Thermally choked flow occurs when the addition of heat to a compressible fluid flowing through a duct or channel causes the Mach number to reach unity at the exit. Further heat addition beyond this point will not increase the flow rate; instead, it will increase the pressure upstream. As an example, consider a gas flowing through a constant area duct with frictional losses present. If heat is added, the gas accelerates. If sufficient heat is added to accelerate the gas to Mach 1 at the exit, the flow is considered to be thermally choked. Calculating the parameters under these conditions involves analyzing the interplay between heat addition, frictional effects, and the conservation equations (mass, momentum, and energy).
Understanding the phenomena of thermally choked flow is essential in various engineering applications, particularly in the design and analysis of combustion systems, high-speed propulsion devices, and chemical reactors. Predicting the heat transfer limitations and pressure distributions within these systems is vital for optimizing performance and preventing component failure. The study of this phenomenon is rooted in the development of gas dynamics and thermodynamics, with significant contributions from researchers seeking to improve the efficiency and safety of thermal systems.
