NUMERICAL SIMULATION AND PIV MEASUREMENT ON THE FLOW FIELD WITHIN JET PUMPS

LONG XINPING,ZHU JINMU,HE PEIJIE,LIANG AIGUO 한국수자원학회 2005 한국수자원학회 학술대회 Vol.2005 No.1

Influence of nozzle exit tip thickness on the performance and flow field of jet pump

Xinping LONG,Ning HAN,Qian CHEN 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.10

The influence of exit tip thickness of nozzle δ e on the flow field and performance of a jet pump was studied numerically in this paper. It is found that δ e has influence on the distribution of turbulence kinetic energy k. If δ e is ignored, k takes the highest value but dissipates rapidly than that of nozzle with a certain tip thickness. δ e also affect apparently the development of tip vortex, which will occur near the exit tip of nozzle. The bigger the δ e is, the larger the vortex is. The tip vortex develops with the increase of flow rate ratio q. When q=1 and δ e=0.6~0.8mm, a small vortex will be found downstream the tip vortex. And a concomitant vortex happens down the tip vortex in the case of q=1 and δ e=0.8mm. As q increases to 2, the downstream small vortex disappears and the concomitant vortex becomes bigger. It is also found that the tip vortex might interact with the possible backflow that formed in the throat tube and parts of suction chamber. The center of backflow was affect evidently by δ e. With the increase of δ e, the center of backflow under the same q will go downstream. When δ e=0.4mm, the center of backflow goes farthest. Then, as the further increase of δ e, the center of backflow will go back some distance. Although, δ e has relatively great influence on the flow field within the jet pump, it exerts only a little impact on the performance of jet pump. When δ e=0.2~0.6mm, the jet pump possess better performance. In most case, it is reasonable to ignore the nozzle exit tip thickness in performance prediction for the purpose of simplicity.

Research on a new type of squirt gun for cleaning

Jinmu ZHU,Xinping LONG,Weifeng WU,Hao YAO 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.10

A new type of squirt gun, which is similar to a jet pump and can better induce formation of cavitating water jet, is presented. The scheme of design of this new squirt gun is discussed. An investigation of effect of different area ratio, length of throat pipe, standoff distance, nozzle type, and suction air amount on decontamination ability was made by experiments. This new squirt gun is experimentally compared with conventional one. Test data indicate that under the same operating condition the new type of squirt gun have the advantages of better decontamination ability, lower energy consumption and less water consuming over conventional one. The optimum operating parameters of this new device are put forward on the basis of test results.

Application of Constant Rate of Velocity or Pressure Change Method to Improve Annular Jet Pump Performance

Yang, Xuelong,Long, Xinping,Kang, Yong,Xiao, Longzhou Korean Society for Fluid machinery 2013 International journal of fluid machinery and syste Vol.6 No.3

To improve annular jet pump (AJP) performance, new ways named constant rate of velocity/pressure change method (CRVC/CRPC) were adopted to design its diffuser. The design formulas were derived according to the assumption of linear velocity/pressure variation in the diffuser. Based on the two-dimensional numerical simulations, the effect of the diffuser profile and the included angle on the pump performance and the internal flow details has been analyzed. The predicted results of the RNG k-epsilon turbulence model show a better agreement with the experiment data than that of the standard and the realizable k-epsilon turbulence models. The AJP with the CRPC diffuser produces a linear pressure increase in the CRPC diffuser as expected. The AJP with CRPC/CRVC diffuser has better performance when the diffuser included angle is greater or the diffuser length is shorter. Therefore, the AJP with CRPC/CRVC diffuser is suitable for applications requiring space limitation and weight restriction.

