From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Tests measuring the cooling air flow through a fan-cooled chassis dynamo.
| Identifier | ExFiles\Box 60\4\ Scan236 | |
| Date | 18th October 1934 | |
| Hs{Lord Ernest Hives - Chair}/FJA./MJ.8/18.10.34. CHASSIS DYNAMO COOLING AIR FLOW. In connection with the design of fan-cooled chassis dynamos, some tests have been made using the supercharger rig to find the rate of air flow likely to be produced. From the design (R.R.Sch.755) we calculate that there will be a maximum pressure difference across the machine, including the fan, of 2.0" of water at 5000 r.p.m. We accordingly took a dynamo (to R.R.Sch.481) and arranged it as shown in attached sketch providing as free a flow as possible through the machine. The air supply was adjusted to 2.0" of water at the entry to the machine, the temperature being 27°C. The flow then measured was 2.24 lbs/min. or 30.4 cu.ft./min. This means that the machine is equivalent to a sharp-edged circular orifice (taking a coefficient of discharge of 0.6) of 1.26" diameter. Some further readings at 31°C. and 48°C. showed slight reductions in the flow but not of an important amount. It is understood that the air supply is to be from outside the bonnet. During the test we caused the machine to revolve electrically but found that this made no difference whatever to the air flow. Hs{Lord Ernest Hives - Chair}/F.J.Allen. | ||