Dynamic Characteristics Analysis of NuScale in Frequency Domain

2021 ◽  
Author(s):  
Jingrui Yang ◽  
Qian Ma ◽  
Lingtong Han ◽  
Peiwei Sun
Keyword(s):  
Frequency Domain ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Dynamic Characteristics ◽  
Water Desalination ◽  
Design Parameters ◽  
Mechanism Analysis ◽  
Secondary Loop ◽  
Calculation Results

Abstract NuScale is a small nuclear reactor that relies on natural circulation. Its modular production and inherent safety can not only be used to generate electricity in some remote areas, but also provide energy for water desalination and regional heating. However, the dynamic characteristics of the NuScale are different from those of the traditional PWRs because of its passive characteristic. Therefore, it is necessary to study and analyze the system dynamic characteristics of NuScale. The NuScale PWR model is established based on MATLAB&Simulink. It includes point-reactor kinetics model with six groups delayed neutrons, coolant system and steam generator system. The model is established based on the conservation equations of mass, energy and momentum. And the correctness of the model is verified by the comparison between the steady-state calculation results and the design parameters. Transient calculation results are verified by mechanism analysis. To evaluate the dynamic characteristics of NuScale, the sine function changes with different frequencies in reactor reactivity and feedwater mass flow rate are introduced. The amplitude and phase responses of reactor power, secondary loop steam pressure, secondary loop mass flow rate, secondary loop steam temperature, and coolant average temperature are recorded. Then the Bode plot can be drawn with amplitude and phase responses in different frequencies. To evaluate the NuScale dynamic characteristics, frequency domain analysis is performed.

Evaluation of Effects of Different Design Parameters on Axial Fan Performance Using CFD

2015 ◽  
Author(s):  
Racheet Matai ◽  
Savas Yavuzkurt
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cfd Simulation ◽  
Chord Length ◽  
Design Parameters ◽  
Axial Fan ◽  
Blade Length ◽  
Resistor Networks ◽  
Mass Flow Rates

The performance of an industrial fan was simulated using CFD and results were compared with the experimental data. The fan is used to cool a row of resistor networks which dissipate excess energy generated by regenerative power in an inverter application. It has a diameter of 24 inches (0.6096m) and rotates at different speeds ranging from 2500 to 3900 RPM depending on the requirements. CFD simulation results were also verified by simulating performance of the same fan at different speeds and comparing the results with what was expected from fan affinity laws. The CFD results matched almost exactly (with ∼0.2% difference for pressure at a given flow rate) with the performance being predicted by the affinity laws. The effect of variation of different parameters such as the blade length, number of blades, and blade chord length was studied. Increasing the blade length at the same RPM increased the mass flow rate (by ∼17%) for the same pressure. Increasing the chord length while keeping the same number of blades, at a given RPM, made the performance curve (pressure versus flow rate, i.e. PV curve) steeper and blades stalled at a higher mass flow rate (8.77 kg/sec compared to the previous 8.44 kg/sec). For the same total blade surface area, less number of blades with longer chords stalled at lower mass flow rates (9.22 kg/sec for a 33% shorter chord and 36 blades compared to 8.3 kg/sec for the original rotor which had 24 blades).

scholarly journals Transfer Matrix Computation for Wave Action Simulation in an Internal Combustion Engine

2012 ◽  
Author(s):  
Haitham Mezher ◽  
David Chalet ◽  
Pascal Chessé ◽  
Jérôme Migaud ◽  
Vincent Raimbault
Keyword(s):  
Frequency Domain ◽  
Mass Flow Rate ◽  
Transfer Matrix ◽  
Mass Flow ◽  
Flow Rate ◽  
Wave Action ◽  
Pressure Response ◽  
Series Data ◽  
Transfer Matrices ◽  
Dynamic Flow

