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Ducted propeller equivalent advance ratio working condition calculation method

A technology of propeller and forward ratio, applied in the field of effective forward ratio working condition estimation, can solve the problems of initial condition error, inability to take into account the effect of duct-induced equivalent inflow, and increasing the number of iterative revisions.

Active Publication Date: 2015-09-16
COOL HIGH TECH BEIJING CO LTD
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  • Summary
  • Abstract
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  • Application Information

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Problems solved by technology

However, there is currently no estimation method for this equivalent forward ratio, and the equivalent incoming flow induced by the duct cannot be included in the preliminary design, so there is a large error in the initial conditions of the propeller in the design duct, which increases the Iterative Revisions

Method used

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  • Ducted propeller equivalent advance ratio working condition calculation method
  • Ducted propeller equivalent advance ratio working condition calculation method
  • Ducted propeller equivalent advance ratio working condition calculation method

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Embodiment Construction

[0048] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0049] The present invention is a method for calculating the equivalent advance ratio working condition of the propeller in the duct, which is carried out according to the following steps:

[0050] The advance ratio is also called the advance distance ratio, which is defined as where V 0 is the incoming flow velocity, in m / s. For the propeller in hovering condition, V 0 =0m / s, n is the rotation speed of the propeller, unit r / s, D propeller diameter.

[0051] The equivalent advance ratio proposed by the present invention is to assume that the propeller under the action of the ducted propeller under the hovering condition is assumed to be under the equivalent working condition that the open propeller works at V with the same rotating speed. 0 Equivalent front flow conditions. where V 0 The induced velocity part is considered to be caused...

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Abstract

The invention discloses a ducted propeller equivalent advance ratio working condition calculation method. According to the method, fitting is conducted on the relation of the tension coefficient under a certain angle of attack of an open propeller and the advance ratio through an equation; the ducted tension factor q and the outlet area ratio sigma are determined; a thin cylindrical ducted propeller calculation formula is adopted for the ducted tension factor q; the open propeller tension T1 is obtained by inputting the rotating speed and the current advance ratio, the initial V1 is worked out through the formula (please see the formula in specification), and the equivalent incoming flow speed V0 is calculated through the formula (please see the formula in specification); the equivalent advance ratio lambada n is obtained through the equivalent incoming flow V0 and the current rotating speed; judgment and convergence are conducted. The method is simple, easy to implement and free of tests or massive fluid mechanics calculation and has larger operation efficiency and convenience.

Description

technical field [0001] The invention belongs to the technical field of aviation propellers, and relates to a calculation method for the working condition of the equivalent advance ratio of propellers in a duct. Background technique [0002] A ducted propeller is a propeller surrounded by a duct. Since the ducted propeller involved in the present invention is mainly used for hovering and low-speed vertical take-off and landing of aircraft, that is, there is only a small incoming flow velocity in the axial direction, the design of this type of ducted propeller does not consider the working condition of large forward ratio. Considering the most commonly used working conditions and facilitating theoretical analysis and research, the equivalent advance ratios of the present invention are all based on the hovering working conditions of the ducted propeller. [0003] The lift generated by the ducted propeller in the hovering condition comes from two parts: the duct and the propell...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F17/50
Inventor 樊伟徐彬项昌乐
Owner COOL HIGH TECH BEIJING CO LTD
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