Numerical Investigation of Static and Dynamic Aerodynamic Characteristics for a Guided Projectile with Fin Slot

2014 ◽  
Vol 998-999 ◽  
pp. 442-445
Author(s):  
Hua Dong Sun ◽  
Jian Qiao Yu ◽  
Yue Song Mei ◽  
Chong Liang
Keyword(s):  
Pressure Field ◽  
Fluid Dynamic ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Theoretical Research ◽  
Shape Design ◽  
Test Results ◽  
Pitch Moment ◽  
The Mean ◽  
Good Agreement

The flow field of a cruciform finned guided projectile with and without fin slot was simulated by the mean of CFD(computational fluid dynamic) numerical method. The characteristics of pressure field distribution without and different widths slots were calculated and compared. The influence of fin slot to the aerodynamic characteristics such as drag, lift, roll moment, pitch moment static aerodynamic characteristics as well as pitch, roll damping moment dynamic aerodynamic characteristics were emphasized in different angle of attack. The numerical results were certified by the good agreement between the wind tunnel test results. Important reference was provided to theoretical research and engineering for guided projectile shape design.

Influence of Mix Proportions on Water Absorption of RCA Concretes

2016 ◽  
Vol 722 ◽  
pp. 187-194
Author(s):  
Roman Jaskulski ◽  
Paweł Las ◽  
Wojciech Kubissa
Keyword(s):  
Water Absorption ◽  
Probabilistic Models ◽  
Recycled Aggregate ◽  
Test Results ◽  
Mean Values ◽  
Concrete Mixtures ◽  
The Subject ◽  
The Mean ◽  
Best Fit ◽  
Good Agreement

The subject of the work is to develop probabilistic models defining the water absorption of concretes made ​​with the use of recycled aggregate (RCA). For the study 16 series of concrete mixtures were made with a 50 mass% share of recycled aggregate in the whole amount of coarse aggregate. The analysis of test results aimed at formulating a relationship between water absorption value and selected parameters of the composition of concretes. The objective was to find a model giving the best fit between calculated values and test results. Formulated models were then used in probabilistic modeling absorption using a Monte Carlo simulation. The results indicate a good agreement of the mean values of water absorption and possibility of good fitting of the standard deviation if an additional summand is introduced into the model.

Nonlinear Aeroelastic Behaviour of Compliant Airfoils

2009 ◽  
Author(s):  
Ghalib Y. Thwapiah ◽  
Flavio L. Campanile
Keyword(s):  
Wind Tunnel ◽  
Large Deformations ◽  
Wind Tunnel Test ◽  
Test Results ◽  
Linear Approach ◽  
Innovative Idea ◽  
Compliant Systems ◽  
Observed Behaviour ◽  
Analytic Prediction ◽  
Good Agreement

Since begin of the aviation and up to the present times, airfoils have always been built as rigid structures. They are designed to fly under their divergence speed in order to avoid static aeroelastic instabilities and the resulting large deformations which are not compatible with the typically low compliance of such airfoils. In recent years, research on airfoil morphing has generated interest in innovative ideas like the use of compliant systems, i.e. systems built to allow for large deformations without failure, in airfoil construction. Such systems can operate in the neighbourhood of divergence and take advantage of large aeroelastic servo-effects. This, in turn, could allow compact, advanced actuators to control the airfoil’s deformation and loads, and hence complement or even replace conventional flaps. In order to analyze and design such compliant, active aeroelastic structures a non-linear approach to static aeroelastic is needed, which takes into account the effect of large deformations on aerodynamics and structure. Such an analytical approach is presented in this paper and applied to a compliant passive airfoil as the preliminary step to the realisation of a piezoelectrically driven, active aeroelastic airfoil. Wind-tunnel test results are also presented and compared with the analytic prediction. The good agreement and the observed behaviour in the wind tunnel give confidence in the potential of this innovative idea.

