(70o) An Approximate Model for Discharge Density Associated with Critical Flow

The purpose of this presentation (paper) is to present an approximate model derived from the entropy balance associated with isentropic, choked flow utilizing the van der Waal equation of state and an approximate form of the van der Waal equation for high pressures that will provide the stagnation density. This will provide the form of the model where a non-dimensional parameter related to the deviation from isothermal behavior will be estimated via three non-dimensional numbers related to pressure, temperature and ratio of specific heats of the system. The model will be validated against three gases which are ideal and thermodynamically perfect, ideal but not thermodynamically perfect, and a real gas. Pressures will range up to 4 MPa. The relationship of this model against other models in the literature will be explored and its relationship to the Omega method will be discussed.