ANSYS > Case Studies > CFX Simulation Enhances Ventilation System at Grand Central Terminal

CFX Simulation Enhances Ventilation System at Grand Central Terminal

Technology Category

Sensors - Air Pollution Sensors
Sensors - Environmental Sensors

Applicable Industries

Buildings
Railway & Metro

Applicable Functions

Procurement
Product Research & Development

Use Cases

Port Automation
Virtual Reality

Services

System Integration

About The Customer

The customer in this case study is the Grand Central Terminal (GCT), the principal hub of the MTA Metro-North Railroad, the second largest commuter railroad in the U.S. GCT serves approximately 240,000 customer trips each weekday and some 70 million trips per year. The terminal, which opened in 1913, underwent a $175 million restoration project in 1997. As part of the restoration, the GCT concourses now lead to the 'trainshed,' one of the largest underground structures in Manhattan, consisting of 30 platforms on two levels. The trainshed has faced significant ventilation challenges due to its large size and the widespread use of air-conditioned equipment.

The Challenge

The Grand Central Terminal (GCT), a principal hub of the MTA Metro-North Railroad, faced a significant challenge in ventilating its trainshed, one of the largest underground structures in Manhattan. The trainshed, which occupies 2.5 million square feet, was designed long before the advent of air conditioning, and the widespread use of air-conditioned equipment added waste heat into the facility. The existing ventilation, provided by sidewalk grilles and a few small vent shafts, was insufficient for the large area of the trainshed. During summer months, ground level temperatures were typically 15 degrees Fahrenheit above ambient. Previous attempts to improve ventilation had been costly and ineffective. Hatch Mott McDonald (HMM), a full-service engineering firm, was contracted to conduct a preliminary study using computational fluid dynamics (CFD) to understand the current ventilation conditions and the impact of changes made in recent years.

The Solution

HMM implemented CFX software from ANSYS as the CFD modeling tool for this project. To reduce computational requirements, HMM created two separate models for the upper and lower levels of the trainshed, treating the results of each as a boundary condition for the other. The model was refined to include heat sources such as the trains, the air conditioners on the trains, and the thermal inertia of the buildings above the trainshed. The model was validated by comparing its predictions to temperature and humidity measurements along the platform. The CFX software enabled engineers to evaluate the cost and benefits of a wide range of potential design improvements, making it possible to obtain the most benefits for the funds available to improve ventilation. The excellent correlation of the model generated confidence in CFD analysis and led to the award of a $2.3 million contract to a new ventilation system.

Operational Impact

The implementation of the CFX software from ANSYS provided a comprehensive solution to the ventilation challenges faced by the Grand Central Terminal. The software enabled the engineers to create detailed models of the trainshed, which helped them understand the current ventilation conditions and the impact of changes made in recent years. The model's predictions correlated well with actual temperature and humidity measurements, validating its accuracy. This led to a better understanding of the ventilation problem and the identification of effective solutions. The use of the CFX software turned guesswork into fact, enabling the engineers to make informed decisions about potential design improvements. The successful implementation of the software not only improved the ventilation system but also increased passenger comfort, employee comfort, and the service life of the trains.

Quantitative Benefit

CFX software enabled the evaluation of a wide range of potential design improvements in a cost-effective manner.
The excellent correlation of the model generated confidence in CFD analysis and led to the award of a $2.3 million contract to a new ventilation system.