Numerical analysis of operating conditions of a continuous-action HF chemical laser

1979 ◽  
Vol 15 (1) ◽  
pp. 75-81 ◽  
Author(s):  
A. V. Lavrov ◽  
V. A. Pospelov ◽  
A. V. Fedotov ◽  
M. L. Shur
Keyword(s):  
Numerical Analysis ◽  
Operating Conditions ◽  
Continuous Action ◽  
Chemical Laser

Experimental and numerical analysis to identify the performance limiting mechanisms in solid-state lithium cells under pulse operating conditions

2019 ◽  
Vol 21 (41) ◽  
pp. 22740-22755 ◽  
Author(s):  
Mei-Chin Pang ◽  
Yucang Hao ◽  
Monica Marinescu ◽  
Huizhi Wang ◽  
Mu Chen ◽  
...  
Keyword(s):  
Solid State ◽  
Numerical Analysis ◽  
Energy Density ◽  
Lithium Ion Batteries ◽  
Lithium Batteries ◽  
Safety Concern ◽  
Lithium Ion ◽  
Thermal Runaway ◽  
Operating Conditions ◽  
Lithium Cells

Solid-state lithium batteries could reduce the safety concern due to thermal runaway while improving the gravimetric and volumetric energy density beyond the existing practical limits of lithium-ion batteries.

Numerical simulation and experimental performance research of cylindrical vane pump

2021 ◽  
pp. 095440622110200
Author(s):  
Yiqi Cheng ◽  
Xinhua Wang ◽  
Waheed Ur Rehman ◽  
Tao Sun ◽  
Hasan Shahzad ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Rotational Velocity ◽  
Geometric Theory ◽  
Mechanical Efficiency ◽  
Operating Conditions ◽  
Experimental Results ◽  
Field Analysis ◽  
Total Efficiency ◽  
Three Dimensional Model ◽  
Vane Pump

This study presents a novel cylindrical vane pump based on the traditional working principle. The efficiency of the cylindrical vane pump was verified by experimental validation and numerical analysis. Numerical analysis, such as kinematics analysis, was performed in Pro/Mechanism and unsteady flow-field analysis was performed using ANSYS FLUENT. The stator surface equations were derived using the geometric theory of the applied spatial triangulation function. A three-dimensional model of the cylindrical vane pump was established with the help of MATLAB and Pro/E. The kinematic analysis helped in developing kinematic equations for cylindrical vane pumps and proved the effectiveness of the structural design. The maximum inaccuracy error of the computational fluid dynamics (CFD) model was 5.7% compared with the experimental results, and the CFD results show that the structure of the pump was reasonable. An experimental test bench was developed, and the results were in excellent agreement with the numerical results of CFD. The experimental results show that the cylindrical vane pump satisfied the three-element design of a positive-displacement pump and the trend of changes in efficiency was the same for all types of efficiency under different operating conditions. Furthermore, the volumetric efficiency presented a nonlinear positive correlation with increased rotational velocity, the mechanical efficiency showed a nonlinear negative correlation, and the total efficiency first increased and then decreased. When the rotational velocity was 1.33[Formula: see text] and the discharge pressure was 0.68[Formula: see text], the total efficiency reached its maximum value.

Numerical Analysis of the Heat and Mass Transfer Characteristics in an Autothermal Methane Reformer

2010 ◽  
Vol 7 (5) ◽  
Author(s):  
Joonguen Park ◽  
Shinku Lee ◽  
Sunyoung Kim ◽  
Joongmyeon Bae
Keyword(s):  
Mass Transfer ◽  
Numerical Analysis ◽  
Heat And Mass Transfer ◽  
Steam Reforming ◽  
Space Velocity ◽  
Reaction Model ◽  
Operating Conditions ◽  
Local Thermal Equilibrium ◽  
Inlet Temperature ◽  
Transfer Characteristics

