The Experts below are selected from a list of 69 Experts worldwide ranked by ideXlab platform

H. W. Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Contact Analysis of Impeller-Shaft assembly and Reasonably Designing the Amount Interference of Turbocompressors
    III European Conference on Computational Mechanics, 2006
    Co-Authors: Ai-hua Liao, H. W. Zhang
    Abstract:

    The interference fit between Impeller and Shaft assembly is one of the most important factors influencing the performance of the turbo unit in the design of turbocompressors. The assembly creates a complicated frictional contact problem the interface of the mating parts when the rotational speed is high. Therefore, stress analysis and suitable amount of interference need to be considered in the structural design. A locomotive-type turbocompressor with 24 blades is used for the present analysis. The FE parametric quadratic programming (PQP) method which was developed based on the parametric variational principle (PVP) is used for the analysis of the stress distribution of 3-D frictional contact problem of Impeller-Shaft sleeve-Shaft, makes it possible to precisely simulate complicated geometrical shapes of Impeller and considerably enhances accuracy in computation. The advantages of the parametric programming method as compared with the conventional ones are that the penalty factors can be cancelled and the solutions can be obtained directly without tedious iterative procedures such as general incremental iterative method[1]. The effects of fit tolerance and rotational speed, the displacement and the contact stress on the interference-fitting surfaces are discussed in detail in this paper. A range of friction coefficients in the Impeller-Shaft sleeve and Shaft sleeve-Shaft contact interfaces is investigated in order to represent the mechanical behaviors of the structure due to the change of the interface characteristic. To decrease the difficulty of the assembling process and make sure the safety of the working state, the suitable amount of the interference is studied so that the interface can have adequate contact pressure under full load. It is found that nonuniform initial interference value in the structural design would avoid relative displacement generated and ensure uniformity of the contact stress. To assure quality of press-fitting, the amount of interference between the Shaft sleeve and Shaft by press-fitting should be controlled strictly to avoid the rapid increase of the contact stress. The study provides an effective approach which achieves more reliable interference-fitted connections and more precise assembly accuracy with lower manufacturing cost in the structural design.

Ai-hua Liao - One of the best experts on this subject based on the ideXlab platform.

  • Elastoplastic Frictional Contact Study on Interference Fits of Compressor
    2016
    Co-Authors: Ai-hua Liao
    Abstract:

    Abstract. The Impeller mounted onto the compressor Shaft assembly via interference fit is one of the key components of a centrifugal compressor stage. A suitable fit tolerance needs to be considered in the structural design. A locomotive-type turbocharger compressor with 24 blades under combined centrifugal and interference-fit loading was considered in the numerical analysis. The FE parametric quadratic programming (PQP) method which was developed based on the parametric variational principle (PVP) was used for the analysis of stress distribution of 3D elastoplastic frictional contact of Impeller-Shaft sleeve-Shaft. The solution of elastoplastic frictional contact problems belongs to the unspecified boundary problems where the interaction between two kinds of nonlinearities should occur. The effect of fit tolerance, rotational speed and the contact stress distribution on the contact stress was discussed in detail in the numerical computation. The study play a referenced role in deciding the proper fit tolerance and improving design and manufacturing technology of compressor Impellers

  • Contact Analysis of Impeller-Shaft assembly and Reasonably Designing the Amount Interference of Turbocompressors
    III European Conference on Computational Mechanics, 2006
    Co-Authors: Ai-hua Liao, H. W. Zhang
    Abstract:

    The interference fit between Impeller and Shaft assembly is one of the most important factors influencing the performance of the turbo unit in the design of turbocompressors. The assembly creates a complicated frictional contact problem the interface of the mating parts when the rotational speed is high. Therefore, stress analysis and suitable amount of interference need to be considered in the structural design. A locomotive-type turbocompressor with 24 blades is used for the present analysis. The FE parametric quadratic programming (PQP) method which was developed based on the parametric variational principle (PVP) is used for the analysis of the stress distribution of 3-D frictional contact problem of Impeller-Shaft sleeve-Shaft, makes it possible to precisely simulate complicated geometrical shapes of Impeller and considerably enhances accuracy in computation. The advantages of the parametric programming method as compared with the conventional ones are that the penalty factors can be cancelled and the solutions can be obtained directly without tedious iterative procedures such as general incremental iterative method[1]. The effects of fit tolerance and rotational speed, the displacement and the contact stress on the interference-fitting surfaces are discussed in detail in this paper. A range of friction coefficients in the Impeller-Shaft sleeve and Shaft sleeve-Shaft contact interfaces is investigated in order to represent the mechanical behaviors of the structure due to the change of the interface characteristic. To decrease the difficulty of the assembling process and make sure the safety of the working state, the suitable amount of the interference is studied so that the interface can have adequate contact pressure under full load. It is found that nonuniform initial interference value in the structural design would avoid relative displacement generated and ensure uniformity of the contact stress. To assure quality of press-fitting, the amount of interference between the Shaft sleeve and Shaft by press-fitting should be controlled strictly to avoid the rapid increase of the contact stress. The study provides an effective approach which achieves more reliable interference-fitted connections and more precise assembly accuracy with lower manufacturing cost in the structural design.

