Utilizing an Adjustment Factor to Scale Between Multiple Fidelities Within a Design Process: A Stepping Stone to Dialable Fidelity Design

Abstract

The conceptual and preliminary design stages of aircraft design have traditionally been two separate, time intensive design phases. However, the concept of dialable fidelity is one in which the gap between these two phases, conceptual and preliminary design, is bridged by introducing physics into the design process at an earlier stage than traditionally employed. This introduction of physics at an earlier stage eliminates the need for separate conceptual and preliminary design phases and consequently reduces total design time. The concept of dialable fidelity does however pose certain obstacles such as determining how and when to dial or switch between different fidelity models. This paper explores the ability to apply an adjustment factor to low fidelities models so as to scale them to high fidelity models. A response surface approximation of said adjustment factor is constructed using information of previous high and low fidelity simulations at corresponding design points using kriging. In doing so, finite difference estimations for sensitivities of a high fidelity model can be obtained using low fidelity models. It is shown that the error between predictions of a high fidelity model and low fidelity model decreases by applying an adjustment factor to the low fidelity model. Likewise, the error between the high fidelity and adjusted low fidelity model tends to decrease as more data is available for construction of the kriging model used to determine the adjustment factor.