A new technique for simulating engine pressure waves consisting of linking pressure response and mass flow rate excitation in the frequency domain has been presented. This is achieved on the so-called “dynamic flow bench”. With this new approach, precise, fast and robust results can be obtained while taking into account all the phenomena inherent to compressible unsteady flows. The method exhibited promising results when it was incorporated in a GT-Power/Simulink coupled simulation of a naturally aspirated engine. However, today’s downsized turbocharged engines come with more stringent simulation necessities, where discontinuities such as the charge air cooler (CAC) must be correctly modeled. Simulating such engines with the transfer function methodology is quite difficult because it requires mounting the entire intake line on the bench. Modeling wave action for these engines requires an understanding in the frequency domain of the flow’s characteristics through the different elements that make up the intake line. This leads us to study the acoustic transfer matrices. In order to split the intake line into separate elements, a straight duct of 185mm length is chosen as a first reference. It is mounted on the dynamic flow bench and pressure response is measured after an impulse mass flow excitation. Transfer functions of relative pressure and mass flow rate are then identified at given points upstream and downstream of this reference tube. These functions produce the desired transfer matrix poles. The resulting matrix is validated by inserting the tube in the intake lines of two four-cylinder engines which are modeled in GT-Power. Pressure and mass flow are registered at the measurement points of the tube from the simulation. The time series data upstream of the tube is treated in the frequency domain and the transfer matrix is used to calculate the corresponding downstream values. Measured values from the native simulation and those calculated using the transfer matrix propagation are then compared. Finally, the experimental technique for identifying transfer matrices of more complex elements using two versions of the previous tube is presented.

Optimisation of air-jet vortex generators with respect to system design parameters

1999 ◽  
Vol 103 (1028) ◽  
pp. 475-480 ◽  
Author(s):  
T. P. Bray ◽  
K. P. Garry
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Vortex Generator ◽  
Design Parameters ◽  
Air Jet ◽  
System Input ◽  
System Requirements ◽  
Jet Nozzle ◽  
Definition Of

Abstract A simple technique is proposed that allows the definition of the geometry and characteristics of an air-jet vortex generator to be defined, using the system requirements in practical design. Typically, the aircraft designer is concerned with the mass flow-rate and air pressure requirements of any pneumatic system for inclusion to an airframe. These parameters are not congruent with those for air-jet vortex generator aerodynamic design, and therefore, some tool is required to bridge the gap. Such a tool is proposed, based on empirical methods for the prediction of air-jet vortex generator behaviour. The technique allows the comparison of the vortex strength, and the system inputs (the jet mass flow-rate and the air-jet plenum pressure) for the air-jet, for a range of jet nozzle diameters and jet velocity ratios. Through this comparison, the optimum air-jet design can be reached for a given system input.

Comprehensive Performance Improvement for a 16-Stage Axial Compressor

2021 ◽  
Author(s):  
Grigorii Popov ◽  
Maxim Miheev ◽  
Alexey Vorobyev ◽  
Oleg Baturin ◽  
Vasilii Zubanov
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Design Parameters ◽  
Air Mass ◽  
Stability Margins ◽  
Gas Dynamic ◽  
Low Efficiency

Abstract The paper describes the process of gas-dynamic modernization of a 16-stage axial compressor of an industrial gas turbine unit. Tests of the baseline variant of the compressor revealed a significant shortfall of efficiency, pressure ratio, and stability margins. In addition, the ongoing work on the modernization of the entire engine sets the task to the authors of not just achieving design parameters but significantly exceeding them (air mass flow rate by 6%, pressure ratio by 2%, adiabatic efficiency by 1% relative to the design values). To achieve these goals, a numerical model of the compressor was developed and validated. The characteristics obtained with its help were carefully analyzed. It was found that the front stage group has low efficiency, and the rear stage group is significantly oversized in terms of mass flow rate. Modernization works were significantly hampered by the presence of many stages and many independent variables. For this reason, the problem was solved in several stages. A separate modernization of the first and rear groups of stages was performed. Moreover, methods of mathematical optimization were used when developing the rear block of 10 stages. Then the working processes of the compressor parts were matched. As a result of the research, a variant was found to modernize the existing 16-stage axial compressor, providing an increase in the air mass flow rate by 18%, adiabatic efficiency by 3.5%, and margins of gas-dynamic stability up to 16%.

