Design of distributed propulsion system for general aviation airplane
01 Jan 2019-Vol. 304, pp 03009
TL;DR: In this paper, a small airplane is redesigned by using a distributed electrical propulsion (DEP) system and the design procedure is focused on the reduction of fuel consumption in cruise regime with constrained parameters of take-off/landing.
Abstract: In this paper, a small airplane is redesigned by using a distributed electrical propulsion (DEP) system. The design procedure is focused on the reduction of fuel consumption in cruise regime with constrained parameters of take-off/landing. In this case, a one half wing area compared to an original airplane is used. Take-off distance and minimum airspeed for landing is achieved by distributed propellers mounted on the leading edge of the wing. These propellers induce velocity on the wing and thereby increase local dynamic pressure, thus the required lift force can be reached with smaller wing area. Moreover, the distributed propellers are assumed as folded in cruise regime to minimize drag when the main combustion engine provides sufficient power.
01 Jan 2021
TL;DR: In this paper, the authors focused on the usage of distributed electric propulsion (DEP) in order to increase the aerodynamic efficiency of a ten-seater aircraft by using lifting line theory with blade element momentum theory.
Abstract: This paper is focused on the usage of distributed electric propulsion (DEP) in order to increase aerodynamic efficiency. A ten seats aircraft is used as a case study. New design uses the existing fuselage, tail and turboprop engine, only wing is completely redesigned. The cost function for the design procedure consists of two parts. The first one is aerodynamic efficiency, which has a primary impact on fuel consumption, and the second one is weight of the wing. Lifting line theory with blade element momentum theory is used to design a wing geometry with DEP. Optimal geometry is also verified by CFD simulation. The estimation of the wing weight is needed for the second part of the cost function. This was done by the design of elementary wing parts under CS-23 regulation. The wing is assumed as full-aluminium with two spars. The main goal of this optimization is to redesign the wing for a given range and save as much fuel as possible.
TL;DR: In this article, an approximate solution for the irrotational motion of a screw surface in an inviscid fluid was given by Prandtl, which is the main object of this work to find the exact solution.
Abstract: The vortex-theory of screw propellers develops along similar lines to aerofoil theory. There is circulation of flow round each blade; this circulation vanishes at the tip and the root. The blade may be replaced by a bound vortex system, which, for the sake of simplicity, may be taken, as a first approximation, to be a bound vortex line. The strength of the vortex at any point is equal to Γ, the circulation round the corresponding blade section. From every point of this bound vortex spring free, trailing vortices, whose strength per unit length is —∂Γ/∂ r , where r is distance from the axis of the screw. When the interference flow of this vortex system is small compared with the velocity of the blades, the trailing vortices are approximately helices, and together build a helical or screw surface. Part of the work supplied by the motor is lost in producing the trailing vortex system. When the distribution of Γ along the blade is such that, for a given thrust, the energy so lost per unit time is a minimum, then the flow far behind the screw is the same as if the screw surface formed by the trailing vortices was rigid, and moved backwards in the direction of its axis with a constant velocity, the flow being that of classical hydro dynamics in an inviscid fluid, continuous, irrotational, and without circulation. The circulation round any blade section is then equal to the discontinuity in the velocity potential at the corresponding point of the screw surface. Further, for symmetrical screws, the interference flow at the blade is half that at the corresponding point of the screw surface far behind the propeller. An approximate solution for the irrotational motion of a screw surface in an inviscid fluid was given by Prandtl. The accuracy of the approximation increases with the number of blades and with the ratio of the tip speed to the velocity of advance, but for given values of these numbers we have no means of estimating the error, since the exact solution of the problem has not yet been found. It is the main object of this work to find the exact solution.
"Design of distributed propulsion sy..." refers methods in this paper
...It represents simplified version of the Goldstein's method ....
••12 Jul 2018
TL;DR: The emergence of distributed electric propulsion (DEP) concepts for aircraft systems has enabled new capabilities in the overall efficiency, capabilities, and robustness of future air vehicles and provides flexible operational capabilities far beyond those of current systems.
