Study On The Aerodynamics Of Wings In The Horseshoe Bat, Rhinolophus Ferrumequinum

Bats have the unique capability of flying in mammals,bat's wing is evolved from forelimb,and the patagium connects with forelimb,body and tail.The lift that keeps bat flying is almost from interaction of air and wing,therefore,the wing can prove lift and has important effects in the process of flight.The Rhinolophus ferrumequinum is one of the species of Rhinolophidae,it can maneuver so well while low-attitude flying.Due to patagium is the main component of bat wing and its area is almost the same as wing,so the research on patagium can be seen as a study of wing.The aim of this paper is to study the patagium's aerodynamic characteristics using relevant aerodynamics theory and wind tunnel test.Research data show that wing lift is related to wind speed and angle of elevation,and the law of variation between them can be draw from graphs.The thesis mainly includes the following aspects:(1)Three-dimensional structure of bat sample.The first step is to capture the bat samples,then,the information of morphological structure of bat sample obtained by measuring and taking photos.The sample which used to study is under the conditional of natural death,and the sample must be manually handled in order to ensure the surface scanning.This process of processing includes four steps that are fixing shape,reshaping appearance,spraying photographic developer and sticking marker.And then,computer would build an original three-dimensional scanning model that was obtained by using the three-dimensional optical scanning system.The original model haves some loopholes and convex in its surface,it must be modified by image processing software to get the complete structure and skin structure model.Finally,the physical model of bat was gotten by using three-dimensional printing technology.(2)Wind tunnel test of bat model.The wind tunnel experiment is carried out on the physical model,the range of experimental elevation angle is 0 degrees ~20 degrees,and each experimental variation is 1 degree.The variation of wind speed in the wind tunnel is controlled in the range of 0m/s~6m/s,and the wind speed change value is 0.5m/s,and Record the data of wind tunnel test i(3)Data processing and analysis.Since the measurement results have a large amount of data,the regulation of bat wing aerodynamic characteristics cannot be obtained directly from the data.To express the relationship among lift,lift coefficient,wind speed,and elevation angle in the form of graph,the experimental data need to be handled and fitted.Then,after analyzing the relationship between the lift and the wind speed,angle of attack,the relationship between the lift coefficient and angle of attack,those general rules that exist in the data can be concluded.According to the physical theories,we discussed the result of the experiment.By analyzing the data,the calculated results are in following:(1)In the steady state of non-flapping wing,Rhinolophus ferrumequinum wing lift force varies with the angle of attack and speed.At the same angle of attack,with the increase of wind speed,the lift force also increasing,and the change trend increases from slow to linear.Under the same wind speed condition,the optimal angle of attack is 12 degrees,and the lift force is the maximum,and the lift force decreases slowly after the optimal angle of attack.(2)The lift coefficient changing trend with the angle of attack is also changing.The relationship between lift coefficient and angle of attack is approximately linear relationship in the small angle.Under given wind speed,the optimal angle is also 12 degrees,and lift coefficient has the maximum in this condition lift coefficient.When attack angle is greater than 12 degree,the lift coefficient decreased slowly with increasing angle of attack.At the same angle of attack,the lift coefficient of 1m/s is the largest,while the lift coefficient of other wind speed is mainly concentrated in 1~1.9.(3)The Rhinolophus ferrumequinum feeds on insects in the jungle.At low speed,it can be sensitive to avoiding obstacles and completing the hunt,the phenomenon shows that it is good at mobility,the feature meets the characteristics of the lift coefficient of low speed conditions.