A generalized model for vehicle thermodynamic loss management and technology concept evaluation

Abstract

The objective of this paper is to develop a generalized loss management model to account for the usage of thermodynamic work potential in vehicles of any type.The key to accomplishing this is creation of a differential representation for vehicle loss as a function of operating condition. This differential model is then integrated through time to obtain an analytical estimate for total usage (and loss) of work potential consumed by each loss mechanism present during vehicle operation. The end result of this analysis is a better understanding of how the work potential initially present in the fuel, batteries, etc. is partitioned amongst all losses relevant to the vehicle's operation. The loss partitioning estimated from this loss management model can be used in conjunction with cost accounting systems to gain a better understanding of underlying drivers on vehicle manufacturing and operating costs. In addition, loss management models are useful for evaluation of technology models during the preliminary phases of design because they provide a common basis to measure the impact of disparate technologies.

Methods for the design of energy efficient high speed aerospace vehicles

“…Greene (17) examined the role of entropy for induced drag minimisation on low-speed airfoils using concepts related to this earlier work. Roth, et al (18,19) have usefully extended work potential methods to a vehicle airframe with a turbine engine propulsion system and overall vehicle system loss management. Finally, the complete relationship between availability, entropy, and overall vehicle performance is derived and discussed in Riggins, et al (2) ; in this reference the critical importance of the vehicle wake mixing/equilibrium process is fully demonstrated.…”

Method for Propulsion Technology Impact Evaluation via Thermodynamic Work Potential

“…The loss management method alluded to previously is nothing more than a formalized means of quantifying and tracking this usage of work potential throughout the vehicle mission. 8 The central concept allowing the presentation of a unified FoM for both aerothermodynamic and weight impact of new technologies is the notion of chargeable gross weight. To understand this, consider the earlier statement that fuel has a known quantity of work potential stored within.…”

Aerodynamic drag loss chargeability and its implications in the vehicle design process

“…The development of this loss deck is tailored such that aerodynamic losses can be partitioned for maximum usefulness when applied in a loss management model. 1,2,3 However, it will be shown that the aerodynamic loss deck has value in and of itself when used as an analysis tool to understand the sources of aerodynamic loss.…”