This paper discusses a numerical analysis of the heat and mass transfer characteristics in an autothermal methane reformer. Assuming local thermal equilibrium between the bulk gas and the surface of the catalyst, a one-medium approach for the porous medium analysis was incorporated. Also, the mass transfer between the bulk gas and the catalyst’s surface was neglected due to the relatively low gas velocity. For the catalytic surface reaction, the Langmuir–Hinshelwood model was incorporated in which methane (CH4) is reformed to hydrogen-rich gases by the autothermal reforming (ATR) reaction. Full combustion, steam reforming, water-gas shift, and direct steam reforming reactions were included in the chemical reaction model. Mass, momentum, energy, and species balance equations were simultaneously calculated with the chemical reactions for the multiphysics analysis. By varying the four operating conditions (inlet temperature, oxygen to carbon ratio (OCR), steam to carbon ratio, and gas hourly space velocity (GHSV)), the performance of the ATR reactor was estimated by the numerical calculations. The SR reaction rate was improved by an increased inlet temperature. The reforming efficiency and the fuel conversion reached their maximum values at an OCR of 0.7. When the GHSV was increased, the reforming efficiency increased but the large pressure drop may decrease the system efficiency. From these results, we can estimate the optimal operating conditions for the production of large amounts of hydrogen from methane.

Numerical Analysis of Non-Radial Blading in a Low Speed and Low Pressure Turbine for Electric Turbocompounding Applications

2021 ◽  
Author(s):  
Eva Alvarez-Regueiro ◽  
Esperanza Barrera-Medrano ◽  
Ricardo Martinez-Botas ◽  
Srithar Rajoo
Keyword(s):  
Numerical Analysis ◽  
Numerical Simulations ◽  
Thermal Stresses ◽  
Waste Heat ◽  
Pressure Ratio ◽  
Low Pressure ◽  
Turbine Rotor ◽  
Operating Conditions ◽  
Blade Angle ◽  
Low Speed

Abstract This paper presents a CFD-based numerical analysis on the potential benefits of non-radial blading turbine for low speed-low pressure applications. Electric turbocompounding is a waste heat recovery technology consisting of a turbine coupled to a generator that transforms the energy left over in the engine exhaust gases, which is typically found at low pressure, into electricity. Turbines designed to operate at low specific speed are ideal for these applications since the peak efficiency occurs at lower pressure ratios than conventional high speed turbines. The baseline design consisted of a vaneless radial fibre turbine, operating at 1.2 pressure ratio and 28,000rpm. Experimental low temperature tests were carried out with the baseline radial blading turbine at nominal, lower and higher pressure ratio operating conditions to validate numerical simulations. The baseline turbine incidence angle effect was studied and positive inlet blade angle impact was assessed in the current paper. Four different turbine rotor designs of 20, 30, 40 and 50° of positive inlet blade angle are presented, with the aim to reduce the losses associated to positive incidence, specially at midspan. The volute domain was included in all CFD calculations to take into account the volute-rotor interactions. The results obtained from numerical simulations of the modified designs were compared with those from the baseline turbine rotor at design and off-design conditions. Total-to-static efficiency improved in all the non-radial blading designs at all operating points considered, by maximum of 1.5% at design conditions and 5% at off-design conditions, particularly at low pressure ratio. As non-radial fibre blading may be susceptible to high centrifugal and thermal stresses, a structural analysis was performed to assess the feasibility of each design. Most of non-radial blading designs showed acceptable levels of stress and deformation.

