Helicopter Vibration Reduction throughout the Entire Flight Envelope Using Surrogate-Based Optimization

Abstract

The effectiveness of surrogate-based optimization of helicopter rotor blades for vibration reduction at both low-and highspeed forward flight is studied. The efficient global optimization (EGO) algorithm is used to conduct a global search of the design space. Vibration levels in the low-speed regime are caused primarily by blade-vortex interaction (BVI), and vibrations at high advance ratios are caused by dynamic stall. Although the source of high vibrations is different for both flight conditions, the results show that the EGO algorithm is effective in finding reduced vibration designs at both flightconditions. Furthermore, the results indicate that it is possible to design a blade with reduced vibration levels at both flight conditions. However, a single design that is best for both flight conditions does not exist. Therefore, multiobjective function optimization techniques were employed to identify Pareto optimal designs.

Optimisation of aspects of rotor blades in forward flight

“…This was not the case on the aerodynamics front due to the lack of efficient and accurate modelling techniques (Celi, 1999;Ganguli, 2004) although some progress was also made (Ganguli, 2004). Nevertheless, several authors (Celi, 1999;Walsh, 1991;Le Pape and Beaumier, 2005;Imiela, 2009;Glaz et al, 2008Glaz et al, , 2009Tatossian et al, 2008;Allen et al, 2010) have attempted to devise a variety of optimisation techniques. However, these methods were limited either by their efficiency or the accuracy of the results; reason being that high-fidelity computational fluid dynamics (CFD) simulations are necessary to accurately capture the effects of design changes, especially for rotor aerodynamics and a number of CFD solutions are required for the process with each calculation taking substantial computational time.…”

“…The high cost of CFD computations is an issue mentioned by several authors; one of the ways of overcoming this difficulty is to use a model of the CFD solution, a meta-model or surrogate model, as also used by Ganguli (2004). Glaz et al (2008Glaz et al ( , 2009) used non-gradient surrogatebased optimisation for vibration reduction of a BO-105 rotor. Tatossian et al (2008) took a different approach to shape optimisation of hovering rotors, improving the adverse transonic flow effects at tip Mach numbers of 0.85 and above.…”

Optimization of the Kinematics of a Flapping Wing MAV in Hover for Enhanced Performance

“…The surrogate modeling approach followed here is similar to that described in Ref. 20, and is illustrated in Fig. 4.…”

“…20,24,25 An expected improvement function (EIF) 24,25 , defined based on the local error in prediction, is used to identify regions of the parameter space where there is a high probability of producing a superior design over the current best design, and/or where the predictions of the surrogate are unreliable due to a high amount of uncertainty. Subsequently, additional sample points are identified by maximizing the EIF.…”

Multidisciplinary Design Optimization: A Survey of Architectures

“…One of the first applications of MDO was aircraft wing design, where aerodynamics, structures, and controls are three strongly coupled disciplines [9,10,11,12,13,14,15,16]. Since then, the application of MDO has been extended to complete aircraft [17,18,19,20,21] and a wide range of other engineering systems, such as bridges [22], buildings [23,24], railway cars [25,26], microscopes [27], automobiles [28,29], ships [30,31], propellers [32,33], rotorcraft [34,35], wind turbines [36,37,38], and spacecraft [39,40].…”