Virtual RHI lidar scans retrieved in high-fidelity wake vortex simulations of landing aircraft under turbulent crosswind conditions - LES Lidar Simulator (LLS)

POS1_POS2_scans  = Individual scans of various simulations as well as background wind scans (no wake vortices).

(Note 0_0, 0_5, 1_0, 2_0 corresponds to the wind, same as POS1_POS2 below )

 

Scan naming convention: POS1_POS2_POS3_POS4_POS5_POS6_POS7.csv

 

Example: 0_5_D_248_8_161.2201878198302_168.4201878198237.csv

 

• POS1_POS2: Together they form a factor which is multiplied with the initial descend speed of the wake vortex pair, w_0. The definition for w_0 can be found in [3]. It is common for the crosswind speed to be set according to the multiples of w_0. Due to the landing of the A340 aircraft, and the logarithmic nature of the wind simulation, we set the crosswind at the b_0 altitude of the simulation. For a definition of b_0, also see [3]. For the above example, 0.5w_0 is the crosswind speed. Note that every 26 lidar positions (POS4), the direction of the crosswind changes, if there is a crosswind.

          - Crosswind approaches from port side: POS4: 0-25, 52-77, 104-129, 156-181, 208-233, 260-285

          - Crosswind approaches from starboard side: POS4: 26-51, 78-103, 130-155, 182-207, 234-259, 286-311

• POS3: Label indicating which part of the numerical simulation this scan belongs to (a full landing simulation consists of A-D). A: Hybrid RANS-LES, B,C,D: temporal LES (in order). For the above example, D indicates that the lidar scan was recorded during the last part of the simulation. W: Prior to the wake vortex simulations with crosswind, a background wind scan for each lidar position is recorded.

• POS4: Specifies the number of the lidar, implications are the longitudinal position along the glide path of the aircraft. In the packs of lidar positions described in the description of POS1_POS2, the last lidar position is the closest to the touchdown point of the aircraft, smaller lidar positions within this pack are further away (in order) - also see the lid_plane_info directory. Note that the lidar position also adjusts the spectrum of the elevation angles used (and thus the size of the lidar scan). For that see the associated virtual lidar scan raw data. In the above example we have lidar position 248, thus crosswind approaching from starboard and rather mid-way of the longitudinal glide path direction.

• POS5: Specifies the number of the scan for this lidar position (POS4) and simulation (POS1__POS2). In the above example this is scan number 8.

• POS6_POS7: Specifies the simulation time within which the scan was measured during the aircraft landing simulation (POS1__POS2). In the above example this is 161.2201878198302 s to 168.4201878198237 s.

The scans purely with wind, an no wake vortices are stored in an additional directory within conv_scans. The case '0_0' (no wind) does not require wind scans. 

 

Within the scan files, we have a four columns:

• t: Simulation time
• ELE: Elevation angle [deg] of the lidar beam
• R: Range from lidar [m]
• v_r: LOS velocity (radial velocity) of aerosols along lidar beam

 

wind_scans = Simulated lidar scans of the background wind with RWF.

Scans simulated here are in the same format as POS1_POS2_scans. Wind scans for the LLS scans without RWF application are found in naive_scan_subset - the scans with POS4 = 0 should be used here if more are available.

 

naive_scan_subset = Simulated lidar scans without RWF.

The format is the same as for POS1_POS2_scans, with the difference of being sorted first by wind subdirectories and then lidar number (LID).

 

labels = Labels of wake vortices for the above wake vortex scans. 

We have 4 main files, where each file represents the targets for one wind strength 0.0w_0, 0.5w_0, 1.0w_0, 2.0w_0.

