chiltern trev
Member
RAIL issue 921 has a side view of an Azuma and a Pendolino on the cover. Both views are full side on and so you can clearly see all the way underneath the carriage.
So it got me thinking about the undercarriage aerodynamics, or not, and then on a wider aerodynamic thinking.
Clearly, the there has been a frontal aerodynamic consideration, but what about other stuff that looks less aerodynamic or varies between trains/carriages?
Passenger doors – recessed or plug? I would have thought a plug door with a smooth bodyside profile is more aerodynamic and weatherproof. A recessed sliding door (Azuma and Javelin) surely is going to disturb the airflow as well as cold air going past the door seal, water ingress through a door seal and then a cold inner panel on the inside of the door pocket (met line A stock was very bad for cold inner panels).
The Azuma shown has recessed grab rails for the cab door so the grab rail are not protruding so some effort there. There are no grab rails shown on the Pendolino – does this mean the driver opens the door first and the grab rails are inside?
Undercarriage stuff. Appears to have a ‘continuous side panel’ on both, similar to Mk3 carriages, so presenting a smoother side profile. So essentially there appears to be a huge under carriage box, with a ‘smooth’ flat bottom and flat blunt end. Does the flat blunt facing the bogie give rise to aerodynamic losses or is a clean flat vertical blunt end the best compromise. Clearly the angle of the blunt end can have a spoiler effect creating lift or down drag and down drag would be more preferable to lift.
And then roof mounted equipment where some designs have a smoothing effect into and out any roof well and other have a vertical drop into a pantograph well. Before considering the effect of the pantograph and insulating pots, etc that sit in the well.
Body jacking points - on the Pendolino these are obvious in the picture and appear top protrude outwards with external bodyside re-inforcing visible in the immediate vicinty of the jacking point- thus sticking out a bit creating a dirty airflow.. On the Azume, these are not visible, so perhaps more built into the internal side of the body panel/floor/etc.
Or maybe the biggest aerodynamic, and thus energy and fuel cost efficiency, is mostly gained by the frontal appearance and all the other considerations are negligible.
So it got me thinking about the undercarriage aerodynamics, or not, and then on a wider aerodynamic thinking.
Clearly, the there has been a frontal aerodynamic consideration, but what about other stuff that looks less aerodynamic or varies between trains/carriages?
Passenger doors – recessed or plug? I would have thought a plug door with a smooth bodyside profile is more aerodynamic and weatherproof. A recessed sliding door (Azuma and Javelin) surely is going to disturb the airflow as well as cold air going past the door seal, water ingress through a door seal and then a cold inner panel on the inside of the door pocket (met line A stock was very bad for cold inner panels).
The Azuma shown has recessed grab rails for the cab door so the grab rail are not protruding so some effort there. There are no grab rails shown on the Pendolino – does this mean the driver opens the door first and the grab rails are inside?
Undercarriage stuff. Appears to have a ‘continuous side panel’ on both, similar to Mk3 carriages, so presenting a smoother side profile. So essentially there appears to be a huge under carriage box, with a ‘smooth’ flat bottom and flat blunt end. Does the flat blunt facing the bogie give rise to aerodynamic losses or is a clean flat vertical blunt end the best compromise. Clearly the angle of the blunt end can have a spoiler effect creating lift or down drag and down drag would be more preferable to lift.
And then roof mounted equipment where some designs have a smoothing effect into and out any roof well and other have a vertical drop into a pantograph well. Before considering the effect of the pantograph and insulating pots, etc that sit in the well.
Body jacking points - on the Pendolino these are obvious in the picture and appear top protrude outwards with external bodyside re-inforcing visible in the immediate vicinty of the jacking point- thus sticking out a bit creating a dirty airflow.. On the Azume, these are not visible, so perhaps more built into the internal side of the body panel/floor/etc.
Or maybe the biggest aerodynamic, and thus energy and fuel cost efficiency, is mostly gained by the frontal appearance and all the other considerations are negligible.
