The Experts below are selected from a list of 4056 Experts worldwide ranked by ideXlab platform
Magnus Genrup - One of the best experts on this subject based on the ideXlab platform.
-
Numerical Investigation of the Effect of Different Back Sweep Angle and Exducer Width on the Impeller Outlet Flow Pattern of a Centrifugal Compressor With Vaneless Diffuser
Journal of Turbomachinery, 2007Co-Authors: Andrea Hildebrandt, Magnus GenrupAbstract:This paper presents a numerical investigation of the effect of different back sweep angles and exducer widths on the steady-state impeller Outlet Flow pattern of a centrifugal compressor with a vaneless diffuser. The investigations have been performed with commercial CFD and in-house programmed 1-D codes. CFD calculations aim to investigate how Flow pattern from the impeller is quantitatively influenced by compressor geometry parameters; thereby, the location of wake and its magnitude (Flow angle and relative velocity magnitude) are analyzed. Results show that the increased back sweep impeller provides a more uniform Flow pattern in terms of velocity and Flow deviation angle distribution, and offers better potential for the diffusion process inside a vaneless (or vaned) diffuser. Secondary flux fraction and Flow deviation angle from CFD simulation are implemented into the 1-D two-zone program to improve 1-D prediction results.
-
Numerical Investigation of the Effect of Different Back Sweep Angle and Exducer Width on the Impeller Outlet Flow Pattern of a Centrifugal Compressor With Vaneless Diffuser
Journal of Turbomachinery, 2006Co-Authors: Andre Hildebrandt, Magnus GenrupAbstract:This paper presents a numerical investigation of the effect of different back sweep angles and exducer widths on the steady-state impeller Outlet Flow pattern of a centrifugal compressor with a vaneless diffuser. The investigations have been performed with commercial computational fluid dynamics (CFD) and in-house programmed one-dimensional (ID) codes. CFD calculations aim to investigate how Flow pattern from the impeller is quantitatively influenced by compressor geometry parameters; thereby, the location of wake and its magnitude (Flow angle and relative velocity magnitude) are analyzed. Results show that the increased back sweep impeller provides a more uniform Flow pattern in terms of velocity and Flow deviation angle distribution, and offers better potential for the diffusion process inside a vaneless (or vaned) diffuser Secondary flux fraction and Flow deviation angle from CFD simulation are implemented into the ID two-zone program to improve ID prediction results. (Less)
Y.-p. Tsia - One of the best experts on this subject based on the ideXlab platform.
-
Heat Transfer and Pressure Drop in Pin-Fin Trapezoidal Ducts
Journal of Turbomachinery, 1999Co-Authors: Jenn-jiang Hwang, D.-y. Lai, Y.-p. TsiaAbstract:Experiments are conducted to determine the log-mean averaged Nusselt number and overall pressure-drop coefficient in a pin-fin trapezoidal duct that models the cooling passages in modern gas turbine blades. The effects of pin arrangement (in-line and staggered), Flow Reynolds number (6,000 0.8, the log-mean averaged Nusselt number is nearly independent of the pin configuration. Moreover, the staggered pin array pays more pressure-drop penalty as compared with the in-line pin array in the straight-Outlet-Flow duct; however, in the lateral-Outlet-Flow duct, the in-line and staggered pin arrays yield almost the same overall pressure drop.
-
Heat Transfer and Pressure Drop in Pin-Fin Trapezoidal Ducts
Volume 4: Heat Transfer; Electric Power; Industrial and Cogeneration, 1998Co-Authors: Jenn-jiang Hwang, D.-y. Lia, Y.-p. TsiaAbstract:Experiments are conducted to determine the log-mean averaged Nusselt number and overall pressure-drop coefficient in a pin-fin trapezoidal duct that models the cooling passages in modem gas turbine blades. The effects of pin arrangement (in-line and staggered), Flow Reynolds number (6,000 ≦ Re ≦ 40,000) and ratio of lateral-to-total Flow rate (0 ≦ e ≦ 1.0) are examined. The results of smooth trapezoidal ducts without pin arrays are also obtained for comparison. It is found that, for the single-Outlet-Flow duct, the log-mean averaged Nusselt number in the pin-fin trapezoidal duct with lateral Outlet is insensitive to the pin arrangement, which is higher than that in straight-Outlet-Flow duct with the corresponding pin array. As for the trapezoidal ducts having both Outlets, the log-mean averaged Nusselt number has a local minimum value at about e = 0.3. After about e ≧ 0.8, the log-mean averaged Nusselt number is nearly independent on the pin configuration. Moreover, the staggered pin array pays more pressure-drop penalty as compared with the in-line pin array in the straight-Outlet-Flow duct: however, in the lateral-Outlet-Flow duct, the in-line and staggered pin arrays yield almost the same overall pressure drop.Copyright © 1998 by ASME
