Top fuel dragsters (right) as the quickest accelerating cars inthe world, and the fastest competitors reach speeds of 335mph,completing a 1000ft run in just 3.64s. The 0 to 100mph time duringthese runs is as little as 0.8 seconds. The 4-stroke enginegeometry used in these dragsters can be seen in Table 1. Theseengines run on nearly pure nitromethane (properties in Table2).
Table1: Top Fuel Engine Geometry
Displacement, Vd [cm3] | 8190 |
Bore [cm] | 10.6 |
Stroke [cm] | 11.4 |
Compression Ratio [-] | 7.0 |
Configuration | V8 |
Peak Power [bhP] | 10,000 @ 8000rpm |
Table2: Nitromethane Properties
Chemical Formula | CH3NO2 |
Density [kg/L] | 1.140 |
LHV [MJ/kg] | 11.2 |
A) (10pts) Calculate the BMEP in [bar] produced by a top fueldragster at peak power.
(Answer: BMEP = 136.6bar)
B) (25pts) A top fuel dragster consumes about 11.2 gal/s ofnitromethane at full throttle, and operates at an equivalenceratio, ϕ, of 5.0. Determine the air flow and fuel flow per cylinderat full throttle in [kg/s] (1gal = 3.785L). (Answer:ṁfuel= 6.04 kg/s per cylinder, ṁair= 2.052kg/s per cylinder)
C) (15pts) Determine the brake fuel conversion efficiency of atop fuel engine operating at peak power. (Answer:ηf= 1.38%)
