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Wang J.,Wuhan University | Wang J.,Key Laboratory of Hubei Province for Waterjet Theory and New Technology | Li J.-Y.,Wuhan University | Li J.-Y.,Key Laboratory of Hubei Province for Waterjet Theory and New Technology | Guan K.,Wuhan University
Kung Cheng Je Wu Li Hsueh Pao/Journal of Engineering Thermophysics | Year: 2014

Design of experiment and data analysis of self-excited pulse jet have been done in the paper. The relationship between nozzle structure and operating pressure has been studied based on the response function of self-excited frequencies, amplitude and hitting force. The periodic cavitation in the chamber and its effect on the self-excited pulse has been revealed according to the analysis of self-excited frequency and amplitude. Then the generative mechanism of self-excited pulse was revealed. The empirical formula of the hitting force on the various parameters has been concluded based on the results of the experiment. The relationship between the typical size range of the pulse nozzle, the self-excited frequency and hitting force for various industrial applications have been promoted in the end. The experimental data have been provided to frequency modulation for industrial design. Source


Wang J.,Wuhan University | Wang J.,Key Laboratory of Hubei Province for Waterjet Theory and New Technology | Li J.-Y.,Wuhan University | Li J.-Y.,Key Laboratory of Hubei Province for Waterjet Theory and New Technology | And 2 more authors.
Kung Cheng Je Wu Li Hsueh Pao/Journal of Engineering Thermophysics | Year: 2013

The sensitive multi-frequency performance characteristic of the self-excited jet has been studied by experiment. Experiment design and experiment about the structure of nozzles and cavity and operating parameters have been done to research the self-excited effects. Fractional factorial design theory is used to the data analysis and draws a conclusion that the operating pressure, the diameters of the inlet and outlet, the length of the cavity have a significant impact on the self-excited effects. Moreover, interaction effects exist among the operating pressure, the inlet diameter, the outlet diameter and the length of the cavity. Under test conditions, the hitting force of the self-excited pulse jet reaches 1.3 times of that of the continuous jet. Optimal value exists in the dependence of the hitting force on the outlet diameter. At last, frequency analysis is performed by Fast Fourier Transform Algorithm (FFT). Source


Yang X.,Hubei Engineering University | Yang X.,Key Laboratory of Hubei Province for Waterjet Theory and New Technology | Long X.,Hubei Engineering University | Long X.,Key Laboratory of Hubei Province for Waterjet Theory and New Technology | And 4 more authors.
Paiguan Jixie Gongcheng Xuebao/Journal of Drainage and Irrigation Machinery Engineering | Year: 2013

To study the effect of different turbulence models and related wall boundary treatment methods on the simulation of the performance and internal flow field of a jet pump, and to find their good combination, six turbulence models (namely, three k-ε models, standard and SST k-ω models and Reynolds stress models) and two wall treatment methods (standard wall functions and enhanced wall treatment) were combined in different ways. Standard wall functions and enhanced wall treatment were respectively applied to three k-ε models and RSM model. Both k-ω models were used as low-Reynolds-number models without applying any wall treatment methods. Ten combinations were thus obtained. The data of the performance and the static wall pressure distribution of a jet pump were employed as the criteria to validate the simulation results. The results show that all the ten combinations agree well with the experiment data when the volumetric flow ratio is relatively low, and all simulation errors of the ten combinations are greater than 10% when working at relatively high flow ratio. After adjusting constants of the turbulent model, for some combinations, the difference between the errors of the predicted results and the experiment data were lowered to be less than 5%. The model constant C2ε has a greater influence than σε on the calculation; and the maximum turbulence energy decreases as C2ε or σε decreases, but the distribution region of turbulence energy expands correspondingly. Source


Xu M.,Wuhan University | Xu M.,Key Laboratory of Hubei Province for Waterjet Theory and New Technology | Long X.,Wuhan University | Long X.,Key Laboratory of Hubei Province for Waterjet Theory and New Technology | And 8 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2016

Potatoes are the fourth global economic crop following wheat, rice and maize. With the increase of potato production, potato transportation has become an important problem restricting the current potato industry. The traditional method usually uses belt conveyors to transport the potato. However, belt conveyors are not able to convey potatoes vertically and some of potatoes are mechanically damaged during the transportation process, which seriously limits the development of potato transportation. In present paper, annular jet pumps (AJPs) were proposed and used for the transportation of potatoes because of their broad flow passages without any rotating part, which reduced the possibility of potato damage. This jet potato pump (JPP) had high potential for the transportation of potatoes due to its simple structure and lesser tendency towards mechanical damage. Considering the characteristics of the potato transportation, a conical net tube was used to centralize potatoes with extremely low possibility of mechanical damage, and the lift height was used to control the outlet pressure instead of the outlet tube valve, which avoided potential mechanical damage on potatoes. Based on the experimental method, we demonstrated the impacts of flow ratio, area ratio as well as the lift height of JPP on the capacity in potato transportation. Meanwhile, according to potato mass changes after transportation, we also investigated different types of mechanical damage and discussed the corresponding operation conditions. The results showed that the maximum capacity of potato transportation reached 1667.46 kg/h for this JPP in the experiment, and the corresponding hydraulic power and energy consumption per unit mass were 3.93 kW and 2.36 kW•h/t respectively. The transportation capacity and hydraulic power increased with the increase of flow ratio under the same area ratio and lift height, and the energy consumption per unit mass changed little under small flow ratio but increased sharply under big flow ratio; the transportation capacity dropped with the rise of area ratio under the same secondary flow and lift height, which was relevant to JPP external characteristics; the transportation capacity decreased, yet the energy consumption per unit mass of potato increased with the increase of lift height under the same primary flow and area ratio. In most operation conditions, surrounded by water, potatoes were free from mechanical injury presented as few mass loss or even mass increase due to water absorption. However, a few potatoes were found damaged in the small flow ratio condition characterized by recirculation in nozzle exit and suction chamber. According to the mass loss rate, the damage of potatoes could be classified into 2 types, i.e. skin damage (mass loss less than 1.00%) and local damage (mass loss more than 1.00%). These corresponding mechanical damages were mainly caused by potato's collisions with other potatoes or the nozzle in the suction chamber under small flow ratio. Therefore, considering the transportation capacity and damage rate, the optimum operation condition (area ratio of 1.75, flow ratio of 0.49 and lift height of 1.40 m) was recommended in this research. Consequently, the main contribution of our work is to demonstrate the influence of flow ratio, area ratio and lift height on the transportation of potatoes and to discuss the potential damage risks caused by operation conditions for potatoes in the JPP. More importantly, the present paper proves the potential of JPP for potato transportation and provides the references for the optimization of JPP, which aims to minimize the potato damage rate and improve the transportation capacity of potatoes. © 2016, Chinese Society of Agricultural Engineering. All right reserved. Source

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