As an essential tool for measuring flow field, pneumatic probes have gained a wide range of applications. In order to obtain the flow field parameters accurately, it is also crucial to study the deformation of the pneumatic probe structure in flow field. In this paper, the deformation of the conical probe is numerically simulated under the condition of steady incoming flow in the transonic flow field. The fluid-structure interaction and modal analysis methods are used to obtain the deformation and vibration frequency of the probe. The results show that the vibration of the probe is underdamped under the action of two-way fluid-structure interaction, and the total deformation decays exponentially, and the total deformation after stabilization is the same as the result of one-way fluid-structure interaction. For the same material probe, the total deformation changes with time in the same dimensionless expression, and the vibration frequency as well as damping factor do not change due to the variation of flow field. The accuracy of the dimensionless expressions was verified by different incoming flow conditions and the probe material. For the cases studied in this paper, the maximum total deformation, vibration frequency and damping factor of the probe in the flow field can be obtained by using one-way fluid-structure interaction, modal analysis and two-way fluid-structure interaction with a small number of cycles, respectively, so that the total deformation of the probe in the flow field can be predicted over time. The method obtained in this paper can significantly reduce the calculation time for obtaining the probe deformation data in the flow field and improve the work efficiency, which can provide a reference for the design, calibration and application of probes in engineering applications.

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CFD is used extensively to predict the performance of pumps and has proven to be a reliable tool for low viscosity fluids. Pump performance for high viscous operation is generally predicted from its water performance using empirical formulas, for example from the Hydraulic Institute standard ANSI/HI 9.6.7. However, the domain of application of these formulas is limited to certain pump sizes and configurations. The use of CFD as a tool for this task seems obvious, but not many studies on this topic have been presented so far. Several aspects of such a CFD calculation are not trivial, such as the effect of the viscous heating or the fact that the flow regime will not be fully turbulent in a large portion of the pump domain depending on the operating conditions and the viscosity. To provide some insight into the requirements for such CFD simulations, investigations of a single stage, double suction volute pump operating with water and oil were carried out and compared to measurement data covering a broad operating range. The results show that both the SST and intermittency turbulence models can predict the pump performance for high viscosity fluids well, despite local differences in flow regime prediction.

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In this study, we created an optimization design method for a rotor of propeller-type wind turbine that combined design of experiments, response surface method, and optimization method with the blade element momentum theory. This design method was applied to a small propeller-type wind turbine. We then examined the performance of an obtained rotor using a three-dimensional computational fluid dynamics analysis and a wind tunnel experiment and examined the relationship between local torque and pressure distribution on the blade surface to investigate the mechanism to improve power output. Our findings showed that the experimental value of power coefficient of optimized rotor designed with our design method was approximately 6.9% higher than that of an original rotor designed with the blade element momentum theory only. This was because the optimized rotor had similar pressure difference between the pressure surface and the suction surface to that of the original rotor as the separation at the leading edge side were decreased on the tip side, and because its local torque increased as the pressure difference increased due to a longer chord length. Thus, the effectiveness of our design method was demonstrated.

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To provide stable operation over a wide flow range, centrifugal pumps should have high pump efficiency at a low flow rates and high total head. A new impeller with radial and annular flow channels that has higher pumping performance than conventional design impellers with the same specific speed and flow rate at a low specific speed was proposed. however, a high unsteady flow was observed inside the pump. In this study, to predict performance and clarify internal flow accurately, unsteady CFD was used to investigate pump performance and internal flow, including different hydraulic losses when the impeller rotates once rotation. The results show that pump performance can be estimated more accurately using unsteady CFD than using steady CFD. Moreover, the constant drop in total head with flow rate is owing to the hydraulic losses in the impeller, which exclude friction, growing in proportion to flow rate.

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Due to its high porosity as well as a high specific surface area, the use of open cell metallic foam in heat transfer applications has received increasing interest. In present study, the dynamic and thermal performance of heat exchanger composed of copper foam incorporated in a fan coil was numerically analyzed. Darcy-Brinkman-Forchheimer model was used to represent the momentum equation inside the metallic foam (a porous medium). A local thermal equilibrium was used to solve the energy equation through the porous medium. Different porosity values were taken during the study, ranging from 0.88 to 0.98, while the velocity of inlet air of the heat exchanger ranged from 1 m/s to 10 m/s. The objective of current study is to compare the thermal and dynamic performance of the heat exchanger affected by several variables such as heat transfer coefficient, friction factor, pressure drop, Colburn factor, and area goodness factor. The results showed that increasing the air inlet velocity will increase the heat transfer coefficient, but on the other hand, increasing the velocity ten times will rise pressure drop from 19.032 Pa to 335.76 Pa. Also, the area goodness factor value will decrease with increasing inlet velocity. Finally, we found that increasing in medium porosity will reduce heat transfer coefficient but increase pressure drop.

