A novel framework to assess the wake vortex hazards risk supported by aircraft in en-route operations

The work presented in this paper was partially funded by the SESAR Joint Undertaking under grant agreement No 699247, as part of the European Union’s Horizon 2020 research and innovation programme: R-WAKE project (Wake Vortex Simulation and Analysis to Enhance En-route Separation Management in Europe - http://www.rwake-sesar2020.eu/). TThis paper presents the simulation environment developed within the framework of R-WAKE project, funded by SESAR 2020 Exploratory Research. This project aims to investigate the risks and hazards of potential wake vortex encounters in the en-route airspace, under current and futuristic operational scenarios, in order to support new separation standards aimed at increasing airspace capacity. The R-WAKE simulation environment integrates different components developed by different partners of the R-WAKE consortium, including simulators for weather, traffic, wake vortex phenomena, wake vortex interactions and different tools and methodologies for safety and risk assessment. A preliminary example is presented in this paper, in which 200 historical trajectories were simulated to show that the novel framework works properly. A WVE encounter has been detected in such first scenario, however with no significant safety effect on the follower aircraft. A second controlled scenario has been then run to force the detection of a severe wake encounter under realistic en-route conditions. Such scenario has given evidences that confirm the safety relevance of the underlying research concept.Peer ReviewedPostprint (published version

An Aeroelastic Flight Dynamics Model for Gust Load Alleviation of Energy-Efficient Passenger Airplanes

Gust load alleviation (GLA) can reduce the maximum loads encountered by airplanes, allowing the structure to be designed lighter, thus saving fuel. Active GLA therefore represents an important subarea in the research of energy-efficient passenger airplanes. However, from a flight dynamics perspective, there are no publicly available simulation environments that allow for an efficient and modular investigation of different technologies like novel GLA controllers or novel flow actuators. Therefore, this paper presents such a simulation environment. The presented aeroelastic flight dynamics model is based on indicial functions combined with a dynamic stall model to predict the unsteady aerodynamics similar to a strip theory approach, while the downwash is considered using a nonlinear steady lifting line method. The structural dynamics are based on the mode displacement method and coupled with the aerodynamics model using constant transformation matrices as well as nonlinear transformations for the inflow. A comparison of the presented model with unsteady Reynolds-Averaged Navier--Stokes simulations shows good agreement for a selected gust case. The presented simulation model is parameterized as an energy-efficient passenger airplane with a light-weight wing sizing by reducing the limit loads from 2.5\,g to 2.0\,g for equivalent pull-up maneuvers. Open-loop gust load envelopes are presented and discussed for the energy-efficient airplane with different model settings, e.g. with and without dynamic stall model. The source code of the simulation modules is available at: https://github.com/iff-gsc/se2a_aviation_2023. A video of the flight simulation is available at: https://youtu.be/cO5q06Qkkg

Aircraft Wake-Vortex Evolution in Ground Proximity: Analysis and Parameterization

Field measurement data of 282 wake vortex pairs and respective environmental conditions acquired at Frankfurt Airport by means of lidar, Sodar/RASS, and ultrasonic anemometer are used to analyze wake vortex behavior in ground proximity. Exceptional cases with strong rebounds caused by detached shear layers and obstacles are introduced and estimates of the time needed to clear the runway from wake vortices by advection are provided. The impact of turbulence and crosswind on wake vortex decay proves to be weak, whereas already light crosswind turns out to be sufficient to cause pronounced asymmetric rebound characteristics. Based on the analyses vortex decay and rebound characteristics are parameterized and implemented into the probabilistic two-phase aircraft wake-vortex model. Deterministic and probabilistic prediction skill of the enhanced vortex model are assessed. Comparison to wake predictions out of ground effect indicates that in ground effect (i) the rapid-decay phase progresses slower, (ii) wake vortex evolution can be predicted with improved accuracy, and (iii) fair prediction skill requires only limited environmental data

Analyse und Parametrisierung des Wirbelschleppenverhaltens in Bodennähe

Von August bis Dezember 2004 wurde am Frankfurter Rhein-Main-Flughafen eine Messkampagne durchgeführt, bei der Wirbelschleppen mit Hilfe eines Lidars (LIght Detection And Ranging) und Umgebungsvariablen der Atmosphäre durch ein Sodar-RASS (SOund Detection And Ranging; Radio Acoustic Sounding System) und ein Ultraschallanemometer vermessen wurden. Ein Ziel der Kampagne bestand in der Untersuchung des Zerfalls und des Transportes von Wirbelschleppen in Bodennähe. In der vorliegenden Arbeit wird der derzeitige Stand des Wissens in Bezug auf den Bodeneinfluss auf Wirbelschleppen beschrieben. Die erfassten Messdaten werden entsprechend graphisch und statistisch aufbereitet, beurteilt und mit dem Bodenzerfallsmodell von Proctor und Hamilton verglichen. Basierend auf dem P2P-Modell (Probabilistic Two-Phase Wake Vortex Decay and Transport Model) des Institutes für Physik der Atmosphäre am Deutschen Zentrum für Luft- und Raumfahrt in Oberpfaffenhofen wird eine Parametrisierung für den Bodenzerfall ermittelt. Das gefundene Modell wird direkt mit den Messdaten verglichen und statistisch über Wahrscheinlichkeitsdichteverteilungen beurteilt. Die gefundene Parametrisierung wird zudem mit dem Wirbelschleppenmodell der NASA verglichen