The Dip-Forming Process

1965 ◽  
Vol 87 (1) ◽  
pp. 1-12 ◽  
Author(s):  
G. Horvay
Keyword(s):  
Material Properties ◽  
Continuous Process ◽  
Slab Thickness ◽  
Test Results ◽  
Forming Process ◽  
A Value ◽  
The Mean ◽  
Time Of Travel ◽  
Slab Melt ◽  
Good Agreement

A cool slab of metal when dipped into the bath of a molten metal first freezes metal from the bath; then—if kept there long enough—the frozen crust and the slab melt out. The same result is obtained in a continuous process where the slab is pulled through the melt. In this paper a theory is developed for the process, assuming that the material properties of bath and slab are the same. The governing partial differential equation is established, and is approximated by four-node (“3-channel”) and two-node (“1-channel”) difference-differential equations. It is shown that when the slab is passed through the bath at a speed exceeding a value 5 of the Peclet number p, it is adequate to regard the slab in the calculations as suddenly dipped into the bath and then kept there for a time equal to the time of travel through the bath. The solutions of the 1-channel equations are presented in the form of dimensionless curves which give the mean temperature of the slab as function of position and show the growth and decrease of the slab thickness. Good agreement is obtained with available test results for dip-formed copper.

scholarly journals Convergence of transonic wind tunnel test results of the AGARD-B standard model

2020 ◽  
Vol 48 (4) ◽  
pp. 761-769
Author(s):  
Dijana Damljanović ◽  
Đorđe Vuković ◽  
Goran Ocokoljić ◽  
Boško Rašuo
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Test Results ◽  
Aerodynamic Coefficients ◽  
Supersonic Wind Tunnel ◽  
Mean Values ◽  
Wide Range ◽  
Production Technologies ◽  
Mach Numbers

AGARD-B is a widely-used configuration of a standard wind tunnel model. Beside its originally intended application for correlation of data from supersonic wind tunnel facilities, it was tested in a wide range of Mach numbers and, more recently, used for assessment of wall interference effects, validation of computational fluid dynamics codes and validation of new model production technologies. The researchers and wind tunnel test engineers would, naturally, like to know the "true" aerodynamic characteristics of this model, for comparison with their own work. Obviously, such data do not exist, but an estimate can be made of the dispersion of test results from various sources and of the probable "mean" values of the aerodynamic coefficients. To this end, comparable transonic test results for the AGARD-B model at Mach numbers 0.77, Mach 1.0 and Mach 1.17 from six wind tunnels were analyzed and average values and dispersions of the aerodynamic coefficients were computed.

Rancang Bangun Piranti Lunak Pengolah Data Pasca Pengujian Terowongan Angin Kecepatan Rendah Indonesia

2016 ◽  
Vol 7 (2) ◽  
pp. 131-138
Author(s):  
Ivransa Zuhdi Pane
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Test Results ◽  
Effective Solution ◽  
Post Processing ◽  
Prototype Development ◽  
Design Activities ◽  
Index Terms ◽  
Test Objects ◽  
Processing Requirement

Data post-processing plays important roles in a wind tunnel test, especially in supporting the validation of the test results and further data analysis related to the design activities of the test objects. One effective solution to carry out the data post-processing in an automated productive manner, and thus eliminate the cumbersome conventional manual way, is building a software which is able to execute calculations and have abilities in presenting and analyzing the data in accordance with the post-processing requirement. Through several prototype development cycles, this work attempts to engineer and realize such software to enhance the overall wind tunnel test activities. Index Terms—software engineering, wind tunnel test, data post-processing, prototype, pseudocode

scholarly journals Spine Examination during COVID-19 Pandemic via Video Consultation

2021 ◽  
Author(s):  
Tom Jansen ◽  
Martin Gathen ◽  
Amadeo Touet ◽  
Hans Goost ◽  
Dieter Christian Wirtz ◽  
...  
Keyword(s):  
Pain Intensity ◽  
Range Of Motion ◽  
Test Results ◽  
Risk Of Infection ◽  
Face To Face ◽  
Reliable Tool ◽  
Provocation Tests ◽  
Active Range Of Motion ◽  
Video Consultation ◽  
Good Agreement

