Simulation Of Internal Flow Field Research Articles

Numerical Simulation of Internal Flow Field in Optimization Model of Gas–Liquid Mixing Device

This article studies the influence of structural parameters of the optimization model for the gas–liquid mixing device of a fire truck (compressed air foam lift fire truck, model JP21/G2, made in China) on the liquid phase volume fraction, static pressure, velocity streamline, and the influence of smaller flow rates on the mixing effect. By using the computational fluid dynamics (CFD) software FLUENT 2021 R2, numerical simulations were conducted on the fluid domain model of the gas–liquid mixing device of the JP21/G2 fire truck. The changes in the mixing effect time dimension, liquid phase volume fraction, static pressure, and velocity streamline inside the gas–liquid mixing device were obtained. The optimal mixer structure combination in practical applications was inferred through orthogonal experiments, and the influence of flow rate on the optimal pipe diameter and shortest mixing distance was obtained through variable flow rate simulation experiments. The numerical simulation results show that the presence of bent pipes in the JP21/G2 real vehicle model hinders the gas–liquid mixing process. A straight pipe section of at least 8 m was added after the bent pipe to ensure the mixing effect. The optimal parameter combination for orthogonal experiments had an accurate value of 50°-50°-220 mm. Under the same pipe diameter, using a larger flow rate can achieve better mixing effects.

Simulation of Internal Flow Field in Pulse Thruster Unit

Pulse thrusters are widely used in the attitude control and flight trajectory control of rotating ammunition and vertical launching ammunition, which use own pulse impulse to change the attitude and trajectory of the missile. This paper simulates the internal flow field of a double-layer pulse thruster unit (PTU). The internal flow field of the PTU is simulated at various temperatures based on the three-dimensional compressible N-S governing equations and k-ω SST turbulence model. In addition, the influence of nozzle throat length and divergence half-angle on the performance of pulse T-thruster is analyzed. The simulation results demonstrate that the thrust output error of the PTU is minimum, when the nozzle throat length of the internal pulse thruster is 38 mm. Moreover, the stability of the PTU is improved.

Design and test of pneumatic dedusting equipment for photovoltaic panels

The multi-stage expansion cavity nozzle working with the vacuum dust suction cavity can suppress the re-entrainment of dust while removing the dust on the photovoltaic panels. But the dimension match and the form of the combination have not been studied adequately. In order to obtain the optimal cleaning performance and the energy consumption, an integrated pneumatic dust removal device is proposed. The internal flow field simulation and CFD-DEM simulation are carried out to optimize the size of the dust removal device and the combination form. Then the dust removal device was produced and the dust removal tests were carried out in dry and wet environments. The test results show that when the inlet pressure is 0.8 MPa, the integrated dust removal device can achieve the highest dust removal rate of 96.51% in dry environment and 85.22% in wet environment. Finally, a pneumatic dedusting equipment with the dust removal device was built and the cleaning performance tests were carried out. The test results show that the photovoltaic power generation efficiency of the entire photovoltaic module was increased by about 16.34%, which verified the feasibility of the pneumatic dedusting equipment.

Design and Test of the Structure of Extractor Negative Pressure Zone of Sugarcane Chopper Harvester

Given the problems of the high trash content and loss rate for mechanized sugarcane harvesting, taking the HN4GDL-194 sugarcane chopper harvester extractor developed by South China Agricultural University as the research object, three types of extractor negative pressure structures were designed and internal flow field simulation analysis was conducted. Simulation results showed that the aerodynamic performance of the flow field in the negative pressure area of the extractor negative pressure structure two is the best and the wind velocity and negative pressure are the largest. The measurement results of wind velocity, wind pressure, and flow showed that the changing trend in the actual value of wind velocity and wind pressure is basically consistent with the simulation value. The relative error between the actual flow of the air outlet and the simulation value is less than 10% under different speeds, indicating that the simulation has high accuracy. Field tests of the original extractor and the optimal extractor were conducted. The test results for the trash content showed that when the feeding rate was 1.5 kg/s, there was no significant difference in the trash content between the optimal extractor and the original extractor under various fan speeds. When the feeding rate increased to 7.5 kg/s and the fan speed was low (950 r/min) and medium (1100 r/min), the trash content of the optimal extractor was significantly lower than that of the original extractor, decreasing 2.5% and 1.63%, respectively. The loss rate test results showed that when the fan speed is low and high (1250 r/min), there is no significant difference between the loss rate of the optimal extractor and the original extractor. When the fan speed was 1100 r/min and the feeding rate was 1.5, 4.5, and 7.5 kg/s, compared with the original extractor, the loss rate of the optimal extractor decreased by 0.53%, 0.21%, and 0.19%, respectively.

