BACKGROUND: Noise at production site or at any other place where technical equipment operates is a huge issue. It has a strong negative effect on human nervous system, reduces average lifespan and causes a number of severe diseases. That is why reduction of noise, produced by pumps, is one of the current priorities of hydraulic engineering. AIMS: In this study, the experimental research of sound transmission through an operating pump and a non-operating pump was carried out. The aim of the research is to find out, whether the last stage of a multistage pump is the main source of hydrodynamic noise (HDN) in pressure line (or the first stage in suction line), or all stages somehow contribute to HDN. METHODS: The experiment was carried out on the TsN-2 two-stage impeller pump. In order to generate a sinusoidal signal, an imbedded generator, a vibration test rig and a power amplifier were used. Data acquisition for measurement of HDN and vibrations was performed with use of a conditioning amplifier, a hydrophone and an accelerometer. A 4-channel spectrum analyzer served as a device for processing the studied signal. In addition, a theoretical calculation, considering some physical assumptions, was carried out in order to obtain a more general and accurate concept. RESULTS: After completing the experiment, hydrodynamic noise levels and differences for three cases were obtained. These cases are for the switched-on pump, the switched-off pump and for the pump with the removed stage. The data obtained with hydrophones (hydrodynamic noise levels) was correlated with the data obtained with accelerometers (vibration levels). As the correlated data analysis result, the sound insolation distribution over the spectrum was obtained. CONCLUSIONS: According to the study results, it can be concluded that the absence of one of two stages ambiguously affected on the sound-insolation properties of the pump. Moreover, no firm conclusions can be drawn about the pump operation influence on the change in its sound-insolation properties.
Increase in the service life and noise reduction in pumps is an important area in modern pump engineering. An attempt was made to introduce conjugate calculations in verifying correct operation of the mathematical model as the first step and identifying the main oscillation frequencies of the pump housing subsequently. The FSI interface was used in conjugate calculations at the boundary between liquid and solid media. The obtained oscillation signals were analyzed using the Fourier analysis to identify the main parasitic frequencies in the pump. It was expected that the main parasitic frequency would be the blade frequency. As a result of calculations, it became possible to verify correct operation of the mathematical model by applying it to the simplest model of a glass, which behavior could be easily explained. The mathematical model was tested on cantilever and multistage pumps, demonstrated good results and made it possible to establish that blade frequency was the main oscillation frequency.
BACKGROUND: The study of factors affecting the vibroacoustic characteristics of pumps is one of the main areas of development in the current pump industry. Improvement of these characteristics allows to extend the service life of pumps by means of vibration levels reduction as well as to decrease the noise level. AIMS: In this study, the attempt to optimize the flow part of a multi-stage pump was made in order to obtain acceptable noise, vibration and harshness (NVH) characteristics in two operation modes that are different front the optimal one. METHODS: As the result of the study, it was found that changing these parameters in favour of NVH has a negative impact on the pump efficiency and vice versa. Thereby the optimal balance between these parameters should be found. The optimization was performed with the method of research of the parameter space with use of LP-tau sequences. The following elements were chosen as the optimization parameters: the area at the entrance to downstream, the angle of guide vanes at the entrance to the downstream, the width of rotor at the outlet, the angle of rotor vanes at the inlet and the outlet, the wrap angle of rotor vane. Decrease of the area of the graph of pressure pulsation spectrum was chosen as the optimization criteria. The mathematical model was verified with two designs of the flow part produced and tested earlier. The first sample has an overstated rate of the NVH spectrum in the area of high frequencies, the second sample has an overstated rate of the NVH spectrum in the area of low frequencies. RESULTS: The compiled mathematical model proved its good quality, showing the same results, which allows to speak about the admissibility of its use for optimization of the flow parts of pumps. CONCLUSIONS: This study will be useful for specialists in the field of vane hydraulic machines design.
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