Abstract Introduction During the current COVID-19 pandemic video consultations are increasingly common in order to minimize the risk of infection for staff and patients. The aim of this study was to evaluate the feasibility of a spine examination via video. Methods A total of 43 patients were recruited. Each participant underwent a video-based (VB) and a conventional face-to-face (FTF) spine examination. Pain intensity, active range of motion, inspection, a neurophysiologic basic exam and provocations tests were evaluated using video-based and face-to-face methods. Results The intra-rater reliability (IRR) was measured between both examinations. Good to very good IRR values were obtained in inspection (Kappa between 0,752 und 0,944), active range of motion and basic neurophysiological examination (Kappa between 0,659 und 0,969). Only moderate matches were found in specific provocation tests (Kappa between 0,407 und 0,938). A video-based spine examination is a reliable tool for measuring pain intensity, active range of motion and a basic neurophysiologic exam. Conclusion A basic spine examination during a video consultation is possible. A good agreement of the test results between video-based and face-to-face examination could be found.

scholarly journals Ex vivo evaluation of a multilayered sealant patch for watertight dural closure: cranial and spinal models

2021 ◽  
Vol 32 (8) ◽  
Author(s):  
A. Kinaci ◽  
S. van Thoor ◽  
S. Redegeld ◽  
M. Tooren ◽  
T. P. C. van Doormaal
Keyword(s):  
Ex Vivo ◽  
Resistance Test ◽  
Burst Pressure ◽  
Cerebrospinal Fluid Leakage ◽  
Computer Assisted ◽  
Dural Defect ◽  
Test Results ◽  
Physiological Conditions ◽  
Dural Attachment ◽  
The Mean

AbstractCerebrospinal fluid leakage is a frequent complication after cranial and spinal surgery. To prevent this complication and seal the dura watertight, we developed Liqoseal, a dural sealant patch comprising a watertight polyesterurethane layer and an adhesive layer consisting of poly(DL-lactide-co-ε-caprolactone) copolymer and multiarmed N-hydroxylsuccinimide functionalized polyethylene glycol. We compared acute burst pressure and resistance to physiological conditions for 72 h of Liqoseal, Adherus, Duraseal, Tachosil, and Tisseel using computer-assisted models and fresh porcine dura. The mean acute burst pressure of Liqoseal in the cranial model (145 ± 39 mmHg) was higher than that of Adherus (87 ± 47 mmHg), Duraseal (51 ± 42 mmHg) and Tachosil (71 ± 16 mmHg). Under physiological conditions, cranial model resistance test results showed that 2 of 3 Liqoseal sealants maintained dural attachment during 72 hours as opposed to 3 of 3 for Adherus and Duraseal and 0 of 3 for Tachosil. The mean burst pressure of Liqoseal in the spinal model (233 ± 81 mmHg) was higher than that of Tachosil (123 ± 63 mmHg) and Tisseel (23 ± 16 mmHg). Under physiological conditions, spinal model resistance test results showed that 2 of 3 Liqoseal sealants maintained dural attachment for 72 hours as opposed to 3 of 3 for Adherus and 0 of 3 for Duraseal and Tachosil. This novel study showed that Liqoseal is capable of achieving a strong watertight seal over a dural defect in ex vivo models.

scholarly journals Aerodynamics of smooth and rough square-section prisms at incidence in very high Reynolds-number cross-flows

2021 ◽  
Vol 62 (3) ◽  
Author(s):  
Nils Paul van Hinsberg
Keyword(s):  
Reynolds Number ◽  
Cross Sections ◽  
Reynolds Numbers ◽  
Circular Cylinders ◽  
Surface Boundary ◽  
Experimental Proof ◽  
Surface Boundary Layer ◽  
Pitch Moment ◽  
The Mean ◽  
High Reynolds

