Characterization and optimal design of measurements in transitional high-speed flows
Abstract
Detailed simulations of transitional hypersonic flows can provide a detailed description of transition mechanisms. The simulations,however, introduce consequential assumptions in particular regarding the flow environment which has significant impact on the transition process. Physical measurements have therefore remained the highest fidelity record of hypersonic flow, even if measurements inthis regime are sparse, in particular during flight tests. Due to the flow sensitivity to uncertainty and the sparsity of measurements, crucial flow events can easily evade detection. As such, the deployment of each sensor must maximize its utility, which can be achieved using data assimilation techniques. Rather than view the sensor signal as a mere record of the measured quantity, data assimilation uses the sensor data to minimize uncertainty in numerical simulations such that the computations reproduce the measurements. The fidelity of the simulation is thus enhanced, and the measurements are augmented with computational predictions at full spatio-temporal resolution. In this context, the optimal design of experimental measurements is one that minimizes the uncertainty of the solution to the data-assimilation problem. In other words, the design of measurements enables the most accurate estimation of the flow, once the sensor data are infused in the computation. Achieving this goal must take into account the type of measurement and the sensor placement. Adjoint-variational techniques are adopted to precisely quantify the capacity of a sensor to detect flow events that precede the measurement. This approach enables a quantitative comparison of different sensor modalities and placements in transitional flows. The impact of qualitative changes in the flow will be evaluated including the interaction of shocks with boundary layersand flow separation. Optimal designs will be sought that maximize the observability of a network of sensors, where they can collectively observe different disturbances modes, either propagating within the boundary layer or incident from the free stream. In addition to adopting high-fidelity computational techniques for optimal design of measurements, we will seek the development of simplifiedmodels that can be adopted widely and efficiently.Approved for public release
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 12, 2025
- Source ID
- N000142512170
Entities
People
- Tamer A. Zaki
Organizations
- Johns Hopkins University
- Office of Naval Research
- United States Navy