A method for flight-test determination of propulsive efficiency and drag

Bull, Gifford; Bridges, Philip D.

doi:10.2514/3.45108

Cited by 10 publications

(2 citation statements)

References 3 publications

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“…For many biological cases, however, the act of propulsion involves significant flexure of the animal body and/or fluid-dynamic interaction of the propulsors with the body, making it unlikely that the drag for the propelled and unpropelled animals are the same (Barrett et al 1999, Blake 2004). Even for propellerdriven aircraft, the flow induced by the propeller can significantly affect the flow over the fuselage and hence, aircraft drag coefficients determined in power-off glide tend to give artificially low values for η P (Bull and Bridges 1985). A similar interaction between the vehicle body and propulsor occurs in ships, known as the propellerhull interaction (Bertram 2000, Newman 1977.…”

Section: Evaluating Propulsive Performance Using P Mechmentioning

confidence: 99%

“…In this case, it is not necessary to assume equality of aircraft drag in powered and unpowered flight. A third technique extracts η P from the transient response of the aircraft to an abrupt increase in power (Bull and Bridges 1985). As is apparent from these approaches, indirect methods typically require accurate knowledge of or models for aircraft drag.…”

Section: Introductionmentioning

confidence: 99%

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Measurement of propulsive power and evaluation of propulsive performance from the wake of a self-propelled vehicle

Krueger¹

2006

Bioinspir. Biomim.

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Propulsive efficiency is a key indicator of propulsive performance, but it can be difficult to measure when the propulsion system is integrated into the vehicle body because the average rate of useful work done propelling the vehicle (Wu) and/or the average mechanical power expended propelling the vehicle (Pmech) is not known directly. A general approach would be to determine either or both of (Wu) and (Pmech) from the vehicle wake. The present discussion demonstrates that only (Pmech) can be determined from the flow crossing a plane a fixed (average) distance downstream of the vehicle. A method for measuring (Pmech) is presented using the observation that the power required to tow a permeable obstruction behind the vehicle depends on (Pmech). Several methods for evaluating propulsive performance using [Formula: see text] are proposed, including the definition of an equivalent jet velocity and corresponding Froude efficiency if the time-averaged mass flow rate through the propulsion system is known. If only (Pmech) is known, the recommended measure of propulsive performance is a power coefficient defined analogous to a drag coefficient.

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Section: Evaluating Propulsive Performance Using P Mechmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Measurement of propulsive power and evaluation of propulsive performance from the wake of a self-propelled vehicle

Krueger¹

2006

Bioinspir. Biomim.

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Deriving the Generalized Total Kinetic Power Equation for Jet Engine

Lee¹,

Lee²

1998

J. mech.

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In light of incessant quest of better propulsion performance, it would be opportune to probe some propulsion insights for jet engine (JE) from a power point of view. In this study, we endeavor to prescribe logic reasoning process for obtaining the JE total kinetic power and prove its degenerated counterpart. With the Lagrangian Reynolds transport approach, we also rigorously derive the highly generalized equation for this power. Moreover, the validity, significance, and importance of this novel generalized power equation are delicately demonstrated by an interesting spring/mass model with known total kinetic power. Notably, the JE total kinetic power equations are quite reasonable physically speaking, since all the velocity quantities involved are of relative nature; otherwise, the JE total kinetic power may violate the energy conservation law under certain conditions. This total kinetic power produced by jet engine involves a few more physical effects including vehicle acceleration, relative flow velocity/steadiness, inlet/exit pressures, and gravity, thus open an original route for more efficient propulsion design.

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Deriving the Generalized Rocket Kinetic Power Equations and Associated Propulsion Indexes.

Lee¹,

Lee²

1999

JSME international journal. Ser. B, Fluids and thermal engineer

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A method for flight-test determination of propulsive efficiency and drag

Cited by 10 publications

References 3 publications

Measurement of propulsive power and evaluation of propulsive performance from the wake of a self-propelled vehicle

Measurement of propulsive power and evaluation of propulsive performance from the wake of a self-propelled vehicle

Deriving the Generalized Total Kinetic Power Equation for Jet Engine

Deriving the Generalized Rocket Kinetic Power Equations and Associated Propulsion Indexes.

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