The Jet Airplane Utilizing Boundary Layer Air for Propulsion

Smith, A. M. O.; Roberts, Howard E.

doi:10.2514/8.1273

Cited by 69 publications

(45 citation statements)

References 2 publications

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“…Their collective work established wake-ingesting propulsors as an efficient propulsion system design for torpedo and other marine applications. In 1993, interest in BLI applications to aircraft design was renewed when Smith (5) introduced the concept of the power saving coefficient (PSC) to measure the improvement relative to a non-BLI baseline, which he defined as PSC = Pwr 0 shaft ÀPwr shaft Pwr 0 shaft : … (1) This metric compared the power required by the BLI configuration (Pwr shaft ) with the power of a reference podded configuration (Pwr 0 shaft ). Comparing performance based on the power is useful because, as Betz (3) showed, the more traditional metric of propulsive efficiency is illdefined for BLI applications, since it can have values greater than 1.…”

Section: Introductionmentioning

confidence: 99%

Coupled aeropropulsive design optimisation of a boundary-layer ingestion propulsor

Gray

Martins

2018

Aeronaut. j.

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Airframe–propulsion integration concepts that use boundary-layer ingestion (BLI) have the potential to reduce aircraft fuel burn. One concept that has been recently explored is NASA’s STARC-ABL aircraft configuration, which offers the potential for fuel burn reduction by using a turboelectric propulsion system with an aft-mounted electrically driven BLI propulsor. So far, attempts to quantify this potential fuel burn reduction have not considered the full coupling between the aerodynamic and propulsive performance. To address the need for a more careful quantification of the aeropropulsive benefit of the STARC-ABL concept, we run a series of design optimisations based on a fully coupled aeropropulsive model. A 1D thermodynamic cycle analysis is coupled to a Reynolds-averaged Navier–Stokes simulation to model the aft propulsor at a cruise condition and the effects variation in propulsor design on overall performance. A series of design optimisation studies are performed to minimise the required cruise power, assuming different relative sizes of the BLI propulsor. The design variables consist of the fan pressure ratio, static pressure at the fan face, and 311 variables that control the shape of both the nacelle and the fuselage. The power required by the BLI propulsor is compared with a podded configuration. The results show that the BLI configuration offers 6–9% reduction in required power at cruise, depending on assumptions made about the efficiency of power transmission system between the under-wing engines and the aft propulsor. Additionally, the results indicate that the power transmission efficiency directly affects the relative size of the under-wing engines and the aft propulsor. This design optimisation, based on computational fluid dynamics, is shown to be essential to evaluate current BLI concepts and provides a powerful tool for the design of future concepts.

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Section: Introductionmentioning

confidence: 99%

Coupled aeropropulsive design optimisation of a boundary-layer ingestion propulsor

Gray

Martins

2018

Aeronaut. j.

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“…BLI systems invalidate this assumption by design. In 1947, the first theoretical study of BLI noted that it would introduce a significant dependence between aircraft drag and engine airflow [7]. Decades later Smith and Robers [8] quantified this interaction from the propulsion system perspective, by relating the propulsive efficiency to a set of nondimensional viscous wake parameters.…”

Section: Introductionmentioning

confidence: 99%

Approach to Modeling Boundary Layer Ingestion using a Fully Coupled Propulsion-RANS Model

Gray

Mader

Kenway

et al. 2017

58th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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Airframe-propulsion integration concepts that use boundary layer ingestion have the potential to reduce aircraft fuel burn. One concept that has been recently explored is NASA's Starc-ABL aircraft configuration, which offers the potential for 12% mission fuel burn reduction by using a turbo-electric propulsion system with an aft-mounted electrically driven boundary layer ingestion propulsor. This large potential for improved performance motivates a more detailed study of the boundary layer ingestion propulsor design, but to date, analyses of boundary layer ingestion have used uncoupled methods. These methods account for only aerodynamic effects on the propulsion system or propulsion system effects on the aerodynamics, but not both simultaneously. This work presents a new approach for building fully coupled propulsive-aerodynamic models of boundary layer ingestion propulsion systems. A 1D thermodynamic cycle analysis is coupled to a RANS simulation to model the Starc-ABL aft propulsor at a cruise condition and the effects variation in propulsor design on performance are examined. The results indicates that both propulsion and aerodynamic effects contribute equally toward the overall performance and that the fully coupled model yields substantially different results compared to uncoupled. The most significant finding is that boundary layer ingestion, while offering substantial fuel burn savings, introduces throttle dependent aerodynamics effects that need to be accounted for. This work represents a first step toward the multidisciplinary design optimization of boundary layer ingestion propulsion systems.

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“…The concept of boundary layer control is not a new one. Early research suggested that the application of constant suction on the aircraft surface could reduce the drag of the aircraft through removal of the boundary layer [3]. The boundary layer also has the potential to be of benefit to the propulsion system through the application of boundary layer ingestion (BLI).…”

Section: Introductionmentioning

confidence: 99%

Installed Performance Assessment of a Boundary Layer Ingesting Distributed Propulsion System at Design Point

Goldberg¹,

Nalianda²,

MacManus³

et al. 2016

52nd AIAA/SAE/ASEE Joint Propulsion Conference

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Boundary layer ingesting systems have been proposed as a concept with great potential for reducing the fuel consumption of conventional propulsion systems and the overall drag of an aircraft. These studies have indicated that if the aerodynamic and efficiency losses were minimised, the propulsion system demonstrated substantial power consumption benefits in comparison to equivalent propulsion systems operating in freestream flow. Previously assessed analytical methods for BLI simulation have been from an uninstalled perspective. This research will present the formulation of an rapid analytical method for preliminary design studies which evaluates the installed performance of a boundary layer ingesting system. The method uses boundary layer theory and one dimensional gas dynamics to assess the performance of an integrated system.The method was applied to a case study of the distributed propulsor array of a blended wing body aircraft. There was particular focus on assessment how local flow characteristics influence the performance of individual propulsors and the propulsion system as a whole. The application of the model show that the spanwise flow variation has a significant impact on the performance of the array as a whole. A clear optimum design point is identified which minimises the power consumption for an array with a fixed configuration and net propulsive force requirement. In addition, the sensitivity of the system to distortion related losses is determined and a point is identified where a conventional free-stream propulsor is the lower power option. Power saving coefficient for the configurations considered is estimated to lie in the region of 15%. NomenclatureAcronyms AR = Aspect ratio BL = Boundary layer BLC = Boundary layer control BLI = Boundary layer ingestion BWB = Blended wing Body FPR = Fan pressure ratio FS = Free-stream KE = Kinetic energy KEG = Kinetic energy non-dimensional group * PhD Researcher, Propulsion Engineering Centre, Cranfield University, Student Member. † Lecturer, Propulsion Engineering Centre, Cranfield University.

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The Jet Airplane Utilizing Boundary Layer Air for Propulsion

Cited by 69 publications

References 2 publications

Coupled aeropropulsive design optimisation of a boundary-layer ingestion propulsor

Coupled aeropropulsive design optimisation of a boundary-layer ingestion propulsor

Approach to Modeling Boundary Layer Ingestion using a Fully Coupled Propulsion-RANS Model

Installed Performance Assessment of a Boundary Layer Ingesting Distributed Propulsion System at Design Point

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