Numerical Simulation of Internal Flow Field in Turbo-Expander

As everyone pays more attention to energy consumption, it is very meaningful to use natural gas pressure energy for power generation and turbo-expander is an important part of power generation devices. In this paper, the turbo-expander model for pressure energy generation is meshed and numerically simulated based on fluent, and the pressure distribution and velocity distribution in the turbo-expander are obtained. The volute profile is Archimedes spiral, and the impeller is modeled by cfturbo. The main conclusions are as follows: when the number of grids is more than 2.2 million, the simulation results are less affected by the number of grids. The internal basin of the turbo-expander has obvious pressure gradient and velocity gradient. Due to the negative pressure at the elbow of the inlet pipe of the centrifugal effect, the existence of the blade leads to the change of the flow direction. Different watershed planes have different pressure and velocity distributions. The velocity and pressure of the watershed plane near the impeller outlet and the volute outlet are often smaller, but the flow vortex is more intense.

Numerical Simulation of Internal Flow Field of Self-Designed Centrifugal Pump

The two self-designed of centrifugal pump with small vane and centrifugal pump without small vane were simulated numerically to select a centrifugal pump with higher efficiency. The internal flow characteristics of the centrifugal pump was simulated by using Reynolds time-averaged N-S equation and RNG turbulence model to obtain pressure and velocity distribution and the cavitation characteristics were simulated by using SST turbulence model and Schnerr-Sauer cavitation model to obtain the gas volume fraction distribution. The results show that at the same flow rate, the change of velocity in the pump cavity of centrifugal pump with vane is smoother and the gas volume is less, but the back-flow is aggravated near the small vane, especially when interacting with the tongue, and a large amount of gas is generated at the suction surface of the small vane. In addition, the efficiency of centrifugal pump without vane is higher than that of centrifugal pump with vane, which provides a basis for the structural optimization of centrifugal pump.

An optimized roots power machine based on negative displacement theory

Roots power machine has obvious advantages in low and medium temperature waste heat recovery. The existing roots power machine has the problem of internal flow field disturbance, which seriously affects the power generation efficiency of the power machine. In order to solve the problem of disturbance of the internal flow field of roots power machine, the traditional involute rotor roots power machine is improved, and the roots power machine based on negative displacement involute rotor is proposed. The structure model and turbulence model of roots power machine are constructed, and the internal flow field simulation of roots power machine is realized by CFD. The pressure contour and torque change of roots power machine before and after improvement are compared, and the experimental research on the improved structure is carried out. The results show that the intensity of flow field disturbance in the modified involute rotor roots power machine decreases, and the working performance of the roots power machine improves,which provides a reference for the structural improvement and performance optimization of roots power machine.

Numerical Simulation of Internal Flow Field and Structural Optimum Design for the diesel engine SCR Catalytic Converter

A three-dimensional model and finite element model of the diesel engine SCR catalytic converter were established by using ANSYS software. The numerical simulation of the internal flow field for the diesel engine SCR catalytic converter was performed. The results show that the pressure loss of the catalytic converter is larger and the velocity distribution in the front of substrate is nonuniform. On this base, the effects of the diameters and lengths of the substrate on the catalytic converter’s internal flow field characteristic were studied. The results show that when the substrate’s length increases, the pressure loss increases and the velocity distribution uniformity in the front of substrate becomes worse. When the diameter of substrate increases, the pressure loss decreases and the velocity distribution uniformity in the front of substrate becomes better. Therefore, the structure of catalytic converter was optimized. Through the optimization of the structure, the velocity distribution in the front of substrate is more uniform. The passing capacity of substrate is increased. The conversion efficiency of catalytic converter is improved. The back pressure is reduced.

Experimental and simulation study on a novel uniform air/smoke exhaust device in subway

A novel π-shape device (π-D) was developed based on air full pressure supply theory to realize the uniform air/smoke exhaust for long duct with enormous vents in subway tunnel. To validate its performance, numerical simulation of internal flow field of the duct with π-D was conducted. Then an experimental 65-meter-long exhaust duct with π-Ds was set up in accordance with the real size. The air exhaust velocities of each vent and the total head losses along the main duct were measured. Both experimental and simulation results showed that the proposed new device could be designed and equipped flexibly into the long air/smoke exhaust duct. It would significantly enhance the ventilation uniformity, reduce the airflow resistance by 50%-65%, and achieve above 20% of distribution energy saving as well.