Abstract: The emergence of distributed electric propulsion (DEP) concepts for aircraft systems has enabled new capabilities in the overall efficiency, capabilities, and robustness of future air vehicles Distributed electric propulsion systems feature the novel approach of utilizing electrically-driven propulsors which are only connected electrically to energy sources or power-generating devices As a result, propulsors can be placed, sized, and operated with greater flexibility to leverage the synergistic benefits of aero-propulsive coupling and provide improved performance over more traditional designs A number of conventional aircraft concepts that utilize distributed electric propulsion have been developed, along with various short and vertical takeoff and landing platforms Careful integration of electrically-driven propulsors for boundary-layer ingestion can allow for improved propulsive efficiency and wake-filling benefits The placement and configuration of propulsors can also be used to mitigate the trailing vortex system of a lifting surface or leverage increases in dynamic pressure across blown surfaces for increased lift performance Additionally, the thrust stream of distributed electric propulsors can be utilized to enable new capabilities in vehicle control, including reducing requirements for traditional control surfaces and increasing tolerance of the vehicle control system to engine-out or propulsor-out scenarios If one or more turboelectric generators and multiple electric fans are used, the increased effective bypass ratio of the whole propulsion system can also enable lower community noise during takeoff and landing segments of flight and higher propulsive efficiency at all conditions Furthermore, the small propulsors of a DEP system can be installed to leverage an acoustic shielding effect by the airframe, which can further reduce noise signatures The rapid growth in flight-weight electrical systems and power architectures has provided new enabling technologies for future DEP concepts, which provide flexible operational capabilities far beyond those of current systems While a number of integration challenges exist, DEP is a disruptive concept that can lead to unprecedented improvements in future aircraft designs
01 Jan 1919
01 Feb 1979
05 Jun 2017
TL;DR: In this article, an airfoil and high-lift flap for the X-57 Maxwell Distributed Electric Propulsion (DEP) testbed aircraft was designed and evaluated with USM3D.
Abstract: A computational and design study on an airfoil and high-lift flap for the X-57 Maxwell Distributed Electric Propulsion (DEP) testbed aircraft was conducted. The aircraft wing sizing study resulted in a wing area of 66.67 sq ft and aspect ratio of 15 with a design requirement of V(stall) = 58 KEAS, at a gross weight of 3,000 lb. To meet this goal an aircraft C(L,max) of 4.0 was required. The design cruise condition is 150 KTAS at 8,000 ft. This resulted in airfoil requirements of c(l) is approximately 0.90 for the cruise condition at Re = 2.35 x 10 (exp 6). A flapped airfoil with a c(l,max) of approximately 2.5 or greater, at Re = 1.0 x 10 (exp 6), was needed to have enough lift to meet the stall requirement with the DEP system. MSES computational analyses were conducted on the GAW-1, GAW-2, and the NACA 5415 airfoil sections, however they had limitations in either high drag or low c(l,max) on the cruise airfoil, which was the impetus for a new design. A design was conducted to develop a low drag airfoil for the X-57 cruise conditions with high c(l,max). The final design was the GNEW5BP93B airfoil with a minimum drag coefficient of c(d) = 0.0053 at c(l) = 0.90 and achieved laminar flow back to 69% chord on the upper surface and 62% chord on the lower surface. With fully turbulent flow, the drag increases to c(d) = 0.0120. The predicted maximum lift with turbulent flow is a c(l,max) of 1.95 at alpha = 19 deg. The airfoil is characterized by relatively flat pressure gradient regions on both surfaces at alpha = 0 deg, and aft camber to get extra lift out of the lower surface concave region. A 25% chord slotted flap was designed and analyzed with MSES for a 30 deg flap deflection. Additional 30 deg and 40 deg flap deflection analyses for two flap positions were conducted with USM3D using several turbulence models, for two angles of attack, to assess near c(l,max) with varied flap position. The maximum c(l) varied between 2.41 and 3.35. An infinite-span powered high-lift study was conducted on a GAW-1 constant chord 40 deg flapped airfoil section with FUN3D to quantify the airfoil lift increment that can be expected from a DEP system. The 16.7 hp/propeller blown wing increases the maximum C(L) from 3.45 to C(L) = 6.43, which is an effective q ratio of 1.86. This indicates that if the unblown high-lift flapped airfoil of the X-57 airplane achieves a c(l,max) of 2.78, then the high-lift augmentation blowing could yield a sectional lift coefficient of approximately 4.95 at c(l,max). Finally, a computational study was conducted with FUN3D on an infinite-span constant chord GAW-1 cruise airfoil to determine the impact of high-lift propeller diameter to wing chord ratio on the lift increment of the DEP system. A constant diameter propeller and nacelle size were used in the study. Three computational grids were made with airfoil chords of 0.5*chord, 1.0*chord, and 2.0*chord. Results of the propeller diameter to wing chord ratio study indicated that the blown to unblown C(L) ratio increased as the chord was decreased. However, because of the increase in relative size of the high-lift nacelle to the wing, which impacted wing lift performance, the study indicated that a propeller diameter to wing chord ratio of 1.0 gives the overall best maximum lift on the wing with the DEP system.
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