CFD analysis of a monorail vehicle under the influence of crosswind and oncoming traffic

In order to increase mobility in rural areas and to support public transport, an autonomous monorail vehicle (MonoCab [1]) is developed, which is able to use old unused railroad tracks. A narrow design makes it possible for two vehicles to pass each other on one track in two-way traffic. A fully automated driving mode allows the vehicle to be ordered on demand via app. Due to the design on only two wheels, monorail vehicles must be able to react quickly to environmental influences, such as wind, in order to prevent overturning. To avoid critical tilt angles during travel and ensure ride comfort, gyroscopic stabilizers and linear masses are used to hold the vehicle in the desired position in real time. In this study, the vehicle behavior is investigated by determining flow coefficients when crosswind occurs. For this purpose, a guideline from the German railroad standard DIN EN 14067-6 is applied. This standard specifies a flow around the vehicle in 5-degree increments from 0 degrees to 50 degrees, followed by 10-degree increments to 90 degrees, to simulate crosswinds from different directions. The flow vector is calculated from the vehicle speed and the wind speed, taking into account the wind angle. In order to better detect occurring instabilities at the vehicle geometry, the simulation series is calculated with the transient solver pimpleFoam. These simulations are used to generate characteristic curves using calculated moment coefficients. In addition, the pressure surge is examined, which occurs when two vehicles pass each other in oncoming traffic. This is achieved using the dynamic mesh solver overPimpleDyMFoam for overlaid meshes. Two opposing vehicles with projected track gauge spacing are defined with a linear motion function of maximum vehicle speed magnitude. During the passing of both vehicles at maximum speed, the forces and moments around the point of contact on the rail are recorded

CFD analysis of a monorail vehicle under the influence of crosswind and oncoming traffic

In order to increase mobility in rural areas and to support public transport, an autonomous monorail vehicle (MonoCab [1]) is developed, which is able to use old unused railroad tracks. A narrow design makes it possible for two vehicles to pass each other on one track in two-way traffic. A fully automated driving mode allows the vehicle to be ordered on demand via app. Due to the design on only two wheels, monorail vehicles must be able to react quickly to environmental influences, such as wind, in order to prevent overturning. To avoid critical tilt angles during travel and ensure ride comfort, gyroscopic stabilizers and linear masses are used to hold the vehicle in the desired position in real time. In this study, the vehicle behavior is investigated by determining flow coefficients when crosswind occurs. For this purpose, a guideline from the German railroad standard DIN EN 14067-6 is applied. This standard specifies a flow around the vehicle in 5-degree increments from 0 degrees to 50 degrees, followed by 10-degree increments to 90 degrees, to simulate crosswinds from different directions. The flow vector is calculated from the vehicle speed and the wind speed, taking into account the wind angle. In order to better detect occurring instabilities at the vehicle geometry, the simulation series is calculated with the transient solver pimpleFoam. These simulations are used to generate characteristic curves using calculated moment coefficients. In addition, the pressure surge is examined, which occurs when two vehicles pass each other in oncoming traffic. This is achieved using the dynamic mesh solver overPimpleDyMFoam for overlaid meshes. Two opposing vehicles with projected track gauge spacing are defined with a linear motion function of maximum vehicle speed magnitude. During the passing of both vehicles at maximum speed, the forces and moments around the point of contact on the rail are recorded

CORRELATION DEVELOPMENT FOR JET IMPINGEMENT HEAT TRANSFER AND FORCE ON A MOVING CURVED SURFACE

The effect of jet Reynolds number, jet exit angle, the nozzle to surface distance, jet to jet spacing on the heat transfer, and pressure force performance from multiple impinging round jets on a moving curved surface have been numerically evaluated. Two correlations are developed and validated for the average Nu number and the pressure force coefficient and the agreement between the CFD and correlations was reasonable. The surface motion effect becomes more pronounced on the Nu number distribution for low jet Re number, high jet to jet spacing, large jet to surface distance, and angled jets. The pressure force coefficient is highly dependent on the jet to surface distance and jet angle but relatively insensitive to jet Re number and jet to jet spacing. © 2022, International Scientific Information, Inc.. All rights reserved

Numerical Optimization of Heat Transfer from Multiple Jets Impinging on a Moving Curved Surface for Industrial Drying Machines

Jet impingements enhance the heat and mass transfer rate in industrial drying machines. The designer should optimize the design parameters of industrial drying equipment to achieve maximum heat transfer rate. The heat transfer between multiple jets and a moving curved surface is more difficult to study due to the changing boundaries and the effect of surface curvature but is also very relevant in industrial drying applications. SST k-ω turbulence model is used to simulate a real geometry for industrial drying applications. The SST k-ω turbulence model succeeded with reasonable accuracy in reproducing the experimental results. The jet to surface distance, jet to jet spacing, jet inlet velocity, jet angle, and surface velocity are chosen as the design parameters. For the optimization of the impinging round jet, the average Nu number on the moving curved surface is set as the objective functions to be maximized. The SHERPA search algorithm is used to search for the optimal point from the weighted sum of all objectives method. One correlation is developed and validated for the average Nu number. It is found that the maximum average Nu number correlates with high values of jet inlet velocity (Vj), jet angle (θ) and jet to jet spacing (S/d) and low values of the jet to surface distance (H/d) and relative surface velocity (VR). The agreement in the prediction of the average Nu number between the numerical simulation and correlation is found to be reasonable and all the data points deviate from the correlation by less than 4%