Numerical study of the optimization of the pitch angle of an alternative jet fan in a longitudinal tunnel ventilation system

2009 ◽  
Vol 24 (2) ◽  
pp. 164-172 ◽  
Author(s):  
Vittorio Betta ◽  
Furio Cascetta ◽  
Marilena Musto ◽  
Giuseppe Rotondo
Keyword(s):  
Pitch Angle ◽  
Numerical Study ◽  
Ventilation System ◽  
Tunnel Ventilation ◽  
Jet Fan

Numerical Study of Pitch Angle on H-Type Vertical Axis Wind Turbine

2012 ◽  
Vol 499 ◽  
pp. 259-264
Author(s):  
Qi Yao ◽  
Ying Xue Yao ◽  
Liang Zhou ◽  
S.Y. Zheng
Keyword(s):  
Wind Turbine ◽  
Pitch Angle ◽  
Numerical Study ◽  
Vertical Axis ◽  
Azimuth Angle ◽  
Power Coefficient ◽  
Cfd Model ◽  
Vertical Axis Wind Turbine ◽  
Sliding Mesh ◽  
Mesh Technique

This paper presents a simulation study of an H-type vertical axis wind turbine. Two dimensional CFD model using sliding mesh technique was generated to help understand aerodynamics performance of this wind turbine. The effect of the pith angle on H-type vertical axis wind turbine was studied based on the computational model. As a result, this wind turbine could get the maximum power coefficient when pitch angle adjusted to a suited angle, furthermore, the effects of pitch angle and azimuth angle on single blade were investigated. The results will provide theoretical supports on study of variable pitch of wind turbine.

A New Advance in Tunnel Ventilation Design Planning

2017 ◽  
Author(s):  
Mark P. Colino ◽  
Elena B. Rosenstein
Keyword(s):  
Ventilation System ◽  
National Fire Protection Association ◽  
Capital Cost ◽  
Smooth Transition ◽  
Mechanical Equipment ◽  
Tunnel Ventilation ◽  
Tunnel Fire ◽  
Ventilation Shaft ◽  
Emergency Ventilation ◽  
Ventilation Fan

The new train signaling, traction power and tunnel ventilation system coordination guidelines enacted in National Fire Protection Association (NFPA) Standard 130 have brought the necessity and cost of tunnel ventilation fan shafts into greater focus. The guidelines were aimed at coordinating the three aforementioned rail systems to control the number of trains that could be between successive ventilation shafts during an emergency — in recognition of the fact that the best protection to both incident and non-incident train passengers and crew is to allow no more than one train in each ventilation zone. Though based in safety, these new NFPA guidelines can substantially expand the capital cost and environmental impact of new rail tunnel projects by adding more ventilation shafts and tunnel fan equipment to the scope of work. In addition, the resulting increase in the required number of ventilation shafts and tunnel fan equipment can hinder existing railroad properties as they seek to either increase their train throughput rates, or reduce their tunnel electrical infrastructure. Fortunately, a new kind of emergency ventilation shaft has been developed to facilitate compliance with the NFPA 130 Standard without the excessive capital cost and far-reaching environmental impacts of a traditional emergency ventilation shaft. This new kind of emergency ventilation shaft is called the Crossflue. The Crossflue is a horizontal passage between parallel rail tunnels with a single ventilation fan-motor unit installation. The Crossflue fan is designed to transfer air/smoke flows from one (occupied, incident) tunnel to another (unoccupied, non-incident) tunnel — thereby protecting the incident tunnel at the expense of the non-incident tunnel. The Crossflue passage has angled construction to allow a smooth transition of airflows both into and out of the adjoining tunnels. In addition to the fan, the Crossflue contains a ventilation damper, sound attenuators, ductwork transitions and flexible connectors within the fan equipment line-up; the functionality of all this mechanical equipment is described in the paper. To preserve underground space and minimize the rock excavation, the Crossflue fan is both remotely-powered and remotely-controlled; the fan is only operated as part of a pre-programmed response to tunnel fire events. The methodology utilized to design the Crossflue was taken from the Subway Environmental Design Handbook (SEDH); the SEDH [1] was specifically developed for rail tunnel ventilation design and is the preeminent reference volume in the industry. In summary, the Crossflue provides a dual benefit of achieving NFPA 130 compliance, while at the same time minimizing the construction, equipment, environmental, and energy costs of a traditional tunnel ventilation shaft.

