Abstract:PurposeAerodynamic characteristics of engine side air intakes for a lightweight helicopter are investigated aiming to achieve an efficient engine airframe integration.
Design/methodology/approachOn a novel full-scale model of a helicopter fuselage section, a comprehensive experimental data set is obtained by wind tunnel testing. Different plenum chamber types along with static side intake and semi-dynamic side intake configurations are considered. Engine mass flow rates corresponding to the power requirements… Show more
“…Static air inlets can be located at the side of the aerial vehicle. However, their poor total pressure ratio at higher speeds limits their use to helicopters only [11]. For supersonic aircraft, inlets with variable geometries are mostly utilised to attain optimal shock configurations [12].…”
Section: Figure 3 Air Inlet Types By Typical Aircraft Cruise Velocitymentioning
Hydrogen fuel cell-powered electrified propulsion systems hold great promise for the development of sustainable aircraft. However, the integration of fuel cells into aircraft presents unique challenges, particularly in the context of air inlet systems. Key development priorities are to ensure a constant supply of air to the fuel cells and to efficiently manage the transfer of waste heat from the fuel cells. This paper investigates different air inlet systems using analytical methods. Firstly, concepts are identified by analysing the state of the art in air inlet design. Secondly, promising concepts are selected through a qualitative evaluation. Finally, the most promising concept is sized for the given topology. The results of this research highlight the importance of careful air inlet design in order to achieve operability and acceptable performance with fuel cell powered aero engines. The performance and sizing data obtained from the performed analytical calculations can serve as a general basis for the preliminary design of scoop inlets and annular inlets for fuel cell-powered aircraft.
“…Static air inlets can be located at the side of the aerial vehicle. However, their poor total pressure ratio at higher speeds limits their use to helicopters only [11]. For supersonic aircraft, inlets with variable geometries are mostly utilised to attain optimal shock configurations [12].…”
Section: Figure 3 Air Inlet Types By Typical Aircraft Cruise Velocitymentioning
Hydrogen fuel cell-powered electrified propulsion systems hold great promise for the development of sustainable aircraft. However, the integration of fuel cells into aircraft presents unique challenges, particularly in the context of air inlet systems. Key development priorities are to ensure a constant supply of air to the fuel cells and to efficiently manage the transfer of waste heat from the fuel cells. This paper investigates different air inlet systems using analytical methods. Firstly, concepts are identified by analysing the state of the art in air inlet design. Secondly, promising concepts are selected through a qualitative evaluation. Finally, the most promising concept is sized for the given topology. The results of this research highlight the importance of careful air inlet design in order to achieve operability and acceptable performance with fuel cell powered aero engines. The performance and sizing data obtained from the performed analytical calculations can serve as a general basis for the preliminary design of scoop inlets and annular inlets for fuel cell-powered aircraft.
“…The 35° bend was necessary to accommodate the pipe in a space-constrained area, a feature also seen in the wind tunnel testing of a helicopter fuselage section of Knoth and Breitsamter. 22 As a result, secondary flows emanate from the centrifugal force acting on the primary flow at the pipe bend, and appear in the form of counter-rotating vortices, otherwise known as Dean vortices. 23 This regime of the flow is highly complex and hence, the pipe inlet boundary conditions for CFD was placed a certain distance away from the bend as opposed to the start of the blower.Figure 1.Cross-sectional view of the engine cowling.…”
The ability to predict the characteristics of engine exhaust is important to determining heat signatures on various components of the aircraft body. This is often obtained through numerical means such as RANS, which however relies closely on the choice of the turbulence model for accurate predictions. In this study, predictions of exhaust plumes from four turbulence models are compared against results from particle image velocimetry of a scaled helicopter engine exhaust. These models include the standard k − ϵ, realizable k − ϵ, shear-stress transport (SST) k − ω, and Durbin’s turbulence models. All four turbulence models managed to capture the general shape of the exhaust when analyzed through the velocity contours at two measurement windows. However, the comparisons of velocity contours fail to describe the shift of the predicted plume from the experiments, which is important for fuselage/tail impingement. To obtain further insights to the shifts, a visual correlation in the form of a confidence ellipse through principal component analysis (PCA) is introduced and plotted for the predicted plumes. All the models’ plume predictions showed quantifiable shifts in their mean-centers when compared to the measurements. In terms of matching the measurements’ statistical maximum variance of the plume distribution at the furthermost plane, it was found that the realizable k − ϵ performed the best among the models. On the other hand, the SST k − ω and Durbin’s model performed the best in predicting bivariate ( x and y coordinates) distribution of the plume at the furthermost plane.
Aerodynamic characteristics of helicopter engine side air intakes are investigated. The experimental data set is obtained by wind tunnel testing of a full-scale helicopter fuselage section model. For the simulation of realistic engine operation, engine mass flow rates are reproduced. Five-hole pressure probe data of the aerodynamic interface plane as well as local surface pressure distributions are compared for different geometries and operation conditions. Previous investigations indicate that unshielded, sideways-facing air intakes yield lowest distortion and highest total pressure levels in low speed conditions. In fast forward flight condition, however, forward-facing intake shapes are more beneficial. On this basis, the current research assesses the optimization potential of retrofit modifications such as a rear spoiler (small scoop) and an intake guide vane. Two optimal configurations of retrofit modifications are identified, combining benefits of the various basic intake and plenum chamber shapes.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
