131 research outputs found
Aerodynamic design for a pusher propeller spinner
No full textThe present work has placed particular importance on the spinner aerodynamic design in order to enhance the performance of a pusher propeller configuration. The research has been focused on the aerodynamic shaping of the spinner in order to provide a better understanding of the nacelle-blade-spinner interaction in cruise conditions. The set of experiments were carried out by performing a series of steady-state Reynolds-averaged Navier-Stokes (RANS) CFD simulations with k-omega STT as turbulence model. Generally speaking, the pressure drag reduction was related to large values of Cp nearby the spinner wall; however, the pressure drag of shorter spinners depended mostly on the formation of the hub vortex, while the pressure drag improvement on the longer spinner designs depended on the pressure recovery at the spinner. A tangent spinner design was introduced to reduce the peaks of the pressure distribution observed at the nacelle-spinner transition, at the same time that moved the expansion section of the spinner downstream ahead the blade root thus improving the pressure recovery. The tangent cases induced an average increment in the nacelle drag of 5.77% compared to the original value, while the torque was reduced by only 0.05%. The spinner drag was reduced by 47.82% on average and the relative propeller efficiency was improved at a maximum value of 0.88%. The tangent spinner design was tested with passive boundary layer control tools such as small baffles located close to the blade root trailing edge. The relative propeller efficiency was improved at a maximum of 1.89% and the spinner drag reduced 122.3% turning the spinner drag into a thrust component. The direction of the flow was significantly more aligned with the rotational axis (From a stationary perspective) which increased the spinner pressure recovery. The detrimental effects of the Hub vortex at the end of the spinner were completely mitigated.Aerospace Engineerin
Experimental investigation of the influence of spinner shape on fan performance in subsonic uniform and non-uniform flow
No full textThe aerospace industry is always trying to improve aircraft designs in an attempt to improve its performance and also make it clean and sustainable. Boundary layer Ingestion (BLI) is one of the concepts which has the potential to improve fuel and overall propulsive efficiency of an aircraft. The BLI configuration have the engines integrated with the fuselage. The previous research and studies done so far have shown that the inlet distortion, from the ingested boundary layer and the consequent flow non-uniformity has detrimental effects on the aerodynamic performance of the fans and compressors in an engine. This novel concept of BLI has a lot of potential to not only improve the overall propulsive efficiency of an aircraft engine, but also to address the sustainability goals that the aviation industry has, with regards to emissions and noise pollution. For this technology to be viable, the engine fans need to be able to operate reliably and efficiently in continuous distorted inflow conditions.The present thesis is an experimental investigation on how the spinner shape influences the performance of the fan operating with distorted inflow. The main objective is to understand how the flow field behaves and in turn affect the stability and performance of the fan in subsonic uniform and non-uniform flow conditions with different spinner shapes. Performance maps and noise data are obtained at different flow speeds and Particle Image Velocimetry (PIV) measurements are taken to understand how the flow behaves downstream and upstream of the fan. This helped in understanding the effects of the fan interactions with the flow, which in turn was used to understand and explain the influence of the spinner shape on fan performance. Not much research has been done on the influence of spinner shapes and very few have studied PIV downstream of the fan. So this thesis yields valuable results that will contribute to the research done by the scientific community in this field.Aerospace Engineerin
IODP Expedition 361 Magnetic remanence (spinner)
No full textMagnetic remanence was measured on discrete samples by an Agico JR-6A spinner magnetometer, first as natural remanent magnetization (NRM) and then after demagnetization or remagnetization steps were performed on the samples (e.g., alternating field [AF] demagnetization, thermal demagnetization [TD], or isothermal remanent magnetization [IRM])
Stem cell expansion and bioreactor development
No full textPhDA major challenge to the clinical success of cell-based tissue engineering strategies is the ability to obtain sufficient numbers of cells within an acceptable time frame. The expansion of cells on microcarriers within spinner flask bioreactor has shown promise in meeting that challenge. Spinner flask microcarrier technology is space-saving and media utilisation efficient. However, further optimisation in terms of, for example, seeding efficiency, expansion rates and harvest efficiency is necessary to realise the clinical potential of this technology. The present work is designed to improve cell expansion rates. It involves investigation of microcarrier composition and surface structure and spinner flask shear stress on cell growth.
BMSC growth on PHBV microcarriers was superior to PCL and PLGA microcarriers and comparable to Cytodex 1 microcarriers. Lower density PHBV microcarriers showed promise as a superior alternative to Cytodex 1. Two different impeller designs employed in the w/o/w method of microcarrier synthesis resulted in smoother and rougher PCL microcarriers with Ra = 1.77 ± 0.42 μm to 6.4 ± 1.48 μm respectively. Superior BMSC growth was observed on the rougher PCL microcarriers. Differentiation potential along the osteogenic and adipogenic lineages of BMSCs expanded on the microcarrier types was retained.
