Final answer:
Extra valves in a four-stroke internal combustion engine increase the flow of gases during the exhaust stroke, improving engine efficiency. The Venturi effect, while related to fluid flow, is used in other applications like carburetors
Step-by-step explanation:
The extra valves in a four-stroke internal combustion engine chamber increase flow in and out of the chamber. The four-stroke engine operates on a cycle that includes the intake stroke, the compression stroke, the power stroke, and the exhaust stroke. During the exhaust stroke, which is a part of the power stroke, the exhaust valve opens allowing some combustion products to escape at almost constant volume (Figure 15.17d). Although most available energy is lost as heat exhaust Q2 at this stage, effective flow during exhaust and intake strokes is crucial for engine efficiency.
Contrastingly, the Venturi constriction principle (Figure 12.24 and 12.25) is applied in devices like carburetors and aspirators to enhance entrainment by creating a pressure differential. While this principle is not directly related to the functioning of exhaust valves, it demonstrates the importance of fluid dynamics in engineering systems such as carburetors and internal combustion engines.