Fig.1

Distribution of sand and dust motion in hovering helicopter［9］

Fig.2

Blade structural grid

Fig.3

Spatial grid

Fig.4

Spatial grid encryption

Table 1

Parameters of UH-60A standard model rotor

Fig.5

Variation curves of tension coefficient and power coefficient with number of grids

Fig.6

Radial distribution of lift coefficients for single blade

Fig.7

Variation of hover efficiency with tension coefficient

Table 2

Blade parameters of experiment model

Fig.8

Test wind speed measurement PIV method

Fig.9

Comparison of ground jet velocity test and calculation （h=1R）

Fig.10

Comparison of ground jet velocity test and calculation （h=1.4R）

Fig.11

Variation of hover efficiency and forward lift-drag ratio with blade down reverse positions

Fig.12

Variation of hover efficiency and forward lift-drag ratio with blade lower diagonal angles

Fig.13

Definition of coordinate system

Fig.14

Comparison of blade tip vortex circumferential velocities with different blade lower diagonal angles

Fig.15

Variation of ground jet velocity with height at different blade down reverse positions

Fig.16

Vorticity diagrams of flow field with different blade lower diagonal angles

Fig.17

Distribution of sand and dust with different blade lower diagonal angles

Fig.18

Schematic diagram of ground sand trace

Fig.19

Division of spatial flow field

Fig.20

Variation curves of sand particle quantity with radial position

Table 3

Aerodynamic design schemes of rotor

参数	方案1	方案2
半径/m	1.5	1.5
实度	0.099	0.099
片数	5	5
桨尖形状	抛物线桨尖	类BERP桨尖

Fig.21

Curves of collective pitch-tension coefficient

Fig.22

Curves of hovering efficiency-tension coefficient

Fig.23

Comparison of blade tip vortex circumferential velocities with different schemes

Fig.24

Variation of ground jet velocity with height at different radial positions

Fig.25

Top view of sand blowing in Scheme 1 and Scheme 2

Fig.26

Drivers view of sand blowing in Scheme 1 and Scheme 2

Fig.27

Variation curves of sand and dust particle quantity with radial position in two schemes

Fig.28

Velocity streamlines of forward flight flow field in Scheme 1 and Scheme 2

Fig.29

Sand blowing characteristics of forward flight flow field in Scheme 1 and Scheme 2