Yoshinori Kawase - One of the best experts on this subject based on the ideXlab platform.

  • power consumption and solid suspension performance of large scale Impellers in gas liquid solid three phase stirred tank reactors
    Chemical Engineering Journal, 2004
    Co-Authors: N. Dohi, Takanori Takahashi, K Minekawa, Yoshinori Kawase
    Abstract:

    Abstract An experimental investigation into power consumption and solid suspension performance of large-scale Impellers was carried out under turbulent conditions. Two types of large-scale Impellers, i.e. Maxblend and Fullzone Impellers, were employed. For reference, a triple-Impeller system, i.e. two four-pitched blade downflow disk turbines (DTs) at middle and upper positions and one Pfaudler type Impeller at lower position, was also used. The power consumption and the minimum Impeller speeds for off-bottom solid suspension and minimum Impeller speeds for ultimately homogeneous solid suspension were measured in unaerated and aerated systems. At a given rotational speed, the power consumption of the Maxblend Impeller was roughly half of that of the Fullzone Impeller. The decrease in power consumption due to aeration for large-scale Impellers was smaller as compared with that for the triple-Impeller system. The proposed correlation for power consumption of large-scale Impellers in three-phase systems fit the experimental data reasonably well. Interesting and unexpected solid movements caused by the large-scale Impellers in the vessels having oval bottom were observed. Since the large-scale Impellers create strong axial liquid recirculation flowing downward near the Impeller Shaft and upward near the wall, usually particles are expected to move outward on the tank bottom. On the contrary, however, solid particles near the bottom moved to the center of the base from the side along the oval tank bottom. The large-scale Impellers were found to be more efficient for solid suspension than the triple-Impeller system. The Maxblend Impeller provided the best solid suspension ability among the three Impellers used in this work. We proposed a correlation for power consumption of large-scale Impellers in gas–liquid–solid three-phase systems. Empirical correlations were also proposed for the minimum Impeller speeds for off-bottom solid suspension, minimum Impeller speeds for ultimately homogeneous solid suspension and power consumption at the minimum Impeller speeds for ultimately homogeneous solid suspension.

Jicheng He - One of the best experts on this subject based on the ideXlab platform.

  • intensification of bubble disintegration and dispersion by mechanical stirring in gas injection refining
    Tetsu To Hagane-journal of The Iron and Steel Institute of Japan, 2010
    Co-Authors: Masamichi Sano, Tingan Zhang, Qiang Wang, Jicheng He
    Abstract:

    Water model experiments were performed for developing highly efficient gas injection refining processes. Mechanical stirring was applied to disintegrate the injected bubbles and to disperse them widely in the bath. The bubble disintegration and dispersion were investigated by changing rotation mode (direction of rotation), rotation speed and blade size of the Impeller, and gas flow rate. Forward rotation of the Impeller induced a stable tangential flow and could not disperse bubbles in the bath due to formation of a vortex around the Impeller Shaft. The tangential flow was suppressed by forward-interrupt rotation, which could reduce the vortex formation to some degree. However, the forward-interrupt rotation could not disperse the bubbles widely in the bath. Forward–reverse rotation could prevent the vortex formation completely and create a turbulent and strong shear stress field, which intensified the bubble disintegration and dispersion in the bath. Higher Impeller rotation speed and larger blade length in the forward–reverse rotation could enhance the bubble disintegration more intensely, and make the dispersed bubbles smaller and the bubble dispersion zone wider. The bubble size tended to be larger at higher gas flow rates. However, its dependence on the gas flow rate became smaller at higher Impeller rotation speed.

