Q1: The diameter (d) of a nozzle fixed at the end of a pipe (diameter D, length L) for maximum energy, is

ANS:C -

The diameter (d) of a nozzle fixed at the end of a pipe (with diameter D and length L) for maximum energy depends on the specific conditions of the fluid flow and the desired outcome. However, for maximum energy conversion, we usually aim to achieve the maximum velocity at the nozzle exit. The velocity of the fluid exiting the nozzle is dependent on the velocity head, which is proportional to the square of the velocity. Therefore, to maximize the velocity head and hence the kinetic energy of the fluid, we want to maximize the velocity of the fluid exiting the nozzle. The diameter d of the nozzle is crucial in determining the velocity of the fluid exiting the nozzle. According to the principles of fluid dynamics, for maximum velocity and hence maximum energy conversion, the diameter of the nozzle d should be carefully chosen to ensure efficient flow expansion. In general, the diameter d of the nozzle for maximum energy is often chosen such that it matches the critical flow conditions, where the pressure at the nozzle exit matches the ambient pressure. This condition allows for the maximum possible expansion of the fluid jet and thus maximizes the velocity of the fluid exiting the nozzle. However, the exact determination of the nozzle diameter for maximum energy involves considerations of fluid properties, nozzle geometry, flow conditions, and specific energy conversion goals. It often requires theoretical analysis, computational fluid dynamics (CFD) simulations, or experimental testing to optimize the nozzle design for maximum energy conversion efficiency.