Experimental set-up for investigation of fault diagnosis of a centrifugal pump

Centrifugal pumps are complex machines which can experience different types of fault. Condition monitoring can be used in centrifugal pump fault detection through vibration analysis for mechanical and hydraulic forces. Vibration analysis methods have the potential to be combined with artificial intelligence systems where an automatic diagnostic method can be approached. An automatic fault diagnosis approach could be a good option to minimize human error and to provide a precise machine fault classification. This work aims to introduce an approach to centrifugal pump fault diagnosis based on artificial intelligence and genetic algorithm systems. An overview of the future works, research methodology and proposed experimental setup is presented and discussed. The expected results and outcomes based on the experimental work are illustrated

Preliminary investigation of culvert outlet baffle block geometry and energy dissipation

One method used to attenuate high-energy flow at culvert outlets, is the construction of baffle blocks. Baffle blocks are devices, generally of simplistic geometry, that impact the flow and reduce energy. The current baffle design used by the WVDOH has in some instances experienced problems with excessive sedimentation to the extent of causing culvert failure. The purpose of this investigation was to construct a testing device to allow for the testing of physical culvert and baffle block models and produce a preliminary design that would perform more efficiently than the current design. The new design would need to meet the following criteria: (1) Reasonable construction on site; (2) Economically feasible; (3) Applicability to various culvert sizes and flowrates; (4) Self cleaning and low maintenance; and (5) Re-establish natural flow conditions downstream of the outlet.;Several models were constructed and tested. This thesis reviews the construction of all experimental equipment and the development of a preliminary design

Preliminary investigation of energy dissipation at culvert outlets using a riprap step

One method used to attenuate high-energy flow at culvert outlets is the construction of a riprap energy dissipator. The current riprap design used by the WVDOH experiences problems with excessive sedimentation and is only applicable at culvert outlets where the flow velocity is low. The purpose of this investigation was to construct a testing device to allow for the testing of physical models and produce a preliminary riprap step design that would perform more effectively than the current design. The new design proposed meets the following criteria. It is: (1) Easily constructed on site using available materials; (2) Economically efficient; (3) Applicable to various culvert sizes and flowrates; (4) Self cleaning and requires low maintenance; (5) Able to re-establish natural flow conditions downstream of the outlet. Several model steps were constructed and tested. This thesis reviews the construction of all experimental equipment and the development of a preliminary design

Experimental and Numerical Investigations on the Cavitation Phenomenon in a Centrifugal Pump

Centrifugal pumps play an important role in engineering applications since they are commonly used in industrial and residential systems, covering wide range of flow rates. Improving the performance of turbomachines such as the centrifugal pumps can be difficult to achieve, since the flow is turbulent with unsteady behaviour and cavitation. Cavitation is a complex phenomenon that is commonly considered as one of the main causes of deterioration in pump performance. Diagnosing cavitation and detecting its level of severity are essential for maintaining the pump’s reliability. Continuous condition monitoring of the pump is important to increase its operational life, decrease maintenance costs and hence, enhance the reliability of the pump. Early detection of cavitation can also improve the pump’s life expectancy by adopting various preventative actions. In this research, the first technique used for detecting cavitation is Computational Fluid Dynamics because it can provide suitable visualisation and reasonably accurate information, regarding the behaviour of fluid flow in the pump. In this work, both qualitative and quantitative analyses were carried out through a wide range of operating conditions and different geometrical configurations of a centrifugal pump under single-phase and cavitation conditions. Both, global and local flow field characteristics were investigated for better understanding. For qualitatively analysis, contours of static pressure and velocity magnitude under single-phase conditions and vapour volume fractions contour under cavitation conditions were adopted. On the other hand, the head and pressure variation in both time and frequency domains were analysed for qualitative analysis. The results showed that, as the pump rotational speed, number of impeller blades, and the outlet impeller diameter increase the head of the pump increases as well as the occurrence of cavitation. Based on the extensive numerical investigations for variety of operational and geometrical parameters, novel semi-empirical correlations under single-phase and cavitation conditions for the pump head and power coefficients were developed. Developments of aforementioned relations were carried out using multiple regression analysis technique. The second and third research areas consist of an extensive experimental analysis on the effects of operating conditions on the pump performance to predict cavitation using vibration and acoustic signature analyses. Detailed experimental investigations were carried out for the detection and diagnosis of cavitation, with the aid of sophisticated equipment and sensors. The condition monitoring was experimentally carried out in both, time and frequency domains analyses. Time domain method was applied to analyse the vibration and acoustic signals in time waveform analysis (TWFA). These signatures were analysed using different statistical parameters such as peak, root mean square (RMS), peak-to-peak and variance. In addition, transforming and analysing these signals in frequency domain was made by using Fast Fourier Transform technique. Analyses of these signals in frequency domain were also carried out using different statistical parameters such as mean and RMS features under wide various frequency ranges. The results revealed that using cavitation detection index (CDI) was a powerful technique, which can be used in both time and frequency domains for detecting cavitation and comparing the sensitivity of the vibration and acoustic techniques in estimating earlier stage of cavitation. Moreover, vibration technique was more sensitive to detect different levels of cavitation, especially inception of cavitation as compared to acoustic technique. This research has also found that the range of frequency between 0Hz to 15kHz was more sensitive to detect cavitation in the pump at the early stages. However, further investigation indicated that a frequency range of 1Hz to 2kHz was also effective on predicting the cavitation. Based on these findings, it can be suggested to use low range of frequency sensors (accelerometer and microphone) to capture the cavitation phenomenon instead of higher range of frequency, which are more expensive. In addition, it was found that all three techniques adopted in this investigation such as; CFD, vibration and acoustic techniques are well capable to analyse cavitation behaviours under different operating conditions. Moreover, it was observed that the numerical results and vibration technique can detect the inception of cavitation within a pump earlier than the acoustic technique. The results also revealed that, the combined use of these techniques (numerical and experimental) could increase the reliability. The combined method can be a considered to be a robust method, which can provide detailed information about the performance of the pump and detection/diagnosis of cavitation within a centrifugal pump. Hence, this will assist in prolonging the life of the pump and protect the system from emergency shutdown