Effective adjoint approaches for computational fluid dynamics

A Jacobian-free approximate Newton–Krylov startup strategy for RANS simulations

Robust aerodynamic shape optimization—From a circle to an airfoil

Computational fluid dynamics through the solution of the Navier–Stokes equations with turbulence models has become commonplace. However, simply solving these equations is not sufficient to be able ...

ADflow: An Open-Source Computational Fluid Dynamics Solver for Aerodynamic and Multidisciplinary Optimization

Surrogate-based optimization has been used in aerodynamic shape optimization, but it has been limited due to the curse of dimensionality. Although a large number of variables are required for the s...

Efficient Aerodynamic Shape Optimization with Deep-Learning-Based Geometric Filtering

Boundary layer ingestion (BLI) is a technology where the main propulsion system or an auxiliary fan is used to ingest the wake generated by the aircraft to improve aeropropulsive performance. The STARC–ABL concept introduced by NASA uses this technology with a traditional tube and wing configuration. Even though the concept is similar to conventional aircraft, design intuition is heavily limited due to the lack of previous experience with BLI. To achieve energy savings through BLI, multidisciplinary analysis and optimization tools that consider the fully coupled aeropropulsive design are required. In this work, we optimize the BLI system design of the STARC–ABL configuration at a number of net force and fan pressure ratio (FPR) values using a coupled aeropropulsive approach. The optimized designs demonstrate the increase in shaft power requirement for the BLI fan with increasing FPR values. We show that the power requirement is more sensitive to the thrust required from the BLI system, while the stagnation pressure distribution at the wake is more sensitive to FPR.

Aeropropulsive Design Optimization of a Boundary Layer Ingestion System

Boundary-layer ingestion (BLI) offers the potential for significant fuel burn reduction by exploiting tightly coupled aeropropulsive effects. NASA’s Single-aisle Turboelectric Aircraft with Aft Boundary-Layer propulsion (STARC-ABL) concept employs BLI on an electrically powered tail cone thruster to take advantage of the technology on what is otherwise a conventional airframe. Despite the traditional airframe of this concept, aeropropulsive integration is critical to the BLI propulsor’s performance. Therefore, it is vital to employ tightly coupled aeropropulsive models to design BLI systems. In this work, 3-D RANS simulations are used to model the aerodynamics, and 1-D thermodynamic cycle analyses are used to model the propulsion system. The two models are tightly coupled using NASA’s OpenMDAO framework, enabling efficient design optimization through gradient-based optimization with analytic derivatives. Using this coupled aeropropulsive framework, 18 computational fluid dynamics (CFD)-based aeropropulsive design optimizations are performed to study the power requirements of the BLI configuration and a reference podded configuration where the electric fan ingests freestream air. This study provides the first set of CFD-based performance data for the STARC-ABL concept across the design space of BLI fan size and pressure ratio. The results quantify the power savings through BLI compared to a traditional propulsion system. 

Anil Yildirim

Papers

A Jacobian-free approximate Newton–Krylov startup strategy for RANS simulations

Robust aerodynamic shape optimization—From a circle to an airfoil

ADflow: An Open-Source Computational Fluid Dynamics Solver for Aerodynamic and Multidisciplinary Optimization

Aeropropulsive Design Optimization of a Boundary Layer Ingestion System

Boundary-Layer Ingestion Benefit for the STARC-ABL Concept