Damping Behavior of Blades From Small Radial Turbines

2015 ◽  
Author(s):  
David Hemberger ◽  
Dietmar Filsinger ◽  
Hans-Jörg Bauer
Keyword(s):  
Numerical Analysis ◽  
Dynamic Properties ◽  
Forced Response ◽  
Operating Conditions ◽  
Fe Model ◽  
Structural Damping ◽  
Aerodynamic Damping ◽  
Damping Behavior ◽  
Aerodynamic Properties ◽  
Radial Turbines

Next to excitation forces and the dynamic properties of mistuned structures the damping behavior is a key feature to evaluate the dynamic turbine blade response and thus the HCF life of a bladed disk (blisk). Just as the determination of the mistuning properties and the assessment of the vibration excitation, the evaluation of damping is also subject to uncertainty especially considering the wide operating range of a small radial turbine of a turbocharger. Since the total damping is composed of material damping, structural damping and aerodynamic damping, which are affected by parameters, like the eigenform of the vibration, the magnitude of the vibration amplitude and aerodynamic properties, the total damping can be strongly dependent on the operating conditions. The study at hand provides results from investigations that allow estimating the contribution of aerodynamic damping on the total damping. Experimental and numerical analysis of radial turbines from turbochargers for vehicular engines with variable turbine inlet vanes were performed. Measurements under different environmental conditions such as at rest and during operation, as well as unsteady CFD calculations and, coupled flow and structural calculations were carried out. A change in total damping could be found depending on the density of the surrounding gas by vibration measurements in operation on the hot gas test bench. But it was also shown that the total damping is decisively influenced by the mistuning of the structure. On one side the structural damping is varied by the variation in mistuned blade vibration amplitudes and otherwise the aerodynamic damping is influenced by the different inter blade phase angles (IBPA ) due to the mistuning, which is a symptom of geometric differences and material inhomogeneity in the wheels. Finally, the estimated total damping values were utilized in forced response calculations using a mistuned FE-model of a real turbine and excitation forces from unsteady CFD calculation. The magnitudes of the measured vibration amplitudes were compared with results from numerical analysis to validate the numerical model with focus on the investigation about the total damping. The deviation between the results was ±10% for different eigenforms and excitation orders.

Numerical analysis of unsteady flow under high‐head operating conditions in Francis turbine

2010 ◽  
Vol 27 (3) ◽  
pp. 365-386 ◽  
Author(s):  
Xiao Yexiang ◽  
Wang Zhengwei ◽  
Yan Zongguo ◽  
Li Mingan ◽  
Xiao Ming ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Unsteady Flow ◽  
Operating Conditions ◽  
Francis Turbine ◽  
High Head

Numerical Analysis of the Flow Inside a Centrifugal Compressor’s Vaneless Diffuser and Volute

2001 ◽  
Author(s):  
Hooman Rezaei ◽  
Abraham Engeda ◽  
Paul Haley
Keyword(s):  
Experimental Data ◽  
Numerical Analysis ◽  
Mass Flow ◽  
Operating Conditions ◽  
Vaneless Diffuser ◽  
Flow Angle ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Minimum Medium ◽  
Good Agreement

Abstract The objective of this work was to perform numerical analysis of the flow inside a modified single stage CVHF 1280 Trane centrifugal compressor’s vaneless diffuser and volute. Gambit was utilized to read the casing geometry and generating the vaneless diffuser. An unstructured mesh was generated for the path from vaneless diffuser inlet to conic diffuser outlet. At the same time a meanline analysis was performed corresponding to speeds and mass flow rates of the experimental data in order to obtain the absolute velocity and flow angle leaving the impeller for those operating conditions. These values and experimental data were used as inlet and outlet boundary conditions for the simulations. Simulations were performed in Fluent 5.0 for three speeds of 2000, 3000 and 3497 RPM and mass flow rates of minimum, medium and maximum. Results are in good agreement with the experimental ones and present the flow structures inside the vaneless diffuser and volute.

Numerical analysis of the output performance of a pulsed HBr chemical laser

1979 ◽  
Vol 50 (9) ◽  
pp. 5615-5623 ◽  
Author(s):  
M. Iyoda ◽  
M. Udagawa ◽  
M. Obara ◽  
T. Fujioka
Keyword(s):  
Numerical Analysis ◽  
Chemical Laser ◽  
Output Performance
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