Dynamics of stretched flexible tubes conveying fluid

Wastewater treatment plants (WWTPs) are sources of greenhouse gases, hazardous air pollutants and offensive odors. These emissions can have negative repercussions in and around the plant, degrading the quality of life of surrounding neighborhoods, damaging the environment, and reducing employee’s overall job satisfaction. Current monitoring methodologies based on fixed gas detectors and sporadic olfactometric measurements (human panels) do not allow for an accurate spatial representation of such emissions. In this paper we use a small drone equipped with an array of electrochemical and metal oxide (MOX) sensors for mapping odorous gases in a mid-sized WWTP. An innovative sampling system based on two (10 m long) flexible tubes hanging from the drone allowed near-source sampling from a safe distance with negligible influence from the downwash of the drone’s propellers. The proposed platform is very convenient for monitoring hard-to-reach emission sources, such as the plant’s deodorization chimney, which turned out to be responsible for the strongest odor emissions. The geo-localized measurements visualized in the form of a two-dimensional (2D) gas concentration map revealed the main emission hotspots where abatement solutions were needed. A principal component analysis (PCA) of the multivariate sensor signals suggests that the proposed system can also be used to trace which emission source is responsible for a certain measurement.

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A magnetic control method for large-deformation vibration of cantilevered pipe conveying fluid

Nonlinear Dynamics ◽

10.1007/s11071-021-06662-2 ◽

2021 ◽

Author(s):

Wei Chen ◽

Lin Wang ◽

Zerui Peng

Keyword(s):

Large Deformation ◽

Control Method ◽

Deformation Vibration ◽

Magnetic Control ◽

Pipe Conveying Fluid ◽

Cantilevered Pipe ◽

Conveying Fluid

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Dynamics of axially functionally graded conical pipes conveying fluid

Journal of Mechanics ◽

10.1093/jom/ufaa030 ◽

2021 ◽

Vol 37 ◽

pp. 318-326

Author(s):

Yuzhen Zhao ◽

Dike Hu ◽

Song Wu ◽

Xinjun Long ◽

Yongshou Liu

Keyword(s):

Natural Frequency ◽

Critical Velocity ◽

Volume Fraction ◽

Differential Quadrature Method ◽

Reduction Factor ◽

Functionally Graded ◽

Function Type ◽

Pipes Conveying Fluid ◽

Volume Fraction Function ◽

Conveying Fluid

Abstract In this paper, the dynamics of axially functionally graded (AFG) conical pipes conveying fluid are analyzed. The materials are distributed along the conical pipe axis as a volume fraction function. Either the elastic modulus or the density of the AFG conical pipe is assumed to vary from the inlet to the outlet. The governing equation of the AFG conical pipe is derived using the Hamiltonian principle and solved by the differential quadrature method. The effects of the volume fraction index, volume fraction function type and reduction factor on the natural frequency and critical velocity are analyzed. It is found that for a power function volume fraction type, the natural frequency and critical velocity increase with increasing volume fraction index and clearly increase when the volume fraction index is within the range (0, 10). For an exponential function volume fraction type, the natural frequency and critical velocity change rapidly within the range (−10, 10), besides the above range the relationship between the natural frequency, critical velocity and volume fraction index is approximate of little change. The natural frequency and critical velocity decrease linearly with increasing reduction factor.

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