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).
Page detailing equations and theoretical considerations for calculating engine power and work.
| Identifier | ExFiles\Box 140\1\ scan0219 | |
| Date | 28th March 1938 guessed | |
| -15- WF = work necessary to overcome friction of the engine, ft. lbs. per minute. WB{Mr Brazier/Mr Bell} = the measured brake power output of the engine, ft. lbs. per minute. (2) WE = WB{Mr Brazier/Mr Bell} + WF = WP WM = the measured work necessary to motor the engine at the speed and intake manifold pressure considered, ft. lbs. per minute. (3) = WF = WP From (2) WE = WB{Mr Brazier/Mr Bell} + WF = WP = WB{Mr Brazier/Mr Bell} + WM W1 = the total indicated work, ft. lbs. per minute. = WE + WP (4) = WB{Mr Brazier/Mr Bell} + WM + 144 PV. Where V = volume displacement of engine, cu. ft. per minute. P = intake manifold pressure above atmospheric, lbs. per.sq.in. It will be noted that WB{Mr Brazier/Mr Bell} of Equation 4 is measured by the dynamometer during normal operation of the engine and WM is measured by the dynamometer during motoring of the engine at the intake manifold pressure under consideration. The last term in the equation, the work done by the incoming charge, is calculated from the intake manifold pressure and the swept volume of the engine. In the theoretical calculations of any given boost, the temperature of the incoming charge was taken to be that which was measured during operation of the engine, in order that the relative charge densities for the theoretical conditions might be as nearly equal to the actual as possible. Also, calculations were made for both 'normal' and 'complete' scavenging of the exhaust gas since, as will be pointed out, there is considerable uncertainty as to the degree of scavenging in the actual supercharged engine. There was no other attempt to make the theoretical cycles approach the actual, since the purpose of the calculations was to determine the correlation, if any, between the relative power increases resulting from supercharging an actual engine and the power gains indicated by corresponding ideal cycles. | ||