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Cavitation in the pump induces vibration and noise, which leads to the degradation of pump performance and damage to the impeller. Therefore, it is of great significance to accurately identify the cavitation state of the centrifugal pump. To determine the cavitation state using the vibration characteristic frequency of the centrifugal pump, it is necessary to accurately identify the characteristic frequency due to the noise's effect. Therefore, a cavitation fault diagnosis method of centrifugal pump based on a cohesive hierarchy algorithm was proposed. Firstly, Singular Value Decomposition (SVD) is used to de-noise the vibration signal. Then the root means square of the vibration signal after de-noising is obtained as the eigenvalue of the vibration signal. Secondly, the hierarchical clustering algorithm is used to classify the vibration eigenvalues and accurately identify the non-cavitation and cavitation states of centrifugal pumps. Finally, through experimental tests, the method can effectively and quickly identify the cavitation state of the centrifugal pump, with an accuracy of 95%. The study provides a new way for rapidly diagnosing centrifugal pump cavitation.

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The existing methods for studying the dynamics, thermodynamics and deformation characteristics of screw pumps do not consider the coupling effect of multi field interaction, which deviates from the actual working conditions. Based on SolidWorks and ANSYS software, a three-dimensional finite element model of a lead of conventional single screw pump is established in this paper. The influence of different gas(GVF) volume fraction on the temperature, pressure, deformation, leakage and volumetric efficiency of screw pump was studied by using the fluid-thermal-solid coupling method. The numerical simulation results of volumetric efficiency changing with the inlet and outlet pressure difference under pure liquid condition were verified by the published literature experimental data, and the optimal installation interference value was proposed. The results show that the GVF has an important influence on the comprehensive deformation of the rotor and pump bushing and the volumetric efficiency of the pump; the comprehensive deformation value of the rotor increases gradually from the inlet to the outlet, and increases gradually with the increase of the GVF; with the increase of GVF, the comprehensive deformation value of stator first decreases gradually, and then increases sharply; with the increase of GVF, the leakage first decreases slowly, then increases rapidly, and the volumetric efficiency first increases slowly, then decreases rapidly; the numerical simulation results are in good agreement with the experimental values, and the average deviation is less than 7%.

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In this study, a multi-objective optimization design method, combining a design of experiments, single-phase flow analysis, response surface method and a multi-objective optimization method was developed to optimize the collection device shape of an axial flow hydraulic turbine with a collection device to achieve high power and low axial thrust. In addition, the effectiveness of this design method was validated through verification experiments in an open channel with shallow water depth and multiphase flow analysis considering a free surface, and the differences from the single-phase flow analysis results were also discussed. As a result, the optimized collection device obtained by this design method showed the same axial thrust coefficient and improved power coefficient compared with the original collection device in the single-phase flow analysis. In the open channel, the power coefficient of the optimized collection device was significantly higher than that of the original collection device, but unlike the results of the single-phase flow analysis, the axial thrust coefficient of the diffuser was significantly increased, resulting in a significant increase in total axial thrust coefficient.

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This study proposes a new unified performance model for the S-shaped characteristics of pump–turbines considering reverse flow. The turbine and reverse pump characteristic equations were unified using a sigmoid function considering the reverse flow. In the analysis, the torque coefficient is larger for small guide vane angles than for large guide vane angles due to an increase in the turbine Euler head. In the turbine mode, the runner shock loss and the circumferential discharge loss are directly proportional to the shock dynamic pressure and the circumferential dynamic pressure in the discharge section, respectively. In the reverse pump mode, the guide vane shock and friction losses are directly proportional to the shock dynamic pressure and the absolute dynamic pressure, respectively. The S-shaped characteristics of pump–turbines can be completely simulated using the proposed theoretical model.

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The present work propose a momentum exchange theory with new generalized pressure and leakage flow loss models for designing and predicting performance of open channel type regenerative blower. The pressure loss and leakage flow models are composed of related fluid mechanics correlation equations and generalized to consider the influence of the design variables and operating conditions of the blower. The prediction accuracy is verified by applying this performance prediction method to eight open channel type blower models, and the prediction and test results are very consistent within the entire flow capacity range.

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