Numerical Simulation of Internal Flow Field in Blast Furnace Slag Dry Granulating Device

In this paper, CFD numerical simulation method was adopted to study the internal flow field of experimental dry granulating device of blast furnace slag and to research the impact of equipment structure and wind speed on cooling effectiveness. Main content included the internal flow field uniformity under different blade type and number of inlets. The results showed that the internal flow field in strip-blades device was more uniform than fan-shaped blades device. With the increase of air inlets quantity, the internal flow field in device became more uniform and stable, especially when there were 8 air inlets in the equipment.

Review and optimization of main parameters of pump turbine in Xiangshuijian pumped-storage power station

Mixed transportation technology of oil and gas is an efficient transportation method of offshore oil fields, in which oil and gas multiphase pump is the key equipment. In this paper, aimed at a single compression stage unit of a helico-axial multiphase pump prototype, a numerical simulation of internal flow field is carried out. It is assumed that the flow is steady and the two-phase flow pattern is bubble flow. Water is the main phase and incompressible air is the second phase. The change of external characteristics is compared in different inlet gas volume fraction (GVF) condition; the internal flow field characteristics such as velocity fields, pressure fields, and two-phase distributions are discussed as well. The result shows that the differential pressure and the hydraulic efficiency decrease with the increase of GVF, and there are some significant changes in internal flow fields. Further, under the condition of 10% inlet GVF, the changes of external characteristics and internal flow field of the pump when the air bubble diameter varies are compared. The result shows that the differential pressure and the hydraulic efficiency decrease with the increase of bubble diameter.

The two-phase flow analysis of helico-axial oil-gas multiphase pump for offshore oil fields

Mixed transportation technology of oil and gas is an efficient transportation method of offshore oil fields, in which oil and gas multiphase pump is the key equipment. In this paper, aimed at a single compression stage unit of a helico-axial multiphase pump prototype, a numerical simulation of internal flow field is carried out. It is assumed that the flow is steady and the two-phase flow pattern is bubble flow. Water is the main phase and incompressible air is the second phase. The change of external characteristics is compared in different inlet gas volume fraction (GVF) condition; the internal flow field characteristics such as velocity fields, pressure fields, and two-phase distributions are discussed as well. The result shows that the differential pressure and the hydraulic efficiency decrease with the increase of GVF, and there are some significant changes in internal flow fields. Further, under the condition of 10% inlet GVF, the changes of external characteristics and internal flow field of the pump when the air bubble diameter varies are compared. The result shows that the differential pressure and the hydraulic efficiency decrease with the increase of bubble diameter.

Study on internal flow field simulation accuracy of centrifugal impellers based on different meshing types

Meshing is an important preprocessing part of numerical simulation for water pump, which has important influence on numerical results. In order to simulate internal flow field in water pump more accurately, three different types of grids with hexahedron, polyhedron and tetrahedron are applied to simulate the internal flow field of impeller by using improved k-ω SST turbulence model. Besides, simulating results are compared with PIV testing results by evaluating their accuracy. Numerical simulation results show that the proposed simulation method reduces the requirement for computer configuration. Internal flow field of the reflux pump will be captured more accurately using polyhedral meshes with improved k-ω SST turbulence model, which has a high accuracy and high computational efficiency as well as strong adaptability.

Numerical Simulation of Internal Flow Field, Electromagnetic Field and Temperature Field in Deep-Water Motor

In this paper, considering the heat exchange between the ends of stator&rotor and lubricating oil, the internal flow field model is established to analyse the flow state. The variation law of the pressure drops in the internal flow field and the friction loss of the rotor surface are specified. The operation characteristic of the motor and the variation law of the magnetic field loss are obtained through the analysis of motor magnetic field. Based on the results of internal flow field and magnetic field, the temperature distribution law of motor is obtained. Compared with the result of the temperature simulation in which only air gap path is considered, the stator temperature shows totally different distribution law, and the stator temperature increases from 32°C to 42°C. Compared with the result of the temperature simulation without considering heat source loss change, the maximum temperature of the motor decreases from 71°C to 49°C. The results show that the ends of stator&rotor and the variation of heat source loss can influence the temperature simulation results.

