Propulsive Efficiency of Wake Ingestion

Recent Advances in Boundary Layer Ingestion Technology of Evolving Powertrain Systems

“…However, Bevilaqua and Yam [31] presented a different approach based on a physicsbased analysis to investigate the BLI effect on the propulsive power and propulsive efficiency. They investigated a concept in which a propeller accelerated the wake of a blunt body back to the freestream velocity and derived that the useful thrust power by the propeller (P out ) is the thrust (T) times the inflow velocity of the slipstream (V w ) as shown in Equation (6).…”

“…For the interested reader, a discussion on the origin of the equation was presented by Cavcar [34]. For the BLI technology, it was used by Bevilaqua and Yam [31] as well as Seitz et al [35]. An adapted definition of the Brèguet-Coffin equation was presented for the cruise portion since this mission phase is dominant in the majority of long haul aircraft families.…”

“…Bevilaqua and Yam [31] performed a control volume analysis for the cruise operating condition with a 1D flow employing an actuator disk to simulate a propeller that accelerates the wake of a body until the jet velocity reaches the freestream velocity. The authors used the propulsive efficiency derivations shown in Section 2 and found a reduction in propulsive efficiency when employing wake ingestion.…”

“…The research efforts focusing on the propulsive fuselage concept are summarized in Tables 3 and 4 Other studies [31] propeller in body's wake uniform flow propeller propulsive efficiency analysis; Brèguet-Coffin equation higher potential range; lower available kinetic energy [146] full-electric turboprop aircraft analytical calculations 25% benefit in energy efficiency [147] aft-mounted BLI propulsor Boeing 737-800 2D axisymmetric CFD studies power savings of 81-85% can be achieved [149] propulsor in the body's wake no experimental and 3D CFD studies reduced required power for same net axial force [150] thin haul PFC aircraft no mathematical analysis using an actuator model importance of velocity deficit parameter and overall energy efficiency [151] propeller in body's wake twin-turbo propeller aircraft (EIS 2035) BL profile from 1/7th power law; investigated thrust split and BLI propeller loading BLI presented negligible benefits [152] hybrid-electric aircraft; aft-BLI propeller ATR 42-500 aircraft FLOPS-based method; different tools integrated importance of synergistic benefits [153] aft-mounted BLI fan baseline BLI geometry optimization to minimize the distortion on the fan vertical tail-plane increases distortion levels [154,155] all-electric podded configuration RANS CFD studies power savings ranged between 3.4 to 4.9%; 20 dB noise reduction [156] partial turbo-electric conventional aircraft with two engines three levels of BLI thrust; CFD simulations; main engine redesign 2.8% fuel burn increase; 1.7% fuel burn increase after optimization [164] aft-mounted BLI fan no power balance method; 2D CFD models low FPR favorable; importance of thrust split [36] partial turbo-electric clean inflow propeller blade element theory; potential and 1/7 power law BL use of system level PSC; 1.5 to 5% power saving A chronological order illustration showing the start and finish publication dates of the most intensively boundary layer ingestion concepts studied in the open literature is presented in Figure 11. An interesting aspect emerging from this timeline illustration is that initial research efforts focused on radically changed aircraft concepts, moving away from the traditional tube-and-wing aircraft geometry.…”

Innovative Energy-Saving Propulsion System for Low-Speed Biomimetic Underwater Vehicles

“…The energy efficiency of the propulsion system [22,32] is defined as the ratio of useful power output to the rate of power input measured over a specific time interval [33,34].…”