  • intensification of bubble disintegration and dispersion by mechanical stirring in gas injection refining
    Isij International, 2009
    Co-Authors: Masamichi Sano, Tingan Zhang, Qiang Wang, Jicheng He
    Abstract:

    Water model experiments were performed for establishing highly efficient gas injection refining processes. Mechanical stirring was applied to disintegrate the injected bubbles and to disperse them widely in the bath. The bubble disintegration and dispersion were investigated by changing rotation mode (direction of rotation), rotation speed, blade size of the Impeller and gas flow rate. Forward rotation of the Impeller induced a stable tangential flow and could not disperse bubbles in the bath due to formation of a vortex around the Impeller Shaft. The tangential flow could be suppressed by forward–interrupt rotation, which could reduce the vortex formation to some degree. However, forward–interrupt rotation could not disperse the bubbles widely in the bath. Forward–reverse rotation could prevent the vortex formation completely and create a strong shear stress field, which intensified the bubble disintegration and dispersion in the bath. Higher Impeller rotation speed and larger blade length in forward–reverse rotation could enhance the bubble disintegration and make the dispersed bubbles smaller. The bubble dispersion zone became wider with larger blade length. The bubble size tended to be larger at higher gas flow rates. However, its dependence on the gas flow rate became smaller at higher Impeller rotation speed.

Masamichi Sano - One of the best experts on this subject based on the ideXlab platform.

  • mechanical stirring for highly efficient gas injection refining
    Transactions of Nonferrous Metals Society of China, 2011
    Co-Authors: Yan Liu, Tingan Zhang, Masamichi Sano, Qiang Wang, Xiaodong Ren, H E Jicheng
    Abstract:

    Abstract In gas injection refining processes, wide dispersion of small bubbles in the bath is indispensable for high refining efficiency. Eccentric mechanical stirring with unidirectional Impeller rotation was tested using a water model for pursuing better bubble disintegration and dispersion. Effects of various factors on bubble disintegration and dispersion were investigated. These factors were stirring mode, eccentricity and rotation speed, nozzle structure, nozzle immersion depth, and gas flow rate. Gas injection from a nozzle at the end of the Impeller Shaft and from an immersed lance was studied. Under eccentric stirring, a vortex was formed away from the Shaft. Small bubbles were produced in the strong turbulence or high shear stress field near the rotating Impeller and moved in the direction to the vortex keeping up with the macroscopic flow induced by the mechanical stirring. Thus small bubbles could disperse widely in the bath under eccentric stirring with unidirectional rotation.

  • intensification of bubble disintegration and dispersion by mechanical stirring in gas injection refining
    Tetsu To Hagane-journal of The Iron and Steel Institute of Japan, 2010
    Co-Authors: Masamichi Sano, Tingan Zhang, Qiang Wang, Jicheng He
    Abstract:

    Water model experiments were performed for developing highly efficient gas injection refining processes. Mechanical stirring was applied to disintegrate the injected bubbles and to disperse them widely in the bath. The bubble disintegration and dispersion were investigated by changing rotation mode (direction of rotation), rotation speed and blade size of the Impeller, and gas flow rate. Forward rotation of the Impeller induced a stable tangential flow and could not disperse bubbles in the bath due to formation of a vortex around the Impeller Shaft. The tangential flow was suppressed by forward-interrupt rotation, which could reduce the vortex formation to some degree. However, the forward-interrupt rotation could not disperse the bubbles widely in the bath. Forward–reverse rotation could prevent the vortex formation completely and create a turbulent and strong shear stress field, which intensified the bubble disintegration and dispersion in the bath. Higher Impeller rotation speed and larger blade length in the forward–reverse rotation could enhance the bubble disintegration more intensely, and make the dispersed bubbles smaller and the bubble dispersion zone wider. The bubble size tended to be larger at higher gas flow rates. However, its dependence on the gas flow rate became smaller at higher Impeller rotation speed.

  • intensification of bubble disintegration and dispersion by mechanical stirring in gas injection refining
    Isij International, 2009
    Co-Authors: Masamichi Sano, Tingan Zhang, Qiang Wang, Jicheng He
    Abstract:

    Water model experiments were performed for establishing highly efficient gas injection refining processes. Mechanical stirring was applied to disintegrate the injected bubbles and to disperse them widely in the bath. The bubble disintegration and dispersion were investigated by changing rotation mode (direction of rotation), rotation speed, blade size of the Impeller and gas flow rate. Forward rotation of the Impeller induced a stable tangential flow and could not disperse bubbles in the bath due to formation of a vortex around the Impeller Shaft. The tangential flow could be suppressed by forward–interrupt rotation, which could reduce the vortex formation to some degree. However, forward–interrupt rotation could not disperse the bubbles widely in the bath. Forward–reverse rotation could prevent the vortex formation completely and create a strong shear stress field, which intensified the bubble disintegration and dispersion in the bath. Higher Impeller rotation speed and larger blade length in forward–reverse rotation could enhance the bubble disintegration and make the dispersed bubbles smaller. The bubble dispersion zone became wider with larger blade length. The bubble size tended to be larger at higher gas flow rates. However, its dependence on the gas flow rate became smaller at higher Impeller rotation speed.