scholarly journals Flow-Field Characteristics of High-Temperature Annular Buoyant Jets and Their Development Laws Influenced by Ventilation System

2013 ◽  
Vol 2013 ◽  
pp. 1-11
Author(s):  
Yi Wang ◽  
Yanqiu Huang ◽  
Jiaping Liu ◽  
Hai Wang ◽  
Qiuhan Liu
Keyword(s):  
High Temperature ◽  
Flow Field ◽  
Cross Section ◽  
Flow Rate ◽  
Ventilation System ◽  
Volumetric Flow Rate ◽  
Outer Diameter ◽  
Exhaust Hood ◽  
Buoyant Jets ◽  
Flow Field Characteristics

The flow-field characteristics of high-temperature annular buoyant jets as well as the development laws influenced by ventilation system were studied using numerical methods to eliminate the pollutants effectively in this paper. The development laws of high-temperature annular buoyant jets were analyzed and compared with previous studies, including radial velocity distribution, axial velocity and temperature decay, reattachment position, cross-section diameter, volumetric flow rate, and velocity field characteristics with different pressures at the exhaust hood inlet. The results showed that when the ratio of outer diameter to inner diameter of the annulus was smaller than 5/2, the flow-field characteristics had significant difference compared to circular buoyant jets with the same outer diameter. For similar diameter ratios, reattachment in this paper occurred further downstream in contrast to previous study. Besides, the development laws of volumetric flow rate and cross-section diameter were given with different initial parameters. In addition, through analyzing air distribution characteristics under the coupling effect of high-temperature annular buoyant jets and ventilation system, it could be found that the position where maximum axial velocity occurred was changing gradually when the pressure at the exhaust hood inlet changed from 0 Pa to −5 Pa.

scholarly journals Building a bridge between industry and theory on the example of a new ventilation system

2019 ◽  
Vol 213 ◽  
pp. 01001 ◽  
Author(s):  
Kazimierz Peszyński
Keyword(s):  
Mathematical Modelling ◽  
Velocity Distribution ◽  
Flow Velocity ◽  
Cross Section ◽  
Flow Rate ◽  
Rectangular Cross Section ◽  
Ventilation System ◽  
Volumetric Flow Rate ◽  
Ventilation Ducts

The paper presents the possibilities of simplified determination of the air volumetric flow rate in ventilation ducts. This problem occurred during the tests of local losses in the elements of a new ventilation system based on ducts with a rounded rectangular cross-section. The presented method requires mathematical modelling of the flow velocity distribution in the ducts. The paper presents four models of the velocity distribution. The necessity of using so many models resulted from the wide coverage of the tested sections: Amax/Amin= 46.88.

scholarly journals A Study on Ceiling Temperature Distribution and Critical Exhaust Volumetric Flow Rate in a Long-Distance Subway Tunnel Fire with a Two-Point Extraction Ventilation System

Energies ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1411 ◽  
Author(s):  
Peng Zhao ◽  
Zhongyuan Yuan ◽  
Yanping Yuan ◽  
Nanyang Yu ◽  
Tao Yu
Keyword(s):  
Temperature Distribution ◽  
Flow Rate ◽  
Empirical Equation ◽  
Ventilation System ◽  
Volumetric Flow Rate ◽  
Subway Tunnel ◽  
Smoke Control ◽  
Long Distance ◽  
Tunnel Fire ◽  
Ceiling Temperature

Smoke control is a crucial issue in a long-distance subway tunnel fire, and a two-point extraction ventilation system is an effective way to solve this problem, due to the characteristics of controlling the smoke in a limited area and removing high-temperature and toxic smoke in time. In this study, the ceiling temperature distribution and the critical exhaust volumetric flow rate to control the smoke in the zone between two extraction vents were investigated in a long-distance subway tunnel fire with a two-point extraction ventilation system. Experiments were carried out in a 1/20 reduced-scale tunnel model based on Froude modeling. Factors, including the heat release rate (HRR), the extraction vent length, the internal distance between two extraction vents and exhaust volumetric flow rate, were studied. Smoke temperature below the ceiling, exhaust volumetric flow rate and smoke spreading configurations were measured. The ceiling temperature distribution was analyzed. Meanwhile, an empirical equation was developed to predict the critical exhaust volumetric flow rate based on the one-dimensional theory, experimental phenomenon and the analysis of forces acting at the smoke underneath the extraction vent. The coefficients in the empirical equation were determined by experimental data. Compared with the experimental results, the developed empirical equation can predict the critical exhaust volumetric flow rate well. Research outcomes in this study will be beneficial to the design and application of two-point extraction ventilation system for a long-distance subway tunnel fire.