Numerical Investigation of the Effect of Jet-Flaps in a Transonic Turbine Cascade With Subsonic Operating Conditions

2012 ◽  
Author(s):  
Ping-Ping Chen ◽  
Wei-Yang Qiao ◽  
Pu-Wei Wang
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Operating Conditions ◽  
Slot Width ◽  
Design Parameters ◽  
Pressure Loss Coefficient ◽  
Flap Design ◽  
Variable Geometry Turbine ◽  
Jet Blowing

The objective of this article is to analyze numerically the effect of jet-flap on transonic high-pressure turbine cascades, which is one of usable flow control methods for a variable-geometry turbine (VGT). This paper is mainly on the discussion of the effect of different jet-flap design parameters with subsonic operating conditions: jet mass flow rate, jet slot location, jet blowing direction and jet slot width. With two-dimensional steady simulations, the jet-flap changes the cascade turning, the passage throat velocity distribution and throat area effectively, which will then contribute to a different turbine performance. Using a Cm = 2% pressure side (PS) jet-flap with 1.025mm slot width and counter-axial (-x) jet blowing direction, the incoming mass flow rate is diminished by 16.7%, the turning angle augmented by 3.7 degrees, but with an extended total-pressure loss coefficient from 0.05 (no jets) to 0.09.

scholarly journals Development of a vibrationless sorting system

2021 ◽  
Vol 19 (1) ◽  
pp. e0204
Author(s):  
Selcuk Ugurluay ◽  
Ibrahim Deniz Akcali
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Separation Efficiency ◽  
Mass Movement ◽  
Seed Mass ◽  
Design Parameters ◽  
Operational Parameters ◽  
Equilibrium Angle ◽  
Sorting System

Aim of study: Size classification is essential in many industrial processes. Most classical sorting systems use vibrations as a means of classification function. In this study, a vibration-free sorting system called helical cylindrical screen has been developed against the disadvantages of vibrating systems and proposed to be used in the sorting of crop seeds.Area of study: Adana City, Turkey.Material and methods: The movement of the seed mass on the screen surface was formulated and the mass movement along the circular-helical paths was analytically expressed, leading to some operational parameters for evaluation in the screen design. By combining the mass movement parameters with effective separation conditions, an algorithm was obtained against the desired mass flow rate to determine the appropriate values of the design parameters. Experiments were performed on the machine, which was manufactured to sort peanut seeds into two different sizes, small and large.Main results: The results obtained in the experiments (separation efficiency, mass flow rate, effect of grain size on separation efficiency and equilibrium angle) were compared with the theoretical ones. The separation efficiency of the machine (99% and above) was quite good and is not affected at all by the small size ratio contained in the mixtures. The limitations of the theoretical velocities (axis and tangent) of a seed moving on the cylindrical sieve were found to be consistent with those obtained experimentally.Research highlights: The helical cylindrical sieve can be used for other particulate agricultural products with smooth surfaces such as soybeans, kidney beans, peas, etc.

Experimental performance assessment of a photovoltaic/thermal stepped solar still

2018 ◽  
Vol 29 (3) ◽  
pp. 392-409
Author(s):  
Faramarz Sarhaddi
Keyword(s):  
Energy Efficiency ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Saline Water ◽  
Electrical Power ◽  
Design Parameters ◽  
Solar Still ◽  
Parametric Studies ◽  
Transient Thermal

In this paper, the performance analysis of a stepped solar still connected to photovoltaic thermal collector is carried out numerically and experimentally. A transient thermal model is obtained by writing energy balance for the various components of solar still system (i.e. glass cover, saline water, absorber plate, photovoltaic thermal collector). Also, an expression for the energy efficiency of system is derived. An experimental setup is designed and fabricated. The simulation results are validated by the measured experimental data. Finally, parametric studies are carried out and the effect of various operating and design parameters on the energy efficiency, freshwater productivity, and output electrical power is investigated. It is observed that there is a desired value for the mass flow rate of saline water and the area of photovoltaic thermal collector, which maximizes the energy efficiency. The desired value of the mass flow rate and photovoltaic thermal collector area is 0.068 kg/min and 1.33 m2, respectively. Furthermore, the connection of photovoltaic thermal collector to the stepped solar still improves the freshwater productivity and energy efficiency and it provides additional electrical power for other applications.