Abstract The aerodynamics of smooth and slightly rough prisms with square cross-sections and sharp edges is investigated through wind tunnel experiments. Mean and fluctuating forces, the mean pitch moment, Strouhal numbers, the mean surface pressures and the mean wake profiles in the mid-span cross-section of the prism are recorded simultaneously for Reynolds numbers between 1$$\times$$ × 10$$^{5}$$ 5 $$\le$$ ≤ Re$$_{D}$$ D $$\le$$ ≤ 1$$\times$$ × 10$$^{7}$$ 7 . For the smooth prism with $$k_s$$ k s /D = 4$$\times$$ × 10$$^{-5}$$ - 5 , tests were performed at three angles of incidence, i.e. $$\alpha$$ α = 0$$^{\circ }$$ ∘ , −22.5$$^{\circ }$$ ∘ and −45$$^{\circ }$$ ∘ , whereas only both “symmetric” angles were studied for its slightly rough counterpart with $$k_s$$ k s /D = 1$$\times$$ × 10$$^{-3}$$ - 3 . First-time experimental proof is given that, within the accuracy of the data, no significant variation with Reynolds number occurs for all mean and fluctuating aerodynamic coefficients of smooth square prisms up to Reynolds numbers as high as $$\mathcal {O}$$ O (10$$^{7}$$ 7 ). This Reynolds-number independent behaviour applies to the Strouhal number and the wake profile as well. In contrast to what is known from square prisms with rounded edges and circular cylinders, an increase in surface roughness height by a factor 25 on the current sharp-edged square prism does not lead to any notable effects on the surface boundary layer and thus on the prism’s aerodynamics. For both prisms, distinct changes in the aerostatics between the various angles of incidence are seen to take place though. Graphic abstract

Design of combined brake system for light weight scooters

2021 ◽  
pp. 095440702110240
Author(s):  
Yuan-Ting Lin ◽  
Chyuan-Yow Tseng ◽  
Jao-Hwa Kuang ◽  
Yeong-Maw Hwang
Keyword(s):  
Ride Comfort ◽  
Brake System ◽  
Force Distribution ◽  
Test Results ◽  
Systematic Method ◽  
Braking Performance ◽  
Evaluation Indexes ◽  
Low Costs ◽  
Braking Force ◽  
Good Agreement

The combined brake system (CBS) is a mechanism that links the front and rear brakes for scooters. For two-wheeled scooters, a CBS with appropriate braking force distribution can reduce the risk of crashing accidents due to insufficient driving proficiency. The design of the braking force distribution for a CBS is challenging to the designer because it has to fulfill many requirements such as braking performance, ride comfort, reliability, and low costs. This paper proposes a systematic method to optimize the parameters of CBS. The evaluation indexes for the design are first discussed. The steps to determine the critical parameter to meet the indexes and a method to predict braking performance are developed. Finally, driving tests are carried out to verify the effectiveness of the proposed method. Experimental results showed that the deceleration of the tested scooter equipped with the designed CBS achieves an average mean fully developed deceleration (MFDD) of 5.246 m/s2, higher than the homologation requirement. Furthermore, the proposed method’s prediction of braking performance is in good agreement with the test results, with errors <1%.

scholarly journals Investigation of the Time Dependence of Wind-Induced Aeroelastic Response on a Scale Model of a High-Rise Building

2021 ◽  
Vol 11 (8) ◽  
pp. 3315
Author(s):  
Fabio Rizzo
Keyword(s):  
Wind Tunnel ◽  
Time Dependence ◽  
Wind Tunnel Test ◽  
Structural Response ◽  
Cumulative Distribution ◽  
Scale Model ◽  
Acquisition Time ◽  
Test Results ◽  
High Rise ◽  
High Rise Building

Experimental wind tunnel test results are affected by acquisition times because extreme pressure peak statistics depend on the length of acquisition records. This is also true for dynamic tests on aeroelastic models where the structural response of the scale model is affected by aerodynamic damping and by random vortex shedding. This paper investigates the acquisition time dependence of linear transformation through singular value decomposition (SVD) and its correlation with floor accelerometric signals acquired during wind tunnel aeroelastic testing of a scale model high-rise building. Particular attention was given to the variability of eigenvectors, singular values and the correlation coefficient for two wind angles and thirteen different wind velocities. The cumulative distribution function of empirical magnitudes was fitted with numerical cumulative density function (CDF). Kolmogorov–Smirnov test results are also discussed.

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