Rotorcraft Downwash Recirculation Modeling Near Obstacles
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current flight simulators struggle to accurately simulate the recirculation effects of a helicopter's main rotor downwash interacting with nearby obstacles, which can lead to reduced performance and un-commanded pitch and bank changes due to the dynamic nature of these interactions, which are not captured by static computational fluid dynamics solutions.
Innovation Solution
A computer-implemented method and system that determines the recirculation induced airflow velocity by generating a line of sight vector, calculating the distance between the simulated rotorcraft and obstacles, and using aircraft airspeed and height to calculate the recirculation induced airflow velocity, allowing for real-time simulation of these effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If static CFD solutions are used to pre-calculate flow fields around structures, then manufacturing precision of the simulation model is improved, but the simulation cannot capture dynamic recirculation effects and becomes unreliable for real-time training
Solution Approach 1:
The patent transitions from static CFD solutions to a dynamic real-time calculation method that computes recirculation effects based on current helicopter position, airspeed, and obstacle geometry. The system calculates induced velocity fields and recirculation factors dynamically during simulation runtime, allowing the model to adapt to changing flight conditions and accurately capture recirculation phenomena that static solutions cannot represent.
2Reliability
If real-time dynamic simulation of recirculation effects is implemented, then reliability of training simulation is improved, but computational complexity and processing requirements increase
Solution Approach 1:
The patent replaces complex full-field CFD computations with a simplified analytical model that calculates recirculation effects using closed-form equations. The system uses geometric relationships between helicopter position and obstacles, combined with pre-defined induced velocity profiles, to compute recirculation factors in real-time without requiring iterative numerical solutions, thereby reducing computational complexity while maintaining accuracy.
Solution Approach 2:
The patent changes the approach from solving complete flow fields to computing only the critical recirculation parameters (induced velocity, recirculation factor) based on simplified geometric and kinematic parameters. By focusing on the essential parameters that govern recirculation effects and using efficient calculation methods, the system achieves real-time performance with reduced computational burden.
3Measurement precision
If comprehensive CFD simulations are performed to capture all flight conditions, then measurement precision of flow fields is improved, but loss of time for computation and simulation setup increases
Solution Approach 1:
The patent performs preliminary calculations of induced velocity fields and recirculation characteristics during system initialization or offline preparation. These pre-computed parameters are then reused and adjusted in real-time based on current flight conditions, avoiding the need to perform complete CFD simulations during runtime. This approach maintains flow field accuracy while dramatically reducing computation time during actual training simulations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides a more realistic training simulation by accurately modeling the recirculation effects of the main rotor downwash, improving the simulation fidelity and reducing adverse interactions with obstacles, thereby enhancing pilot training without the costs associated with traditional CFD methods.
Implementation Method 1
the main rotor downwash that consists of a downward airflow that can interact with the ground and surrounding obstructions... the recirculation induced airflow velocity being caused by a downwash recirculation flow generated by the simulated obstacle
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method (30) for determining an effect of a simulated obstacle (84) on a main rotor induced velocity of a simulated rotorcraft (82) in a simulation, comprising: receiving an aircraft airspeed of the simulated rotorcraft (82) and a height above ground for the simulated rotorcraft (32); generating a line of sight vector having a source position located on the simulated rotorcraft, a direction and a given length (34); determining a distance between the simulated obstacle (84) and the simulated rotorcraft (82) using the line of sight vector (36), the distance being at most equal to the given length of the line of sight vector; determining an induced airflow velocity using the distance between the simulated obstacle and the simulated rotorcraft (82), the aircraft airspeed and the height above ground (38), the induced airflow velocity being caused by a downwash recirculation flow generated by the simulated obstacle; and outputting the induced airflow velocity (40).