CFD analysis on ventilation characteristics of jet fan with different pitch angle

2014 ◽  
Vol 18 (3) ◽  
pp. 812-818 ◽  
Author(s):  
Seung-Chul Lee ◽  
Seungho Lee ◽  
Juhee Lee
Keyword(s):  
Pitch Angle ◽  
Cfd Analysis ◽  
Jet Fan

scholarly journals Numerical study of the air distribution in the Crew Quarters on board of the International Space Station

2019 ◽  
Vol 85 ◽  
pp. 02015 ◽  
Author(s):  
Charles Berville ◽  
Matei-Răzvan Georgescu ◽  
Ilinca Năstase
Keyword(s):  
Numerical Simulations ◽  
International Space Station ◽  
Numerical Study ◽  
Ventilation System ◽  
Space Station ◽  
Air Distribution ◽  
Thermal Manikin ◽  
Airflow Rate ◽  
International Space ◽  
Airflow Distribution

The current concept of Crew Quarters on board of the International Space Station has several issues according to the crew member’s feedback. Major issues concern noise levels, the accumulation of CO2 and the quality of the air distribution. Our study targets the airflow distribution, to diagnose this issue, we realise a series of numerical simulations (CFD) based on a real scale replica of the Crew Quarters. Simulations were set with a zero-gravity mode and with the theoretical air parameters inside the SSI. The geometry includes a thermal manikin having the neutral posture of a body in the absence of gravity. Numerical simulations were run for the three different air flow rates provided by the current ventilation system. Results have shown that the air distribution inside the Crew Quarter is insufficient for low airflow rates but becomes acceptable for the higher airflow rate, however the higher airflow rate can potentially produce draught discomfort.

Numerical Assessment of Fan-Ducting Coupling for Gas Turbine Ventilation Systems

2015 ◽  
Author(s):  
Alessandro Corsini ◽  
Giovanni Delibra ◽  
Stefano Minotti ◽  
Stefano Rossin
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Static Pressure ◽  
Numerical Study ◽  
Characteristic Curve ◽  
Ventilation System ◽  
Maximum Pressure ◽  
Term Operation ◽  
Axial Fans ◽  
Pressure Discontinuity

Gas turbines enclosures entail a high number of auxiliary systems which must be preserved from heat, ensuring therefore the long term operation of the internal instrumentation and of the data acquisition system. A dedicated ventilation system is designed to keep the enclosure environment sufficiently cool and dilute any gas coming from potential internal leakage to limiting explosion risks. These systems are equipped with axial fans, usually fed with air coming from the filter house which provides air to the gas turbine combustion system, through dedicated filters. The axial fans are embedded in a ducting system which discharges fresh air inside the enclosure where the gas turbine is housed. As the operations of the gas turbine need to be guaranteed in the event of fan failure, a backup redundant system is located in a duct parallel to the main one. One of the main requirements of a ventilation fan is the reliability over the years as the gas turbine can be installed in remote areas or unmanned offshore platforms with limited accessibility for unplanned maintenance. For such reasons, the robustness of the ventilation system and a proper understanding of coupling phenomena with the axial fan is a key aspect to be addressed when designing a gas-turbine system. Here a numerical study of a ventilation system carried out with RANS and LES based methodologies will be presented where the presence of the fan is synthetized by means of static pressure discontinuity. Different operations of the fans are investigated by means of RANS in order to compare the different operating points, corresponding to 1) clean and 2) dirty filters operations, 3) minimum and 4) maximum pressure at the discharge section. Large Eddy Simulations of the same duct were carried out in the maximum loading condition for the fan to investigate the unsteady response of the system and validate its correct arrangement. All the simulations were carried out using OpenFOAM, a finite volume open source code for CFD analysis, treating the filters as a porous medium and the fan as a static pressure discontinuity according to the manufacturer’s characteristic curve. RANS modelling was based on the cubic k-ε model of Lien et al. while sub-grid scale modelling in LES was based on the 1 equation model of Davidson. Computations highlighted that the ventilation system was able to work in similarity for flow rates between 15 m3/s and 23.2 m3/s and that the flow conditions onto the fan suggest that the aerodynamic stress on the device could be reduced introducing in the duct flow straighteners or inlet guided vanes.

