Study On Propagation Characteristics And Measurement Of Acoustic Waves In Constrained Fluids

Acoustic wave is a kind of mechanical wave,which is often used for fluid flow velocity detection and has a wide range of applications in the fields of medicine and flaw detection.In traditional acoustic wave detection applications,most of them are measured by the time difference method.In the measurement process,the imaginary sound waves are propagated in the form of plane waves.When the propagation distance is relatively close and constrained,the mathematical model of plane wave propagation is no longer suitable for such cases.It is necessary to analyze the propagation law of sound waves in the near-field environment in combination with wave theory.To this end,the paper analyzes the propagation characteristics of spherical acoustic waves in near-field space,and designs a set of measurement system combining software and hardware to verify the inference results.In order to ensure that the measurement accuracy of the system can meet the experimental requirements,this paper studies and establishes the mathematical model of acoustic resonance to establish the entire structure of the experimental platform.Firstly,this paper starts from the basic theory of sound wave propagation and combines wave theory to derive the wave equations of spherical acoustic waves propagating in infinite space,semi-infinite space and constrained space.And using MATLAB to simulate and analyze the acoustic wave equation after the deduction.In an ideal state,get a simulation model in which a spherical acoustic wave is reflected and superimposed multiple times between two parallel plates to produce a resonance phenomenon.Under the constraint space model,comparing the calculated simulation model with the acoustic basics,analysis the relationship between the resonant sound field and the fluid flow rate.Secondly,integrating microelectronics technology,designed a set of ultrasonic testing system for test verification.On a theoretical basis,this article ensure that use Exynos4412 to complete functions such as data processing and peripheral communication.System use master-slave control structure,realizing ARM-based resonant ultrasonic detection system.Hardware circuit design mainly contains that:ultrasonic transducer drive circuit,signal processing circuit,data acquisition circuit.System software design mainly adopts C language to realize control program design.It realize algorithm compensation,digital filtering,data processing,data saving and transmission.Research design and experimental test results show that sound waves will resonate in such constrained spaces as parallel plates.Under the condition that the sound wave continues to emit,it will form a stable sound field.There will be a specific functional relationshipbetween the flow velocity in space and the sound pressure amplitude and acoustic phase of a stable sound field in space.Ultrasonic testing can be used to indirectly obtain the fluid velocity in the current time space.It has certain application prospects and reference value for the study of the propagation characteristics of acoustic waves in near-field space.