5 Experimental Fluid Mechanics
349
Table 5.2 Related variables prototype and model values (Re criterion)
Name
Prototype value
Model value
Scale
Propeller diameter D(m)
4.0
0.800
5
Propeller rotate speed n (rpm)
1075
60100
1/25
Standard takeoff speed V 0 (km/h)
258.0
1290
1/5
Table 5.3 Related variables prototype and model values (St criterion)
Name
Prototype value
Model value
Scale
Propeller diameter D(m)
4.0
0.800
5
Propeller rotate speed n (rpm)
1075
2150
0.5
Standard takeoff speed V 0 (km/h)
258.0
103.2
2.5
Accordingly, the similar parameters of the model obtained and prototype
are given in Table 5.2.
(3) Design the model according to the Sh number criterion
The design set λ L = 5.0, wind tunnel model propeller speed is limited, set
λ n = 1/2, n m = 2n p
Obtained by the Strouhal number similarity criterion
λ V
λ L λ n
= 1, λ V = λ L λ n = 5/2 = 2.5
Accordingly, the similar parameters of the model obtained and prototype
are given in Table 5.3.
5.4 Flow Visualization Measurement Technique
Fluid mechanics experiments generally include flow visualization and flow
measurement methods. The main task of the flow visualization experiment is
to visualize the fluid flow process, while the main task of the flow measurement experiment is to obtain the quantitative information of the fluid flow
process, which complement each other and are an integral part of the experimental fluid dynamics. Through various flow visualization and measurement
experiments, people can understand complex flow phenomena, explore physical mechanisms and motion laws, and provide scientific basis for establishing
349
Table 5.2 Related variables prototype and model values (Re criterion)
Name
Prototype value
Model value
Scale
Propeller diameter D(m)
4.0
0.800
5
Propeller rotate speed n (rpm)
1075
60100
1/25
Standard takeoff speed V 0 (km/h)
258.0
1290
1/5
Table 5.3 Related variables prototype and model values (St criterion)
Name
Prototype value
Model value
Scale
Propeller diameter D(m)
4.0
0.800
5
Propeller rotate speed n (rpm)
1075
2150
0.5
Standard takeoff speed V 0 (km/h)
258.0
103.2
2.5
Accordingly, the similar parameters of the model obtained and prototype
are given in Table 5.2.
(3) Design the model according to the Sh number criterion
The design set λ L = 5.0, wind tunnel model propeller speed is limited, set
λ n = 1/2, n m = 2n p
Obtained by the Strouhal number similarity criterion
λ V
λ L λ n
= 1, λ V = λ L λ n = 5/2 = 2.5
Accordingly, the similar parameters of the model obtained and prototype
are given in Table 5.3.
5.4 Flow Visualization Measurement Technique
Fluid mechanics experiments generally include flow visualization and flow
measurement methods. The main task of the flow visualization experiment is
to visualize the fluid flow process, while the main task of the flow measurement experiment is to obtain the quantitative information of the fluid flow
process, which complement each other and are an integral part of the experimental fluid dynamics. Through various flow visualization and measurement
experiments, people can understand complex flow phenomena, explore physical mechanisms and motion laws, and provide scientific basis for establishing