scholarly journals Analysis of a novel high performance induction air heater

2018 ◽  
Vol 22 (Suppl. 3) ◽  
pp. 843-853 ◽  
Author(s):  
Umit Unver ◽  
Ahmet Yuksel ◽  
Alper Kelesoglu ◽  
Fikret Yuksel ◽  
Halil Unver
Keyword(s):  
Flow Field ◽  
Cross Section ◽  
Flow Rate ◽  
Thermal Efficiency ◽  
High Performance ◽  
Control Volume ◽  
Thermal Power ◽  
Heat Losses ◽  
Flow Rates ◽  
Air Mass

This study represents an experimental and numerical investigation of the enhanced prototypes of the induction air heaters. For this purpose, flow field is enhanced in order to avoid turbulence. The air mass flow rate, outlet construction and the application of insulation of the outer surface of the heater were selected as the performance enhancing parameters. Depending on the exit construction, the new designed prototypes are named as K-2 and K-3. Experiments were performed under two groups for three various flow rates. In the first group, non-insulation situation is examined. In the second group tests, insulation is applied to the outside of windings and inlet-outlet flaps which constitute the boundary of the control volume for the prevention of heat losses. The increasing flow rate boosted the thermal efficiency by 9%. Each of insulation and enlarging exit cross section increased the thermal efficiency by 13%. It was observed that the thermal power transferred to air with the new prototypes increased about 246 W more than the previous designs. The thermal efficiencies of the K-2 and K-3 type heaters were calculated as 77.14% and 87.1%, respectively.

scholarly journals Analysis of the velocity distribution in different types of ventilation system ducts

2018 ◽  
Vol 180 ◽  
pp. 02081 ◽  
Author(s):  
Kazimierz Peszyński ◽  
Lukasz Olszewski ◽  
Emil Smyk ◽  
Daniel Perczyński
Keyword(s):  
Velocity Profile ◽  
Velocity Distribution ◽  
Cross Section ◽  
Power Law ◽  
Flow Rate ◽  
Fundamental Problem ◽  
Ventilation System ◽  
Different Types ◽  
Actual Profile ◽  
Ventilation Duct

The paper presents the results obtained during the preliminary studies of circular and rectangular ducts before testing the properties elements (elbows, tees, etc.)of rectangular with rounded corners ducts. The fundamental problem of the studies was to determine the flow rate in the ventilation duct. Due to the size of the channel it was decided to determine the flow rate based on the integration of flow velocity over the considered cross-section. This method requires knowledge of the velocity distribution in the cross section. Approximation of the measured actual profile by the classic and modified Prandtl power-law velocity profile was analysed.

Optimization of an Innovative Rotary Shaft Pump (RSP)

2006 ◽  
Vol 128 (6) ◽  
pp. 1281-1288 ◽  
Author(s):  
Jacob C. Allen ◽  
Phillip M. Ligrani
Keyword(s):  
Flow Rate ◽  
Volumetric Flow Rate ◽  
Maximum Flow ◽  
Performance Data ◽  
Outer Diameter ◽  
Hydraulic Efficiency ◽  
Rotary Pump ◽  
Optimal Arrangement ◽  
Pump Performance ◽  
Pump Head

This paper describes the optimization of rotary shaft pump performance, which is accomplished by comparing the performance of four different centrifugal rotary pump configurations: hooked blades pump, backward-curved blades ID=12.7mm pump, contoured base pump, and backward-curved blades ID=19.1mm pump. Each of these devices utilizes a unique and simple impeller design where the blades are directly integrated into a shaft with an outer diameter of 25.4mm. Presented for each pump are performance data including volumetric flow rate, pump head, and hydraulic efficiency. When pumping water, the most optimal arrangement with the hooked impeller blades produces a maximum flow rate of 3.22L∕min and a pump head as high as 0.97m.

