scholarly journals Energy Characteristics of Full Tubular Pump Device with Different Backflow Clearances Based on Entropy Production

2021 ◽  
Vol 11 (8) ◽  
pp. 3376
Author(s):  
Fan Meng ◽  
Yanjun Li ◽  
Ji Pei
Keyword(s):  
Energy Dissipation ◽  
Dissipation Rate ◽  
Guide Vane ◽  
Flow Simulation ◽  
Suction Side ◽  
Additional Energy ◽  
Energy Characteristics ◽  
Evaluation Standard ◽  
Shaft Power ◽  
3D Unsteady Flow

In this study, the entropy theory was used as the evaluation standard of energy dissipation, and the effect of backflow clearance (the gap between motor rotor and motor shell) on energy characteristics of a full tubular pump was investigated by 3D unsteady flow simulation. The calculated results validated through testing shows that backflow clearance produces additional head loss and the rotation of the motor rotor requires more shaft power. The additional energy losses lead to a significant decline in the efficiency of tubular pump device. Under design conditions, the total dissipation of backflow clearance, rear guide vane, and outlet passage decreases with the increase of clearance radius, but that of the impeller decreases first and then rises with the increase of clearance radius. In addition, the increase of the clearance radius leads to disorderly flow pattern in the impeller. The total dissipation rate on the impeller suction side and near the impeller inlet increases with the increase of backflow clearance radius, but that on the impeller suction side decreases with the increase of backflow clearance radius. The total dissipation rate of the suction side of the guide vane and the wall of the outlet passage decreases with the increase of backflow clearance radius. This work can provide an intuitive analysis of the energy dissipation caused by backflow clearance and reference for engineering applications of full tubular pump.

The evolution of turbulent bursts: the b—ε model

1994 ◽  
Vol 5 (4) ◽  
pp. 537-557 ◽  
Author(s):  
M. Bertsch ◽  
R. Dal Passo ◽  
R. Kersner
Keyword(s):  
Partial Differential Equations ◽  
Energy Dissipation ◽  
Energy Density ◽  
Differential Equations ◽  
Dissipation Rate ◽  
Turbulent Energy ◽  
Energy Dissipation Rate ◽  
Self Similar ◽  
Similar Solutions ◽  
Semi Empirical

We study the semi-empirical b—ε model which describes the time evolution of turbulent spots in the case of equal diffusivity of the turbulent energy density b and the energy dissipation rate ε. We prove that the system of two partial differential equations possesses a solution, and that after some time this solution exhibits self-similar behaviour, provided that the system has self-similar solutions. The existence of such self-similar solutions depends upon the value of a parameter of the model.

Upper bounds on the energy dissipation in turbulent precession

1996 ◽  
Vol 321 ◽  
pp. 335-370 ◽  
Author(s):  
R. R. Kerswell
Keyword(s):  
Experimental Data ◽  
Energy Dissipation ◽  
Viscous Dissipation ◽  
Upper Bound ◽  
Dissipation Rate ◽  
Oblate Spheroid ◽  
Upper Bounds ◽  
Precession Rate ◽  
Long Cylinder

Rigorous upper bounds on the viscous dissipation rate are identified for two commonly studied precessing fluid-filled configurations: an oblate spheroid and a long cylinder. The latter represents an interesting new application of the upper-bounding techniques developed by Howard and Busse. A novel ‘background’ method recently introduced by Doering & Constantin is also used to deduce in both instances an upper bound which is independent of the fluid's viscosity and the forcing precession rate. Experimental data provide some evidence that the observed viscous dissipation rate mirrors this behaviour at sufficiently high precessional forcing. Implications are then discussed for the Earth's precessional response.

scholarly journals Energy-Dissipation Limits in Variance-Based Computing

2018 ◽  
Vol 17 (02) ◽  
pp. 1850013
Author(s):  
Sri Harsha Kondapalli ◽  
Xuan Zhang ◽  
Shantanu chakrabartty
Keyword(s):  
Energy Dissipation ◽  
Thermal Noise ◽  
Operating Conditions ◽  
Superior Performance ◽  
Energy Scavenging ◽  
Logic Device ◽  
Additional Energy ◽  
Fundamental Limits ◽  
Bit Flip ◽  
Theoretical Results

Variance-based logic (VBL) uses the fluctuations or the variance in the state of a particle or a physical quantity to represent different logic levels. In this paper, we show that compared to the traditional bi-stable logic representation, the variance-based representation can theoretically achieve a superior performance trade-off (in terms of energy dissipation and information capacity) when operating at fundamental limits imposed by thermal noise. We show that, in addition to the universal KT ln(1/[Formula: see text]) energy dissipation required for a single bit flip, a bi-stable logic device needs to dissipate at least 4.35[Formula: see text]KT/bit of energy, whereas under similar operating conditions, a VBL device reduces the additional energy dissipation requirements down to sub-KT/bit. These theoretical results are generally enough to be applicable to different instantiations and variants of VBL ranging from digital processors based on energy-scavenging or to processors based on the emerging valleytronic devices.

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