Particle Image Velocimetry was used to quantify shear stress within a spinner flask bioreactor. It was found that 80% of the shear stress was localised within the impeller region which occupied 55% of the bioreactor working volume. Shear stress increased as Cytodex 1 microcarrier concentration and impeller rotational speed increased. Superior BMSC growth rates on microcarriers were observed for the lowest shear stress experimental group (3.4 x 10-3 N/m2 ≤ impeller region mean shear stress ≤ 4.6 x 10-3 N/m2) as compared to the three higher shear stress groups (5.5 x 10-3 N/m2 ≤ mean shear stress ≤ 1.3 x 10-2 N/m2). Expanded BMSCs on the cytodex 1 microcarriers retained multipotentiality for the range of shear stresses investigated
IODP Expedition 366 Magnetic remanence (spinner)
No full textMagnetic remanence was measured on discrete samples by an Agico JR-6A spinner magnetometer, first as natural remanent magnetization (NRM) and then after demagnetization or remagnetization steps were performed on the samples (e.g., alternating field [AF] demagnetization, thermal demagnetization [TD], or isothermal remanent magnetization [IRM])
Precise determination of aquatic plant wet mass using a salad spinner
No full textThe reliable assessment of macrophyte biomass is fundamental for ecological research and management of freshwater ecosystems. While dry mass is routinely used to determine aquatic plant biomass, wet (fresh) mass can be more practical. We tested the accuracy and precision of wet mass measurements by using a salad spinner to remove surface water from four macrophyte species differing in growth form and architectural complexity. The salad spinner aided in making precise and accurate wet mass with less than three percent error. There was also little difference between operators with a user bias estimated to be below five percent. To achieve this level of precision, only ten to 20 turns of the salad spinner are needed. Therefore, wet mass of a sample can be determined in less than one minute. We demonstrated that a salad spinner is a rapid and economical technique to enable precise and accurate macrophyte wet mass measurements and is particularly suitable for experimental work. The method will also be useful for field work in situations when sample sizes are not overly large.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author
Comparison between NRM measurement by means of an astatic magnetometer and thet of a spinner magnetometer
No full textThis paper shows that there is an excellent agreement of the measuring results on the remanent magnetic moment of rock samples due to an astatic and spinner magnetometers each other. The present author also describes some comments for the measuring procedures using these two different types of magnetometers briefly, and shows examples practically by those two methods employed
Needleless Electro-Spinner
No full textabstract: Electrospun nanofibers can be prepared from various kinds of inorganic substances by electro-spinning techniques. They have great potential in many applications including super capacitors, lithium ion batteries, filtration, catalyst and enzyme carriers, and sensors [1]. The traditional way to produce electrospun nanofibers is needle based electro-spinning [1]. However, electrospun nanofibers have not been widely used in practice because of low nanofiber production rates. One way to largely increase the electro-spinning productivity is needleless electro-spinning. In 2005, Jirsak et al. patented a rotating roller fiber generator for the mass production of nanofibers [2]. Elmarco Corporation commercialized this technique to manufacture nanofiber equipment for the production of all sorts of organic and inorganic nanofibers, and named it "NanospiderTM". For this project, my goal is to build a needleless electro-spinner to produce nanofibers as the separator of lithium ion batteries. The model of this project is based on the design of rotating roller fiber generator, and is adapted from a project at North Dakota State University in 2011 [3]
A fidget spinner for the point-of-care diagnosis of urinary tract infection
No full text© 2020, The Author(s), under exclusive licence to Springer Nature Limited.The point-of-care detection of pathogens in biological samples in resource-limited settings should be inexpensive, rapid, portable, simple and accurate. Here, we describe a custom-made fidget spinner that rapidly concentrates pathogens in 1-ml samples of undiluted urine by more than 100-fold for the on-device colorimetric detection of bacterial load and pathogen identification. In Tiruchirappalli, India, the device enabled the on-site detection of infection with the naked eye within 50 min in urine samples from 39 patients suspected of having a urinary tract infection. We also show that, in 30 clinical samples of urinary tract infection, the device can be used to perform an antimicrobial susceptibility test for the antimicrobial drugs ciprofloxacin and cefazolin within 120 min. The fidget spinner could be used in low-resource settings as an inexpensive handheld point-of-care device for the rapid concentration and detection of pathogens in urine sample
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