A Performance Test and Internal Flow Field Simulation of a Vortex Pump

Vortex pumps have good non-clogging performance and are widely used in the fluid transportation of food, sewage treatment, and mineral and coal slurry transportation. In order to design and manufacture a vortex pump with good performance and establish a method of optimum design, we must master the internal flow rules of the pump. Based on the self-design vortex pump (32WB8-12) experiment, the discharge-pump head (qv-H), discharge-pump shaft power (qv-P), discharge-pump efficiency (qv-η), and discharge-critical net positive suction head (qv-NPSHc) curves are obtained, and the qv-NPSHc curve shows an opposite tendency compared with the centrifugal pump. With the mathematical model selected with respect to the optimal condition, the three-dimensional internal flow within the vortex pump has been numerically simulated by a renormalization group k-ε (RNG k-ε) turbulence model. The static pressure (ps) and velocity distribution of the impeller and the middle section of the volute at 0°, 90°, 180°, and 270° are obtained, and the performance curves have been fitted using a CFX-calculated energy parameter. It was illustrated that the velocity field is relatively disordered and the flow in the impeller region is of a forced vortex character. The flow in the volute is similar to that of the combined vortex with backflow, which is a non-axisymmetric unsteady flow with quite high turbulence intensity. These factors are the main reasons for the relatively low efficiency of the vortex pump. The measurement of flow field in volute with a five-hole probe was conducted, and it is demonstrated that the numerical results are in good agreement with the flow field measurement data. An upward pressure gradient forms in the portal area of the impeller, and it is confirmed that the lowest pressure point is located in the upper position of the impeller hub. It is revealed that for the vortex pump to have advanced suction and anti-cavitation performance, the lowest pressure in the pump should be −4 × 104 Pa and it should be located at the center of the vortex chamber cavity.

Research on the Numerical Simulation of Internal Flow Field and Energy Efficiency of Ventilator

In the present study, the effects of ventilator geometries on the its performance were numerically simulated using the computational fluid dynamics (CFD) program. For a certain type ventilator, three-dimensional inner flow field was derived firstly, such as local flow field at the meridional and rotary plane of ventilator, the gap flow between the impeller and air outlet, and the secondary flows in impeller channel were studied in detail, and some suggestions are given to improve the profile of velocity. The above results would be helpful to the optimization and modification of ventilator.

The Structure Design and Numerical Simulation of Internal Flow Field with High Efficiency Low Resistance Cyclone

Introduces the structure and main characteristics of high efficiency low resistance cyclone dust removal, the use of fluid finite element analysis software for the internal flow field is simulated. It can be concluded that gas flow in the cyclone separator, pressure field, velocity field, such as distribution, and on the basis of the flow field calculation results for the structure design about analyzed and discussed.

Study on Numerical Simulation of Internal Flow Field for the Multi Blade Centrifugal Fan

This paper points out that the traditional design method of multi blade centrifugal fan are great uncertainty in selecting the structure parameters: lead to many design results, do many tests. Internal flow field of multi blade centrifugal fan was simulated with the computational fluid dynamics software Fluent, and the numerical results are analyzed. Comparison of the numerical results with the test results shows that numerical simulation has good accuracy and reliability. The design program and a design example is gived according to the design theory of multi blade centrifugal fan. Method is verified by numerical simulation for the example. Test results show that the design program is reliable.

Research on Internal Flow Field Simulation of Hydropower Station Pressure Steel Pipe Based on FLUENT

The research object of this paper is one of the pressure steel pipes which is installed in hydropower station of agricultural and animal husbandry college, use the computational fluid dynamics software FLUENT to 3D numerical simulation for internal flow field of this pressure steel pipe, obtain the distribution of internal flow field and flow velocity. At the same time, analyze the bending position, verified the accuracy and rationality of the simulation.

Numerical Simulation of Internal Flow Field in Mixed Flow Fan

The numerical simulation of internal flow field of a mixed-flow fan was carried out on the star-CD platform. Three-dimensional steady turbulent flow is calculated using the standard k-ɛ turbulence model, and the pressure distribution, velocity distribution and other important flow phenomenon inside the fan are obtained. The number of meshes has important influence on the result, meanwhile, fan inlet, impeller, outlet interact with each other. The results of numerical simulation can accurately analyze the fan flow field. The results of numerical simulation can accurately analyze the fan flow field structure, and provide guidance for further optimization and improvement of the fan.