Numerical study of a variable camber plunge airfoil under wind gust condition

Zhu, Jianyang; Jiang, Lin; Zhao, Hui; Tao, Bo; Lei, Bin

doi:10.1007/s12206-015-1015-z

Cited by 20 publications

(12 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is as well important to emphasize that the linear chains of starch tend to retrograde in aqueous paste through hydrogen bonding and align themselves in a parallel manner, thus form three‐dimensional arrays . Therefore, the starch sized onto warp yarns cannot be simply washed away by water and must be subjected to chemical treatments or enzymatic degradations . Nowadays, this is usually done in hot water in the presence of enzyme, alkali, or oxidant.…”

Section: Resultsmentioning

confidence: 99%

“…Hank sizing was performed according to a method described in the literature only with an exception in paste concentration of the starch. Hank cotton yarns were impregnated with a cooked starch aqueous paste (6% by wt.)…”

Section: Methodsmentioning

confidence: 99%

“…Hank cotton yarns were impregnated with a cooked starch aqueous paste (6% by wt.) for 30 min according to a method described in the literature . Then the impregnated yarns were put into an open‐meshed fabric bag and the excessive paste was squeezed off.…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Desizability of the Grafted Starches Used as Warp Sizing agents

Liu

Zhu

et al. 2017

Starch Stärke

View full text Add to dashboard Cite

An attempt is made to examine the effect of the consitituent units in the branches grafted onto the backbones of starch on the desizability of grafted starches for warp sizing. The starches investigated include starch‐g‐polyacrylamide, starch‐g‐poly(acrylic acid), starch‐g‐polyacrylate, and starch‐g‐polymethacrylate, which are synthesized via graft copolymerization in water using Fe2+‐H2O2 initiators. The desizability is evaluated by enzyme, alkali, and oxidant desizings in terms of desizing efficiency, water swellability of starch film, and the time for breaking the starch film in water. It is found that the constituent units play an important role in desizability. Hydrophilic units are superior to hydrophobic ones in improving desizability. For the (meth)acrylate units, the increase in the number of carbon atoms in alkyl esters and the presence of α‐methyl show adverse impact on desizability. An increase in the grafting ratio of starch‐g‐polyacrylamide favors improvement of the desizabity whereas the increase in the ratio of starch‐g‐poly(methyl acrylate) reduces the desizabity. Of the three desizing methods considered here, oxidant and enzyme desizings have superior desizability to alkali one.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Desizability of the Grafted Starches Used as Warp Sizing agents

Liu

Zhu

et al. 2017

Starch Stärke

View full text Add to dashboard Cite

show abstract

“…2D numerical study of pure and sinusoidal hovering asymmetric flight under zero mean gust using a Lagrangian particle-based algorithm [30] *For correspondence reported that mean lift forces exhibited improvements with an increase in fluctuation of the gust amplitude. 2D numerical studies of flow physics in the vicinity of a variable camber plunge airfoil under gusty conditions [31] revealed that variable camber airfoils were capable of mitigating undesirable load on flapping wings under gusty conditions. These studies revealed that for a set of camber shapes, the force pattern was not affected by gust within a certain frequency or gust amplitude band.…”

Section: Introductionmentioning

confidence: 99%

Recurrence studies of insect-sized flapping wings in inclined-stroke plane under gusty conditions

Mathur

Vengadesan

2019

Sādhanā

View full text Add to dashboard Cite

Global recurrence plots (GRPs) and windowed recurrence quantification analysis (WRQA) are two recurrence paradigms which find wide applications to detect the onset of instability in a dynamic system. The present work reports the attempt to employ these recurrence paradigms to assess the effect of frontal gust on the force patterns of an insect-sized flapping wing in the inclined-stroke plane. Horizontal and vertical forces generated by the flapping wing in the presence of gusts of the form u G u w ¼ u 1 u w þ u g u w sin 2p f g f w t were numerically estimated in the 2D reference frame for Re = 150. Nine gusts with combinations of the ratio of gust frequency to wing's flapping frequency, f g /f w = 0.1, 0.5 and 1 and ratio of gust velocity amplitude to root mean square averaged flapping velocity, u g /u w = 0.1, 0.5 and 1 were considered. Recurrence studies of the forces were carried out to find out the gusty condition, which would trigger an onset of unstable behaviour. Studies indicated a possible onset of instability in the force patterns for gust with f g /f w = 0.1 and u g /u w = 1. The onset of unstable behaviour was prominently captured by WRQA of the vertical force coefficient based on determinism (DET) and laminarity (LAM) series.

show abstract

“…The fluid-elastic coupling adds to the difficulty level. Although, wind gusts encompass a broad range of frequencies and amplitudes, majority of the available studies con-MATEC Web of Conferences 148, 08001 (2018) https://doi.org/10.1051/matecconf/201814808001 ICoEV 2017 sider a simplified model of harmonic gust with a single frequency [10,16]. The aerodynamic performance of flexible airfoils under irregular flow-fluctuations is still not well understood.…”

Section: Introductionmentioning

confidence: 99%

Stochastic Bifurcation Analysis of an Elastically Mounted Flapping Airfoil

2018

View full text Add to dashboard Cite

Abstract. The present paper investigates the effects of noisy flow fluctuations on the fluid-structure interaction (FSI) behaviour of a span-wise flexible wing modelled as a two degree-of-freedom elastically mounted flapping airfoil. In the sterile flow conditions, the system undergoes a Hopf bifurcation as the free-stream velocity exceeds a critical limit resulting in a stable limit-cycle oscillation (LCO) from a fixed point response. On the other hand, the qualitative dynamics changes from a stochastic fixed point to a random LCO through an intermittent state in the presence of irregular flow fluctuations. The probability density function depicts the most probable system state in the phase space. A phenomenological bifurcation (P-bifurcation) analysis based on the transition in the topology associated with the structure of the joint probability density function (pdf) of the response variables has been carried out. The joint pdf corresponding to the stochastic fixed point possesses a Dirac delta function like structure with a sharp single peak around zero. As the mean flow speed crosses the critical value, the joint pdf bifurcates to a crater-like structure indicating the occurrence of a P-bifurcation. The intermittent state is characterized by the co-existence of the unimodal as well as the crater like structure.

show abstract

Numerical study of a variable camber plunge airfoil under wind gust condition

Cited by 20 publications

References 12 publications

Desizability of the Grafted Starches Used as Warp Sizing agents

Desizability of the Grafted Starches Used as Warp Sizing agents

Recurrence studies of insect-sized flapping wings in inclined-stroke plane under gusty conditions

Stochastic Bifurcation Analysis of an Elastically Mounted Flapping Airfoil

Contact Info

Product

Resources

About