and in understanding the implications with increased severity. Such studies shall provide detailed understanding of flow across stenosis and its progression. In the present study, a large artery representing segment of aorta is considered as test specimen. Experimental study is carried out by generating the pulsatile flow through pulsatile duplicator. Flow across normal and various severities of stenosis such as 25%, 50% and 75% are studied. Numerical simulation using CFD is also carried out in similar normal and stenosed models. A novel concept of using pulse duplicator to generate pulsatile waves and investigate the different stenosed models has been adopted. Results obtained experimentally and numerically are compared and agree well with that of clinical observations. This study demonstrates significant variation of haemodynamic in post-stenotic region with increased stenosis. Increased pulse pressure, phase lag is observed with increased severity. It is also observed that stenosis greater than 75% is significant as flow complexity is induced with considerable disturbance even in early and latter part of pulse cycle. Such study shall be useful in understanding the flow changes in stenosis and enhance clinical observation

Chitin based polyurethanes using hydroxyl terminated polybutadiene, part III: surface characteristics.

Hydroxy terminated polybutadiene (HTPB)-chitin based polyurethanes (PUs) with controlled hydrophobicity were synthesized using HTPB and toluene diisocyanate (TDI). The prepolymer was extended with different mass ratios of chitin and 1,4-butane diol (BDO). The effect of chitin contents in chain extender (CE) proportions on surface properties was studied and investigated. Incorporation of chitin contents into the final PU showed decrease in contact angle value of water drop, water absorption (%) and swelling behavior. The antibacterial activity of the prepared samples was affected by varying the chitin contents in the chemical composition of the final PU. The results demonstrated that the use of prepared material can be suggested as non-absorbable suture

Fluid-structure interaction in problems of patient specific transcatheter aortic valve implantation with and without paravalvular leakage complication

Paravalvular Leakage (PVL) has been recognized as one of the most dangerous complications in relation to Transcathether Aortic Valve Implantation (TAVI) activities. However, data available in the literature about Fluid Structure Interaction (FSI) for this specific problem are relatively limited. In the present study, the fluid and structure responses of the hemodynamics along the patient aorta model and the aortic wall deformation are studied with the aid of numerical simulation taking into account PVL and 100% TAVI valve opening. In particular, the aorta without valve (AWoV) is assumed as the normal condition, whereas an aorta with TAVI 26 mm for 100% Geometrical Orifice Area (GOA) is considered as the patient aorta with PVL complication. A 3D patient-specific aorta model is elaborated using the MIMICS software. Implantation of the identical TAVI valve of Edward SAPIEN XT 26 (Edwards Lifes ciences, Irvine, California) is considered. An undersized 26 mm TAVI valve with 100% valve opening is selected to mimic the presence of PVL at the aortic annulus. The present research indicates that the existence of PVL can increase the blood velocity, pressure drop and WSS in comparison to normal conditions, thereby paving the way to the development of recirculation flow, thrombus formation, aorta wall collapse, aortic rupture and damage of endothelium