Propeller design is a complex task that involves a variety of disciplines such as: aerodynamics, structural analysis, and acoustics. A new method of designing an optimal propeller which is based on a MDO (Multidisciplinary Design Optimization) approach is presented. By combining various analysis tools with an optimization tool, a powerful and flexible design method is obtained. During the design process three different optimization schemes are used, leading the design to its optimal goal. This new method is applied for the design of a propeller for an Ultralight aircraft. Several optional designs for different design goals are presented. The results of the new method are compared with results of the classical design method, based on Betz's condition, which considers only the aerodynamic performance of the propeller. The importance of addressing the characteristics of the entire air-vehicle, its aerodynamic characteristics and its propulsion system (engine, gear box, etc.), rather than only the isolated propeller, is emphasized.

Optimization of Propeller Based Propulsion System

Propellers used for electric vertical takeoff and landing (eVTOL) aircraft propulsion systems experience a wide range of aerodynamic conditions, including large incidence angles relative to oncomin...

System Identification for Propellers at High Incidence Angles

Propellers used for electric vertical takeoff and landing (eVTOL) aircraft propulsion systems experience a wide range of aerodynamic conditions, including large incidence angles relative to oncoming airflow. In oblique flow, propellers exhibit deviations in thrust and torque oriented along the propeller axis of rotation, as well as significant off-axis forces and moments. Although important for modeling eVTOL aircraft aerodynamics, sparse experimental data or mathematical models exist for propellers at incidence. This paper describes a propulsion system modeling methodology for the Langley Aerodrome No. 8 (LA-8) tandem tilt-wing, eVTOL aircraft. System identification methods are applied to isolated propeller wind tunnel data gathered across the vehicle's flight envelope to develop a mathematical model of the propulsion system, including a static motor model, dynamic motor model, and propeller aerodynamic model. Modeling results validated against data withheld from the modeling process indicate good predictive capability and agree with theoretical expectations. The results are followed by a discussion of model implementation strategies into high-fidelity eVTOL aircraft simulations.

/pdf/system-identification-for-propellers-at-high-incidence-4to8x88dtt.pdf

We revisit a 1950s era wind tunnel test of a wing-propeller combination and present an approximate analytic model of the lift and drag forces generated by a wing completely immersed in the slipstream of the propellers for a range of angles of attack from 0-90°. We compare the analytic model to the experimental results by recreating the experiment in simulation. We then use the aerodynamic model along with an appropriate propeller thrust model to demonstrate how the Projection Operator Newton method for Trajectory Optimization, PRONTO, can be used to map curves specified on the equilibrium manifold to the space of trajectories of a flying wing model.

Transition to Hover for a Flying Wing with Electric Propulsion

Transition Trajectory Optimization for a Tiltwing VTOL Aircraft with Leading-Edge Fluid Injection Active Flow Control

Analytical and experimental studies have been undertaken on propellers operating in the unsteady flow field produced by interaction effects due to the fuselage, wing, and nacelles Methods have been developed and verified experimentally for determining the velocity field in which a propeller operates as well as its aerodynamic and dynamic response to this unsteady environment Methods are presented for predicting the net thrust of a propeller-wing-body combination as well as the unsteady thrust and torque acting on the propeller Sample calculations as well as wind tunnel and flight test results are presented which illustrates the sensitivity of a propeller to flow field in which it is operating

/pdf/the-analysis-of-propellers-including-interaction-effects-1q2bwmis5c.pdf

Z. N. Martinovic

Papers

The Analysis of Propellers Including Interaction Effects