Aircraft Wake-Vortex Evolution in Ground Proximity: Analysis and Parameterization

Field measurement data of 282 wake vortex pairs and respective environmental conditions acquired at Frankfurt Airport by means of lidar, Sodar/RASS, and ultrasonic anemometer are used to analyze wake vortex behavior in ground proximity. The impact of turbulence and crosswind on wake vortex decay proves to be weak, whereas already light crosswind turns out to be sufficient to cause pronounced asymmetric rebound characteristics. Particular cases with strong rebounds caused by detached shear layers and obstacles are discussed. Estimates of the time needed to clear the runway from wake vortices by advection are provided. Vortex decay and rebound characteristics are parameterized and implemented into the probabilistic two-phase aircraft wake-vortex model (P2P). Deterministic and probabilistic prediction skill of P2P are assessed. Comparison to wake predictions out of ground effect indicates that in ground effect (i) the rapid-decay phase progresses slower, (ii) wake vortex evolution can be predicted with improved accuracy, and (iii) fair prediction skill requires only limited environmental data

Aviation Applications: Hybrid Navigation Techniques and Safety-of-Life Requirements, Part 1

This paper describes some key results of the UniTaS IV project, a publicly funded effort to investigate special problems in the application of satellite navigation for aviation. Among the subjects covered: adaptive beamforming antennas, a GNSS landing system that incorporates inertial sensors with a ground-based augmentation system (GBAS), multiconstellation RAIM (receiver autonomous integrity monitoring), and jamming, spoofing, and authentication of signals

Understanding the Flight Mechanics of Active High-Lift Aircraft Configurations: Achievements of the CRC 880 Project

Flight mechanics of short take-off and landing aircraft with active high-lift system and propeller engines exhibit excellent low airspeed flight performance on the one hand but also flight mechanical challenges on the other. These are results of previous work of the 60s as well as of the Collaborative Research Centre CRC 880. In the CRC 880 project, new knowledge about unsatisfactory handling qualities was gained by flight dynamics modeling and simulations based on a high-fidelity computational fluid dynamics database of the CRC reference aircraft. This paper summarizes the results of the flight dynamics that confirm excellent flight performance, minor challenges in the longitudinal motion and major challenges in the lateral-directional motion. Passive and active countermeasures are discussed to improve the handling qualities. Moreover, it is shown that only partial failures of the active high-lift system can be compensated. Finally, the paper gives an outlook on future work

Controllability of an Aircraft with Active High-Lift System using a Segmentwise Controllable Flap System

Active high-lift aircraft need exceptional aerodynamic control performance to operate at low airspeed. In this study a new concept for the improvement of controllability is investigated, incorporating the special capabilities of a blown Coanda flap system. The blowing system along the flaps is divided into twelve independently controllable segments. This provides the opportunity to influence the lift distribution along the wingspan by individual blowing performance settings for each segment without changing the flap deflection. This offers the chance to control the airplane in the final approach phase with fully deflected flaps by using only the blowing system and to dedicate specific control tasks to particular segments. A model for the blowing system influence on the local wing aerodynamics is implemented in an existing nonlinear full aircraft flight mechanics model. The system capabilities in terms of roll control and the climb performance are investigated by criteria evaluation and dynamic simulation assessment. The ability to fly turn/altitude change maneuvers by utilizing the active high-lift system is proven and a corresponding control concept is presented. It also includes the compensation of different blowing failure cases, which leads to acceptable but still improvable aircraft reactions

R-WAKE - Simulations Results Database and Concept Development

This REPORT is part of a project that has received funding from the SESAR Joint Undertaking under grant agreement No 699247 under European Union’s Horizon 2020 research and innovation programme.This report presents the deliverable D5.1 “Simulations Results Database and Separation ConceptDevelopment” of the R-WAKE project. This D5.1 report has two main parts. The 1 st part describes the meaning and purpose of the database generated using the R-WAKE System simulations tools and used in the WV-Encounters Hazard Study. This part of report, together with the associated package of database files that contain the simulation results, constitutes the third expected tangible outcome of the project (O3): “Database of simulation results that will provide enough evidence to propose new Separation Schemes for further R&I activities”. The 2 nd part of the report provides the discussion and elaboration of a set of proposals for Separation Scheme improvements in En-Route operations, based on the body of evidence available in the generated simulation data. That is, the R-WAKE Concept Development. This part represents the central subject for the Safety and Robustness Analysis project tasks 5.2, reported in deliverable D5.2. D5.1 part2 together with D5.2 constitutes the fourth expected tangible outcome of the project (O4): “Evidence-based proposal for either maintaining current Separation Standards or adopting new ones”. The R-WAKE project addresses the SESAR 2020 Exploratory Research work-programme topic ER-07- 2015 - Separation Management and Separation Standards, within the area of Advanced Air Traffic Services (ATS). The R-WAKE project overall objective is to investigate the risks and hazards of potential wake vortex encounters in the en-route airspace, in order to assess potential enhancements for the Separation Standards and Separation Management methods in Europe