scholarly journals Numerical Study of Smoke Propagation in a Simulated Fire in a Wagon Within a Subway Tunnel

2008 ◽  
Author(s):  
Felipe Vittori ◽  
Luis Rojas-Solo´rzano ◽  
Armando J. Blanco ◽  
Rafael Urbina
Keyword(s):  
Numerical Study ◽  
Ventilation System ◽  
Road Tunnel ◽  
Subway Tunnel ◽  
Longitudinal Ventilation ◽  
Emergency Ventilation ◽  
Tunnel Section ◽  
Fire Scenarios ◽  
Subway Stations ◽  
Set Up

This work deals with the numerical (CFD) analysis of the smoke propagation during fires within closed environments. It is evaluated the capacity of the emergency ventilation system in controlling the smoke propagation and minimizing the deadly impact of an eventual fire in a wagon within the Metro de Caracas subway tunnel on the passengers safety. For the study, it was chosen the tunnel section between Teatros and Nuevo Circo subway stations, which consists of two parallel independent twin tunnels, connected through a transverse passage. The tunnels are provided by a longitudinal ventilation system, integrated by a set of reversible fans located at both ends of the tunnels. Three stages were considered in the study: (a) Model set up; (b) Mesh sensitivity analysis; (c) Validation of the physical-numerical parameters to be used in the numerical model; and (d) Simulation of fire scenarios in Metro de Caracas subway stations. Stages (b)–(c), aimed to testing and calibrating the CFD tool (ANSYS-CFX10™), focused on reproducing experimental data from Vauquelin and Me´gret [1], who studied the smoke propagation in a fire within a 1:20 scale road tunnel. Stage (d) critical scenarios were established via a preliminary discussion with safety experts from Metro de Caracas, in order to reduce the computer memory and the number of simulations to be performed. The analyses assessed the reliability of escape routes and alternative paths for the evacuation of passengers. Additionally, the smoke front movement was particularly computed, as a function of time, in order to determine the possible presence of the “backlayering” phenomenon [5]. Results demonstrate the strengths and weaknesses of the current ventilation system in the event of a fire in the subway tunnel, and suggest new strategies to address this potentially lethal event to minimize the risks for passengers.

Analysis of a new strategy for emergency ventilation and escape scenario in long railway tunnels in the fire mode

2018 ◽  
Vol 233 (3) ◽  
pp. 239-250 ◽  
Author(s):  
Behtash Hakimzadeh ◽  
Mohammad Reza Talaee
Keyword(s):  
Ventilation System ◽  
Control Panel ◽  
Fire Dynamics ◽  
Railway Tunnel ◽  
Rescue Operation ◽  
Tunnel Ventilation ◽  
Precise Control ◽  
Ventilation Shaft ◽  
Emergency Ventilation ◽  
Safe Path

The creation of a safe path for evacuating passengers from a tunnel during fire accidents is an important function of a mechanical ventilation system in tunnels. In this work, the operation of emergency ventilation in the fire mode in a long railway tunnel with push–pull ventilation shafts is analyzed using a fire dynamics simulator. As the passenger trains are lengthy – and so is a tunnel – when trains pass through a tunnel, the position of fire on the train becomes an important parameter for rescuing the passengers through a safe path. The novelty of this study is in the design of emergency ventilation scenarios that consider the position of fire on the train in addition to the tunnel ventilation shafts. For this case study, a lengthy (8 km) urban railway tunnel in Tehran with four rail tracks and eight ventilation shafts is considered for designing emergency ventilation scenarios and control of fire products. The fire source is a passenger train wagon with a 25-MW heat release rate. It is shown that, during the rescue operation of the passengers, the location of fire on the train may lead to reverse the ventilation scenario compared with the traditional ones that use only the tunnel shafts. Also, it is observed that there is a region with 50 m radius around each ventilation shaft, i.e. the absolute exhaust zone, where the ventilation system must be set at the exhaust mode due to the presence of fire, to minimize the spreading of fire products downstream. All the logical scenarios of the tunnel ventilation system are designed and demonstrated to create a critical ventilation velocity in the tunnel, which would help in developing a more precise control panel of the tunnel in the fire mode.

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