Altair Case Studies Enhancing Safety and Comfort of Japan’s Bullet Trains: A Case Study on Nippon Sharyo and AcuSolve
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Enhancing Safety and Comfort of Japan’s Bullet Trains: A Case Study on Nippon Sharyo and AcuSolve

Altair
Analytics & Modeling - Digital Twin / Simulation
Sensors - Haptic Sensors
Railway & Metro
Transportation
Product Research & Development
Manufacturing Process Simulation
Public Transportation Management
Training
Nippon Sharyo, a leading manufacturer of railroad cars in Japan, faced a complex challenge in enhancing the safety and comfort of their bullet trains. The aerodynamic pressures exerted on the trains, especially when entering and exiting tunnels or passing other trains, posed significant safety risks and discomfort to passengers. The pressure wave created when a train enters a tunnel could cause loud noise and vibration, and the collision of pressure waves when two trains pass each other in a tunnel could produce a force strong enough to push one train away from the other. If not properly managed, these forces could potentially derail the train or at least cause a jarring experience for passengers. Other factors such as unsteady loads when trains pass in open landscapes, the impact of crosswinds, noise from the door frame, and ensuring optimal airflow from heating and air conditioning systems also needed to be considered to maximize passenger safety and comfort.
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Nippon Sharyo, headquartered in Nagoya, Japan, has been in the business of building trains since the late 19th century. Today, it is one of Japan’s most prolific manufacturers of railroad cars, with 1,100 employees building various types of trains such as express, commuter, metro & subway, and light rail vehicles for railroad systems worldwide. The company also designs and produces cars for the growing fleet of bullet trains in Japan. Since the development of the first bullet train in 1964, Nippon Sharyo has manufactured more than 3,200 cars for these high-speed trains, with each train consisting of 8 to 16 cars. The latest versions of the bullet train are capable of carrying passengers at speeds of 300 km/h.
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To address these challenges, Nippon Sharyo turned to Altair’s AcuSolve computational fluid dynamics (CFD) software. Building physical prototypes of the trains was expensive, so the company used AcuSolve to examine the complex airflows impacting the train and its passengers. The software was used in three key areas: safety, amenities, and manufacturing. For safety, AcuSolve helped estimate crosswind loads, wind velocities at ground level, and the aerodynamics of passing trains. In terms of amenities, the software was used to study tunnel entry noise, HVAC flow, aeroacoustics, and vibration in the car trailing the engine. For manufacturing, AcuSolve was used to design the friction stir welding process used in constructing the car. The software allowed Nippon Sharyo to build better products by helping them find the best solutions to increasingly complex physics problems.
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The use of AcuSolve has led to significant operational benefits for Nippon Sharyo. The software has allowed the company to use a single application for comprehensive CFD analysis, reducing costs and bringing vehicles to market faster and more efficiently. Train shapes have been optimized to minimize the noise of tunnel entry, and finite-element analysis has significantly reduced the noise from the door frame. The design of HVAC inlets and outlets has been improved to suit both summer and winter environments, incorporating forced-air convection, free convection, radiation, turbulence, heat transfer, heat loads, and solar radiation. AcuSolve has also enabled engineers to optimize the friction stir welding tool and the welding parameters, improving productivity in the welding of train car sections.
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