O. Espejo-alcaraz - One of the best experts on this subject based on the ideXlab platform.
-
Residence time distribution for unsteady-state systems
Chemical Engineering Science, 2000Co-Authors: J. Fernández-sempere, R. Font-montesinos, O. Espejo-alcarazAbstract:The concept of residence time distribution (RTD) can also be applied to incompressible fluids in closed-closed systems under nonsteady conditions, when the residence time distribution expressed as a function of a residence time, defined in this paper, is independent of the volume and/or the Flow rate. In this paper, an analysis of the hydrodynamics of the plug Flow reactor (PFR), the continuous stirred tank reactor (CSTR), the plug Flow reactor with axial dispersion (DFR) and a series of n-CSTR under unsteady-state conditions is made. A generalized residence time distribution is proposed for analyzing the behavior of the system. The proposed RTD is applied to the experimental data obtained when a tracer is introduced as a pulse in a sewage system. Three runs, with different Outlet Flow ranges, were carried out. By means of the generalized RTD, a disperse Flow reactor model for correlating the experimental data was proposed. In this way, the variation deduced in the tracer Outlet concentration can be explained, despite the fact that the Outlet Flow range is different from one run to another.
Yong-bin Lai - One of the best experts on this subject based on the ideXlab platform.
-
Numerical and experimental research on the Outlet Flow field for the air multiplier
Applied Thermal Engineering, 2016Co-Authors: Hai-shun Deng, Yong-bin LaiAbstract:Abstract The Outlet Flow field of the air multiplier was simulated by a RNG k – e model based on compressible fluid, and the simulated results were validated experimentally through a Constant Temperature Anemometer (CTA) hot-wire system and the ventilating multi-parameter testing instrument. The Flow characteristics and the reason for the increase of the output Flow rate relative to the turbine intake rate were revealed by investigating profiles of the time-averaged velocity and pressure. The results indicate that (1) the Flow parameter profiles in the Outlet Flow field are not uniform, and the entire time-averaged velocity field and pressure field in near field are basically axis symmetrical in the horizontal direction instead of in the vertical direction; (2) the entrainment and suction effects resulted from the “coronary zone” of the established Flow of high intense turbulence jet, enabling the air multiplier to realize “air multiplication”, and the time-averaged velocity of the upper “coronary zone” and pressures in near field make greater contributions to the increase of Flow rate. (3) RNG k – e model is reliable on predicting the time-averaged Flow behavior in the Outlet Flow field for the air multiplier.
-
Experimental investigation on the Outlet Flow field structure and the influence of Reynolds number on the Outlet Flow field for a bladeless fan
Applied Thermal Engineering, 2016Co-Authors: Xiang-hong Jin, Hai-shun Deng, Yong-bin LaiAbstract:Abstract The Outlet Flow field of an annular jet for a bladeless fan was investigated experimentally using CTA (Constant Temperature Anemometer) hot-wire system in detail, at five Reynolds numbers ranging from 28,200 to 40,100. From the experiment results, it can be concluded that: (1) the time-averaged velocity in both the horizontal and vertical radial directions, and the time-averaged velocity and turbulence intensity on the axis, all increase with increasing Reynolds number; (2) some variation situations of Sk (skewness) and Ku (kurtosis) of PDF (Probability Density Function) for dimensionless fluctuating velocity on the axis inversely dependent on Reynolds number, indicating that the decrease of Reynolds number intensifies the motion of large-scale coherent structures; (3) the annular jet within the Outlet Flow field starts to converge about at the cross-section of 1.5d (d represents the throat diameter of the Coanda surface) at each Reynolds number; the lower part of the Flow field is combined upwards into the upper part; this combination has been finished about at cross-section of 3d; (4) the combined jet is similar to a classical single jet, the peak decay slope increasing with increasing Reynolds number; also, the intrinsic Flow mechanism of this Flow field structure has been revealed.
Andrea Hildebrandt - One of the best experts on this subject based on the ideXlab platform.
-
Numerical Investigation of the Effect of Different Back Sweep Angle and Exducer Width on the Impeller Outlet Flow Pattern of a Centrifugal Compressor With Vaneless Diffuser
Journal of Turbomachinery, 2007Co-Authors: Andrea Hildebrandt, Magnus GenrupAbstract:This paper presents a numerical investigation of the effect of different back sweep angles and exducer widths on the steady-state impeller Outlet Flow pattern of a centrifugal compressor with a vaneless diffuser. The investigations have been performed with commercial CFD and in-house programmed 1-D codes. CFD calculations aim to investigate how Flow pattern from the impeller is quantitatively influenced by compressor geometry parameters; thereby, the location of wake and its magnitude (Flow angle and relative velocity magnitude) are analyzed. Results show that the increased back sweep impeller provides a more uniform Flow pattern in terms of velocity and Flow deviation angle distribution, and offers better potential for the diffusion process inside a vaneless (or vaned) diffuser. Secondary flux fraction and Flow deviation angle from CFD simulation are implemented into the 1-D two-zone program to improve 1-D prediction results.