Numerical investigation on the recirculation in annular jet pumps

Longzhou Xiao,Xinping LONG,Xiaohong Li,Qinglong Zeng,Xuelong Yang 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.6

The flow within the annular jet pump (AJP), in some degree, resembles the annular wall jet developing in a pipe with great axial pressure gradient. In some working conditions, there exists the backflow near the centerline. However this differs from the case in a center jet pump (CJP) that the recirculation emerges near the inner wall of the throat. The recirculation in AJP affects a lot to its performance, especially when AJP is utilized to convey something alive, such as fish. This paper aims to numerically study the impact of two parameters, the flow ratio M and the area ratio A, on the location, size and formation of the recirculation in AJP. After being validated by the experimental results, the RNG k-ε turbulent model was adopted. It is found that: (1) As M increases, the width and height of the recirculation in AJP decreases, and the separation point of the recirculation shifts gradually far away from the nozzle exit while the reattachment point slightly moves; (2) As A becomes larger, the width and height of the recirculation enlarged, with M keeping constant; (3) For AJP with constant A, the recirculation emerges when M declines to a critical value, and the value varies linearly with A; (4) The Craya-Curtet number Ct and the momentum ratio J, which take A and M into whole consideration, are also feasible in describing the disappearance of the recirculation. However the critical value of Ct and J are different from that discovered in CJP. The critical Ct increases with decreasing A and the critical momentum ratio Jc experiences a linear relationship with A.

Application of Constant Rate of Velocity or Pressure Change Method to Improve Annular Jet Pump Performance

Xuelong Yang,Xinping LONG,Yong Kang,Longzhou Xiao 한국유체기계학회 2013 International journal of fluid machinery and syste Vol.6 No.3

To improve annular jet pump (AJP) performance, new ways named constant rate of velocity/pressure change method (CRVC/CRPC) were adopted to design its diffuser. The design formulas were derived according to the assumption of linear velocity/pressure variation in the diffuser. Based on the two-dimensional numerical simulations, the effect of the diffuser profile and the included angle on the pump performance and the internal flow details has been analyzed. The predicted results of the RNG k-epsilon turbulence model show a better agreement with the experiment data than that of the standard and the realizable k-epsilon turbulence models. The AJP with the CRPC diffuser produces a linear pressure increase in the CRPC diffuser as expected. The AJP with CRPC/CRVC diffuser has better performance when the diffuser included angle is greater or the diffuser length is shorter. Therefore, the AJP with CRPC/CRVC diffuser is suitable for applications requiring space limitation and weight restriction.

Implementation of design of experiment for structural optimization of annular jet pumps

Qiao Lyu,Zhihuai Xiao,Qinlong Zeng,Longzhou Xiao,Xinping LONG 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.2

The DOE (Design of experiments) method together with CFD (Computational fluid dynamics) was applied to optimize structural combination of the Annular jet pumps (AJPs). An AJP with an area ratio of 1.75 was selected as the simulation prototype and the numerical results were validated by experiments. According to the DOE method, four impact factors were selected for simulation. The results showed that two-factor’s reciprocal action is more applicable than that of single factor on the AJP’s performance, especially the two groups ,α*l t and l t *β, respectively. The structure of AJPs with different area ratios ranging from 1.5 to 40 were optimized by the DOE method. The corresponding optimum structural parameters and performance curves were plotted to acquire the performance envelope lines, the efficiency envelope line and the peak efficiency lines, which are useful for AJP’s structure design and obtaining its operation condition.

Mechanism and Experimental Investigation of Ultra High Pressure Water Jet on Rubber Cutting

Yi Hu,Yong Kang,Xiao-Chuan Wang,Xiao-Hong Li,Xinping LONG,Guang-Yao Zhai,Man Huang 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.

The recycle and reuse of rubber materials has become a global environment problem with the fast increasing amount of waste rubber. Compared to traditional recycle methods, ultra high pressure water jet, as a fast developing tool of cool cutting, can be used inrecycling rubber materials without damaging the internal organization structure of materials. This paper investigates ultra highpressure jet cutting rubber in mechanism and experiment. Different from metallic materials and brittle materials, rubber materialsare cut by the force of shear and tensile under the impinging of ultra high pressure water jet and the erosion of high speed waterflow with rubber powder. The overall structure of kerf is Y shape. The upper section of Y shape is caused by shear, the middle sectionis resulted from both shear and tensile, and the bottom section is a result of the erosion and the tensile. The results of experimentshow: (1) a significant linear correlation between cutting depth and pump pressure;(2) 2.0 mm/s is the optimal transverse velocityunder the current experiment condition;(3) the cutting depth has a decreasing tendency with the stand-off distance increased. It canbe concluded from orthogonal analysis that pump pressure has a signification effect on cutting depth, nozzle transverse velocity isnot remarkable, and the effect of stand-off distance is not obvious.