Within the labels files, we have a multitude of columns with different data:

• #Time: Simulation (not scan) time.
• y_uw : lateral position in simulation domain of upwind (port) vortex.
• z_uw : height position in simulation domain of upwind (port) vortex.
• y_dw : lateral position in simulation domain of downwind (starboard) vortex.
• z_dw : height position in simulation domain of downwind (starboard) vortex.
• G_515_uw: Gamma 515 Circulation strength (see additional notes) of upwind (port) vortex [m^2/s].
• G_515_dw: Gamma 515 Circulation strength (see additional notes) of downwind (starboard) vortex [m^2/s].
• cr_uw: Core radius of upwind (port) vortex (in meters).
• cr_dw: Core radius of downwind (starboard) vortex (in meters).
• uw distance from lidar [m]: Horizontal distance of upwind (port) vortex from respective lidar.
• dw distance from lidar [m]: Horizontal distance of downwind (starboard) vortex from respective lidar.
• uw height [m]: Vertical distance of upwind (port) vortex from respective lidar (floor, as lidars are place at an altitude of 0 m).
• dw height [m]: Vertical distance of downwind (starboard) vortex from respective lidar (floor, as lidars are place at an altitude of 0 m).
• vortex age uw [s]: Age of upwind (port) vortex (after first generated by aircraft at respective measurement plane of lidar).
• vortex age dw [s]: Age of downwind (starboard) vortex (after first generated by aircraft at respective measurement plane of lidar).
• scan: Associated scan.
• LID: Associated lidar number.

On top of the summarizing files for each simulation, in the subdirectory individual, the label for each scan is given in a separate file.

The above gives information on the simulation truth, furthermore the file labels_with_rv.csv can be found here, where the following extra label columns are given for a subset of scans:

• wind: Strength of crosswind, same as POS1_POS2 in  POS1_POS2_scans. The sign corresponds to the wind direction. Negative is a crosswind from the port side of the aircraft, positive is a crosswind from the starboard side of the aircraft.
• Conv RV: 1 indicates the RV method has been evaluated for LLS scans with the RWF applied, 0 if not.
• Naive RV: 1 indicates the RV method has been evaluated for LLS scans without the RWF applied, 0 if not.
• conv rv G_515_uw: Gamma 515 Circulation strength (see additional notes) of upwind (port) vortex computed using the RV method on LLS scans with RWF applied  [m^2/s].
• conv rv G_515_dw: Gamma 515 Circulation strength (see additional notes) of downwind (starboard) vortex computed using the RV method on LLS scans with RWF applied [m^2/s].
• conv rv uw distance from lidar [m]: Horizontal distance of upwind (port) vortex from respective lidar using the RV method on LLS scans with RWF applied.
• conv rv dw distance from lidar [m]: Horizontal distance of downwind (starboard) vortex from respective lidar using the RV method on LLS scans with RWF applied.
• conv rv uw height [m]: Vertical distance of upwind (port) vortex from respective lidar (floor, as lidars are place at an altitude of 0 m) using the RV method on LLS scans with RWF applied.
• conv rv dw height [m]: Vertical distance of downwind (starboard) vortex from respective lidar (floor, as lidars are place at an altitude of 0 m) using the RV method on LLS scans with RWF applied.
• naive rv G_515_uw: Gamma 515 Circulation strength (see additional notes) of upwind (port) vortex computed using the RV method on LLS scans without RWF applied [m^2/s].
• naive rv G_515_dw: Gamma 515 Circulation strength (see additional notes) of downwind (starboard) vortex computed using the RV method on LLS scans without RWF applied [m^2/s].
• naive rv uw distance from lidar [m]: Horizontal distance of upwind (port) vortex from respective lidar using the RV method on LLS scans without RWF applied.
• naive rv dw distance from lidar [m]: Horizontal distance of downwind (starboard) vortex from respective lidar using the RV method on LLS scans without RWF applied.
• naive rv uw height [m]: Vertical distance of upwind (port) vortex from respective lidar (floor, as lidars are place at an altitude of 0 m) using the RV method on LLS scans without RWF applied.
• naive rv dw height [m]: Vertical distance of downwind (starboard) vortex from respective lidar (floor, as lidars are place at an altitude of 0 m) using the RV method on LLS scans without RWF applied.
• uw phi [deg]: Elevation angle to the center of the upwind (port) vortex from the simulation truth.
• uw range [m]: Range from the lidar to the center of the upwind (port) vortex from the simulation truth.
• dw phi [deg]: Elevation angle to the center of the downwind (starboard) vortex from the simulation truth.
• dw range [m]: Range from the lidar to the center of the downwind (starboard) vortex from the simulation truth.
• conv rv uw phi [deg]: Elevation angle to the center of the upwind (port) vortex using the RV method on LLS scans with RWF applied.
• conv rv uw range [m]: Range from the lidar to the center of the upwind (port) vortex using the RV method on LLS scans with RWF applied.
• conv rv dw phi [deg]: Elevation angle to the center of the downwind (starboard) vortex using the RV method on LLS scans with RWF applied.
• conv rv dw range [m]: Range from the lidar to the center of the downwind (starboard) vortex using the RV method on LLS scans with RWF applied.
• naive rv uw phi [deg]: Elevation angle to the center of the upwind (port) vortex using the RV method on LLS scans without RWF applied.
• naive rv uw range [m]: Range from the lidar to the center of the upwind (port) vortex using the RV method on LLS scans without RWF applied.
• naive rv dw phi [deg]: Elevation angle to the center of the downwind (starboard) vortex using the RV method on LLS scans without RWF applied.
• naive rv dw range [m]: Range from the lidar to the center of the downwind (starboard) vortex using the RV method on LLS scans without RWF applied.
• y err conv uw [m]: Cartesian localization error (RV minus ST) in y-direction (lateral) between simulation truth and RV method of upwind (port) vortex center on LLS scans with RWF applied.
• y err conv dw [m]: Cartesian localization error (RV minus ST) in y-direction (lateral) between simulation truth and RV method of downwind (starboard) vortex center on LLS scans with RWF applied.
• z err conv uw [m]: Cartesian localization error (RV minus ST) in z-direction (vertical) between simulation truth and RV method of upwind (port) vortex center on LLS scans with RWF applied.
• z err conv dw [m]: Cartesian localization error (RV minus ST) in z-direction (vertical) between simulation truth and RV method of downwind (starboard) vortex center on LLS scans with RWF applied.
• y err naive uw [m]: Cartesian localization error (RV minus ST) in y-direction (lateral) between simulation truth and RV method of upwind (port) vortex center on LLS scans without RWF applied.
• y err naive dw [m]: Cartesian localization error (RV minus ST) in y-direction (lateral) between simulation truth and RV method of downwind (starboard) vortex center on LLS scans without RWF applied.
• z err naive uw [m]: Cartesian localization error (RV minus ST) in z-direction (vertical) between simulation truth and RV method of upwind (port) vortex center on LLS scans without RWF applied.
• z err naive dw [m]: Cartesian localization error (RV minus ST) in z-direction (vertical) between simulation truth and RV method of downwind (starboard) vortex center on LLS scans without RWF applied.
• D err conv uw [m]: Two-norm error for the Cartesian coordinates to the vortex center between simulation truth and RV method of upwind (port) vortex center on LLS scans with RWF applied.
• D err conv dw [m]: Two-norm for the Cartesian coordinates to the vortex center between simulation truth and RV method of downwind (starboard) vortex center on LLS scans with RWF applied.
• D err naive uw [m]: Two-norm error for the Cartesian coordinates to the vortex center between simulation truth and RV method of upwind (port) vortex center on LLS scans without RWF applied.
• D err naive dw [m]: Two-norm for the Cartesian coordinates to the vortex center between simulation truth and RV method of downwind (starboard) vortex center on LLS scans without RWF applied.
• plus_minus_phi: Indicates whether a RHI lidar scan features a positive lidar scanning rate (plus), or a negative one (negative).
• conv err G_515_uw: Circulation error (RV minus ST) between simulation truth and RV method of upwind (port) on LLS scans with RWF applied [m^2/s]. 
• conv err G_515_dw: Circulation error (RV minus ST) between simulation truth and RV method of downwind (starboard) on LLS scans with RWF applied [m^2/s]. 
• naive err G_515_uw: Circulation error (RV minus ST) between simulation truth and RV method of upwind (port) on LLS scans without RWF applied [m^2/s]. 
• naive err G_515_dw: Circulation error (RV minus ST) between simulation truth and RV method of downwind (starboard) on LLS scans without RWF applied [m^2/s]. 
• conv err uw phi: Elevation angle error (RV minus ST) between simulation truth and RV method of upwind (port) vortex center on LLS scans with RWF applied [deg].
• conv err dw phi: Elevation angle error (RV minus ST) between simulation truth and RV method of downwind (starboard) vortex center on LLS scans with RWF applied [deg].
• naive err uw phi: Elevation angle error (RV minus ST) between simulation truth and RV method of upwind (port) vortex center on LLS scans without RWF applied [deg].
• naive err dw phi: Elevation angle error (RV minus ST) between simulation truth and RV method of downwind (starboard) vortex center on LLS scans without RWF applied [deg].
• conv err uw range: Range from lidar error (RV minus ST) between simulation truth and RV method of upwind (port) vortex center on LLS scans with RWF applied [m].
• conv err dw range: Range from lidar error (RV minus ST) between simulation truth and RV method of downwind (starboard) vortex center on LLS scans with RWF applied [m].
• naive err uw range: Range from lidar error (RV minus ST) between simulation truth and RV method of upwind (port) vortex center on LLS scans without RWF applied [m].
• naive err dw range: Range from lidar error (RV minus ST) between simulation truth and RV method of downwind (starboard) vortex center on LLS scans without RWF applied [m].

