Engineering topics

Witold J F Koning

Publications and source records attributed to Witold J F Koning.

6 records

NASA NTRS2024

Mars Science Helicopter Rotor Geometry

The Jet Propulsion Laboratory and NASA Ames Research Center are exploring possibilities for a Mars Science Helicopter (MSH), a second-generation Mars rotorcraft designed to conduct science investigations independently of a lander or rover. The goal of the MSH concept design is to establish the feasibility of flying a larger, more capable rotorcraft on Mars, with a payload of two to three kg and an overall vehicle mass of approximately twenty kg. This report documents the geometry (including planform, twist, and airfoils) of the MSH (hexacopter configuration) rotor, for use in future research on rotor performance in the Mars atmosphere.

Mars↗

NASA NTRS2024

Experimental Results for Mars Rotorcraft Airfoils (roamx-0201 and clf5605) at Low Reynolds Number and Compressible Flow in a Mars Wind Tunnel

Experimental results are obtained for a roamx-0201 type airfoil and the clf5605 airfoil at highsubsonic, low Reynolds number conditions using the Tohoku University Mars Wind Tunnel, Japan. The tests are conducted at a Mach number of M = 0.60, and a Reynolds number of Re = 20,000 to reflect representative aerodynamics of a rotor blade for Mars exploration. The angle of attack is varied between α = −2.0 deg and α = 6.0 deg. The roamx-0201 type airfoil is an unconventional airfoil optimized for the chosen tunnel operating conditions using the Evolutionary aLgorithm for Iterative Studies of Aeromechanics (ELISA), developed under the Rotor Optimization for the Advancement of Mars eXploration (ROAMX) project. ELISA is utilized here to optimize aerodynamic airfoil performance using a Genetic Algorithm and two-dimensional high-fidelity CFD simulations, ultimately resulting in a Pareto-optimal airfoil set. The clf5605 airfoil is the outboard airfoil used on the Ingenuity Mars Helicopter and provides a baseline against which the roamx-0201, as well as possible future airfoil profiles for the compressible low Reynolds number regime, can be compared against. Lift and drag data are recorded using a balance, pressure distributions are obtained using Pressure Sensitive Paint (PSP) application, and Schlieren images are obtained to visualize the flowfield. The data is tabulated to aid future research.

Roamx↗

NASA NTRS2024

Mars Helicopter Ingenuity Rotor Geometry

The NASA Mars Helicopter Ingenuity performed its maiden flight on April 19, 2021, and opened new possibilities for planetary exploration. Ingenuity has ended its mission after experiencing an anomaly during its 72nd flight on January 18, 2024. Due to the low density and low temperature of the surface atmosphere on Mars, significant challenges must be overcome to achieve aerodynamic performance. The low density of the Martian atmosphere and the relatively small-scale rotor result in flows with very low Reynolds number, reducing the lifting force and lifting efficiency, respectively. Until recently, compressible flow at Reynolds numbers around Re = 10,000 was of moderate practical interest but with the success of Ingenuity, the aerodynamic regime is appreciating considerable attention. The purpose of this report is to document the geometry (planform, twist, and airfoils) of the Mars Helicopter rotor, for use in future research on rotor performance in the Mars atmosphere.

Mars↗

NASA NTRS2022

Preliminary Airfoil Design for Low Reynolds Numbers

Advances in the fields of electronics, batteries, and electric motors have enabled broad adoption of small-scale aircraft for various terrestrial applications. Numerous Micro Aerial Vehicles (MAVs) and small Unmanned Aerial Vehicles (UAVs), both civil and military, are in use today. Operation at their design flight condition often requires rotors, propellers, or wings to perform at Reynolds numbers significantly below 500,000 [1]. Airfoil performance at low Reynolds numbers is generally characterized by low aerodynamic performance (i.e. the attainable lift-to-drag ratio) compared to performance of airfoils at higher Reynolds numbers. The critical chord-based Reynolds number for conventional airfoils lies around Rec = 100,000 to Rec = 500,000 [2]. Below this critical Reynolds number, laminar separation of the boundary layer is usually the cause for poor performance. Researchers have found that below the critical Reynolds number, flat and cambered plates can outperform smooth airfoils. Circular-arc cambered plates especially have remarkable performance advantages compared to conventional airfoil shapes [3].

airfoil↗

NASA NTRSDate not supplied

Predicted Performance Effects of Blade Elasticity on Testing of Rotors for Mars

The Rotor Optimization for the Advancement of Mars Exploration project (ROAMX) has designed and manufactured a set of rotor blades optimized for hover on Mars. These blades will soon be tested for hover performance in the NASA Ames Research Center Planetary Aeolian Laboratory, a large vacuum chamber capable of rotor testing at reduced pressures. To match the tip Mach numbers during this testing with the tip Mach numbers that would be experienced in the Martian atmosphere, the rotor will be spun faster in the vacuum chamber than it would be spun on Mars. While this accomplishes the goal of simulating the tip Mach numbers of Mars operations, the elevated RPM may have undesired consequences for performance, due to elastic deflections of the blades. The purpose of this paper is to use CAMRAD II, a rotorcraft comprehensive analysis code, to predict the effect on performance of blade elasticity at elevated RPM in the vacuum chamber environment. Results are presented for different thrust conditions and different rotor speeds, and comparisons are made between rigid and elastic blade predictions. Overall, the CAMRAD II analysis suggests that blade elasticity does influence rotor performance in the operating conditions of interest, although the effect is moderate enough to conclude that the PAL testing will be a good simulation of Mars operation.

Blade elasticity↗

NASA NTRSDate not supplied

ELISA: A Tool for Optimization of Rotor Hover Performance at Low Reynolds Number in the Mars Atmosphere

The Evolutionary aLgorithm for Iterative Studies of Aeromechanics (ELISA) was developed in support of the Rotorcraft Optimization for the Advancement of Mars eXploration (ROAMX) project. ELISA was developed to enable aerodynamic rotor hover optimization for low Reynolds number flows in the Mars atmosphere. The first objective of the algorithm allows for unconventional airfoil parameterization and multi-objective airfoil geometry optimization using OVERFLOW. The Pareto-optimal airfoil sets are converted to a set of Pareto-optimal airfoil decks, providing the lowest drag air foil geometry for each angle of attack, removing the need to arbitrarily select the airfoils to be used in the rotor optimization. The second objective allows for rotor geometry optimization with simultaneous maximization of blade loading and minimization of rotor power using the comprehensive analysis CAMRADII. The result is a Pareto-optimal rotor set, providing the lowest power rotor for each attainable blade loading, and one of the first tools for hover-optimized rotors for high-subsonic low Reynolds number conditions. The airfoil thickness can be modified after the airfoil optimization is complete, allowing for a post-airfoil-optimization adjustment of blade thickness to facilitate conforming to external structural analyses requirements. The relevance of the code is demonstrated with case studies for the ROAMX rotor optimization for Ingenuity-sized single rotors in the Mars atmosphere, a performance study optimizing the chord and twist of Ingenuity’s coaxial rotor resulting in the Sample Recovery Helicopters candidate rotor, and high-subsonic low Reynolds number airfoil optimization providing novel insights for higher-efficiency low Reynolds number airfoil geometries and flow physics.

ELISA↗