Lateral ventilation performance for removal of pulsating buoyant jet under the influence of high-temperature plume

2019 ◽  
Vol 29 (4) ◽  
pp. 543-557 ◽  
Author(s):  
Yi Wang ◽  
Lei Cao ◽  
Yanqiu Huang ◽  
Yingxue Cao
Keyword(s):  
High Temperature ◽  
Ventilation System ◽  
Capture Efficiency ◽  
Buoyant Jet ◽  
Buoyant Jets ◽  
Future Design ◽  
Two Factors ◽  
Building Ventilation ◽  
Ventilation Performance ◽  
Instantaneous Increase

Lateral exhaust systems have commonly been applied to capture polluted buoyant jets in many industrial processes, such as casting and metallurgy. Compared with the normal conditions of design manuals, the capture efficiency of a lateral exhaust hood (LEH) is often weakened by two factors in actual processes: the unsteady buoyant jet released from the operating surface, and the plume formed above a high-temperature workpiece placed between the LEH and the operating surface. In this study, through experiments and numerical simulations, a pulsatile phenomenon was found in the velocity and concentration distribution of the unsteady buoyant jet. Results show that the contaminate escape ratio is pulsatile; it rises with the instantaneous increase in the buoyant jet velocity and gradually decreases to a constant value. This study not only reveals the air distribution of pulsating buoyant jet but also analyses the effect of the pulsating buoyant jet and high-temperature plume on lateral ventilation system capture efficiency and provides a possible guidance for future design of new building ventilation technologies.

scholarly journals Experimental and numerical investigation of thermal and flow conditions inside a large pharmaceutical storage after the ventilation system failure

2021 ◽  
pp. 346-346
Author(s):  
Ilija Tabasevic ◽  
Rastko Jovanovic ◽  
Dragan Milanovic
Keyword(s):  
Temperature Distribution ◽  
Flow Field ◽  
Flow Rate ◽  
Ventilation System ◽  
Pharmaceutical Products ◽  
System Failure ◽  
Flow Conditions ◽  
Cfd Simulations ◽  
Depth Analysis ◽  
Good Agreement

Safe storage of pharmaceutical products is of great importance due to potential hazards for human health. The aim of this study was to assess the ability of pharmaceutical storage to recover design temperature during ventilation system recovery. The performed CFD simulations showed good agreement with experimental temperature measurements. Numerical results allowed in-depth analysis of flow field and temperature distribution inside the storage. It was discovered that the flow field is highly non-uniform, which consequently leads to an uneven temperature distribution of pallets with products. However, a high inlet mass flow rate ensured that all pallets reach the designed temperature.

Numerical Studies on the Performance of Saccardo Ventilation System in Emergency Fire Scenarios

2014 ◽  
Vol 527 ◽  
pp. 146-151
Author(s):  
Rouhollah Ganjiazad ◽  
Ali Kazemipour ◽  
Hossein Afshin ◽  
Bijan Farhanieh
Keyword(s):  
Flow Rate ◽  
Inclination Angle ◽  
Ventilation System ◽  
Volumetric Flow Rate ◽  
Smoke Plume ◽  
Numerical Studies ◽  
Air Jet ◽  
Before And After ◽  
Fire Scenarios ◽  
Inclination Angles

In this study, the influence of volumetric flow rate and inclination angle of air jet is evaluated on the performance of a Saccardo ventilation system in a straight rectangular tunnel in case of fire. Simultaneous effects of volumetric flow rate and inclination angle of jet exiting the Saccardo nozzle on the behavior of smoke plume is considered by studying the structure of velocity profile before the fire source. It is found that this factor has a remarkable influence on the behavior of smoke plume and therefore, on the temperatures experienced near the fire. Besides, the influence of tunnel slope on the performance of the Saccardo system to sweep the plume is investigated. It is shown that the slope effect on the behavior of smoke plume and temperature profiles is completely different for locations before and after the fire, in both negative and positive slopes. Finally a range of volumetric flow rates and inclination angles is proposed as the optimized range of performance in an emergency fire scenario.

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