0_0_movement.csv gives insight on the vertical movement on selected vortices in selected lidar scans of the 0_0 wind case. 

The following data columns exist within the file (note csv file with ; separator):

• Str_dw: Vertical movement of the downwind (starboard) vortex, 0 is neutral, -1 is downward, and 1 is upward.
• Prt_uw: Vertical movement of the upwind (port) vortex, 0 is neutral, -1 is downward, and 1 is upward.
• scan_code: Identfies associated lidar scan with POS3_POS4_POS5 as in POS1_POS2_scans.

 

lid_plane_info = Additional guidance on the simulated lidars.

Each simulation case has a separate file due to minimal ground speed changes of the aircraft. 

The following data columns exist within each file:

• Index: Gives the lidar number corresponding to POS4 and LID.
• Plane Pos [x]: Gives the longitudinal position of the lidar with respect to the glide path of the aircraft in meters.
• time plane passed [s]: Gives the simulation time when the aircraft first passes the measurement plane (related to the previous column.
• height plane passed [m]: Aircraft altitude at the respective lidar positon.
• lateral position lidar from GP [m]: Lateral position of the lidar from the glide path of the aircraft.

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• Gamma 515 circulation [3]: The Gamma 515 circulation is the averaged circulation of a vortex evaluated at radii 5-15m from the vortex center. 

Funding: This dataset was generated within the mFUND KIWI project funded by the Federal Ministry for Digital and Transportation Germany and the DLR undertaking "Wetter und Disruptive Ereignisse".

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Acknowledgements:

The necessary RANS simulations were performed as part of the EU-funded AWIATOR by DLR's Institute of Aerodynamics and Flow Technology.

We acknowledge Airbus for the allowance to use the RANS data.

The LES was performed with the incompressible Navier-Stokes code MGLET [4] and kindly provided by the Technical University of Munich, Hydromechanics.

The wake vortex simulations were computed on the high performance computer SuperMUC-NG by Leibniz-Rechenzentrum (LRZ).

 

References: 

 

[1] Smalikho, Igor., et al. "Method of radial velocities for the estimation of aircraft wake vortex parameters from data measured by coherent Doppler lidar." Optics Express      23.19 (2015): A1194-A1207.

 

[2] Robey, Rachel, and Julie K. Lundquist. "Behavior and mechanisms of Doppler wind lidar error in varying stability regimes." Atmospheric Measurement Techniques 15.15 (2022): 4585-4622.

 

[3] Gerz, Thomas, Frank Holzäpfel, and Denis Darracq. "Commercial aircraft wake vortices." Progress in Aerospace Sciences 38.3 (2002): 181-208. 

 

[4] Manhart, Michael. "A zonal grid algorithm for DNS of turbulent boundary layers." Computers & fluids 33.3 (2004): 435-461.