Exergy Optimization of a Novel Combination of a Liquid Air Energy Storage System and a Parabolic Trough Solar Collector Power Plant

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Shahram Derakhshan ◽  
Mohammadreza Khosravian
Keyword(s):  
Energy Storage ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Solar Collector ◽  
Design Parameters ◽  
Parabolic Trough ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Parabolic Trough Solar Collector

In this paper, a parabolic trough solar collector (PTSC) plant is combined with a liquid air energy storage (LAES) system. The genetic algorithm (GA) is used to optimize the proposed system for different air storage mass flow rates. The roundtrip exergy ratio is considered as the objective function and pressures of six points and mass flow rates of five points are considered as design parameters. The effects of some environmental and key parameters such as different radiation intensities, ambient temperatures, output pressures of the second compressor, and mass flow rates of the collectors fluid on the exergy ratio are investigated. The results revealed that the system could produce 17526.15 kJ/s (17.5 MW) power in high demands time and 2233.48 kJ/s (2.2 MW) power in low demands time and the system shows that a value of 15.13% round trip exergy ratio is achievable. Furthermore, the exergy ratio decreased by 5.1% when the air storage mass flow rate increased from 10 to 15 kg/s. Furthermore, the exergy ratio decreases by increasing the collectors inside fluid mass flow rate or by decreasing radiation intensity.

scholarly journals Design, fabrication and testing of a cassava pelletizer

2014 ◽  
Vol 60 (No. 4) ◽  
pp. 148-154 ◽  
Author(s):  
O.B. Oduntan ◽  
O.A. Koya ◽  
M.O. Faborode
Keyword(s):  
Moisture Content ◽  
Tensile Stress ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Design Parameters ◽  
Test Results ◽  
Maximum Throughput ◽  
Screw Length ◽  
Level Production

This paper reports on the design of fabrication and testing of a machine for cottage level production of pellets from cassava mash. The pelletizer consists of a barreled screw auger which compresses cassava mash against perforated end plate, through which the pellets are pelletized. The result derived from the calculated design parameters (shaft diameter, tensile stress, torque, screw length, volumetric capacity mass flow rate and power rating) were used for the fabrication. The testing of the pelletizer was determined in terms of throughput of the machine, against the moisture content of the mash (18, 20 and 22% w.b.), die size (4, 6 and 8 mm) and the auger speed (90, 100 and 120 rpm). Test results showed that the pellets with the best quality attributes were obtained from cassava mash at 18% moisture content (w.b.) through the 4 mm die at 90 rpm and a maximum throughput of 54 kg/h.

Performance Deterioration Mechanism Analysis of Natural Draft Cooling Towers Under Crosswind Conditions

2011 ◽  
Author(s):  
Feng-zhong Sun ◽  
Yuan-bin Zhao ◽  
Ming Gao ◽  
You-liang Chen ◽  
Yue-tao Shi
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Transverse Mass ◽  
Cooling Towers ◽  
Mechanism Analysis ◽  
Mass Rate ◽  
Natural Draft ◽  
Performance Deterioration ◽  
Effective Ventilation

Based on the developed three-dimensional computation model of natural draft wet cooling towers, the effect of crosswind on circumferential distribution of air radial pressure gradient and velocity at tower air inlet was studied, and the effect of crosswind on total air inflow rate, transverse mass flow rate, vertical mass flow rate and water temperature drops of the three zones (i.e. spray zone, filling zone and rain zone) were also analyzed. Analysis of crosswind effect on air flow field in heat and mass transfer zone indicates that the induced longitudinal eddy causes reduction of effective ventilation area in filling zone. Results showed that crosswind destroys the uniform air inflow, reducing the total air inflow mass rate and the effective ventilation area of filling zone, resulting in cooling performance deterioration of natural draft wet cooling towers.

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