A Correction Method for Aircraft Bottom Drag Coefficient

Abstract

The invention provides a method for correcting the drag coefficient at the bottom of an aircraft to solve the problems existing in the current method for correcting the drag coefficient at the bottom of the aircraft. Including: 1. Design test device: including a wind tunnel test model, a force-measuring balance, a balance pole and four pressure-measuring tubes. Protrude from the bottom of the wind tunnel test model, and four pressure measuring tubes are evenly fixed on the upper, lower, left, and right sides of the balance pole; 2. Calculate the drag coefficient correction at the bottom of the aircraft, including: 2.1 Model when setting the first attack angle The attitude stabilization time is t, and the pressure data of four piezometric tubes are collected every Δt time within t1 after the stabilization is over, t>t1; 2.2 Set the data collection method under the remaining angles of attack: the model under each angle of attack The attitude stabilization time is t1. During the t1 time, the pressure data of four piezometric tubes are collected every Δt time; 2.3 Based on the pressure data obtained in 2.1 and 2.2, calculate the correction amount of the bottom drag coefficient of the aircraft.

Description

technical field [0001] The invention belongs to the technical field of aircraft aerodynamic performance prediction, and in particular relates to a method for correcting the drag coefficient at the bottom of an aircraft. Background technique [0002] The drag coefficient is a very important parameter for aircraft performance analysis. It has an important impact on the control accuracy, maneuverability, range, etc. during flight. Therefore, it is very important to obtain an accurate aircraft drag coefficient. At present, the wind tunnel test is still the main means to obtain the drag coefficient of the aircraft. Generally, the drag coefficient measured by the balance in the wind tunnel test includes two parts: the front body drag coefficient of the test model and the drag coefficient on the entire bottom section. No resistance is generated, so the drag coefficient corresponding to the nozzle outlet section needs to be deducted from the full elastic drag coefficient obtained f...

AI Technical Summary

Problems solved by technology

However, in this method, there are the following problems when dealing with the drag coefficient at the bottom of the aircraft: on the one hand, when deducting the drag coefficient corresponding to the entire bottom surface, the bottom pressure data used is the bottom pressure value measured during the conventional dynamometric test. , due to the complexity of the flow field, the bottom pressure at each angle of attack is usually not stabilized during the conventional dynamometric test, resulting in a large error in the converted bottom resistance, which in turn affects the aircraft front drag obtained in the test.

On the other hand, the real aircraft bottom drag coefficient obtained by CFD calculation is affected by complex flow phenomena such as calculation grid, calculation format and flow separation, and the calculation error is also large

Therefore, there are certain defects in this method of processing the drag coefficient at the bottom of the aircraft.

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