VIII. The order of laboratory work performance

The measurements of pressure of an air flow in different cross - sections of wind tunnel carry out at the fixed modes of operations of the fan, that is at constant values of tension and current in an electrical circle feed of the fan (rated power of the fan will be const).

1. The pitot – static tube should be established in a working section of the wind tunnel in parallel with direction of air flow. The pitot – static tube should be connected to the inclined tube manometer with the help of flexible tubing.

2. Measure the areas of cross section of the wind tunnel in places, where the receivers of static pressure established. Expediently measurements carry out on entrance and exit of contraction, diffuser, settling chamber and corners.

3. The established receivers of static pressure in different sections of the wind tunnel connect in pairs with help of flexible tubing to another inclined tube manometer.

4. An air flow speed in a working section of the wind tunnel should be defined according to pressure difference measured with the help of the inclined tube manometer, using the formula (7). Necessary for calculations value of air density define from the equation of state for a gas, previously measuring temperature and pressure of air in laboratory with the help of the thermometer and barometer accordingly.

5. Repeat measurements of air speed flow in a working section of the wind tunnel disconnecting tubing of static pressure from the inclined tube manometer. Compare results of measurement to results of item 4 for a substantiation of a conclusion about equality between static pressure in a working section of the wind tunnel and pressure in a laboratory room.

6. The distinctions of static pressure of an air flow in different sections the wind tunnel measure with the help of the inclined tube manometer.

7. Using results of accounts from item 2, 5 and the equation of continuity define speed of an air flow in different sections of the wind tunnel.

As a result of laboratory work performance and analysis of the received results the student should know:

1. Using the Bernoulli’s equation and the equation of continuity explain a principle of action and design of wind tunnels. Explain purpose of their separate parts.

2. Sketch an open jet and a closed type of wind tunnel, suitable for subsonic speeds.

3. Describe the methods by which air speed may be measured.

4. Explain an action principle of air speed indicator.

5. Explain an action principle of an inclined tube manometre.

The list of literature

1. Мхитарян а.М. Аэродинамика: Учебник для авиационных специальностей вузов. - г.: Машиностроение, 1976. - 446 с.

2. АЭРОГИДРОМЕХАНИКА: Учебник для авиационных специальностей вузов /А.М. Мхитарян, В.В. Ушаков, А.Г. Баскакова, В.Д. Трубенок. Под общ. ред. А.М. Мхитаряна. - Г.: Машиностроение, 1984. - 352 с.

3. БЕЛОВА Ю.П.,БУРАВЦЕВ А.И., КОВАЛЕВ М.А., МАТВЕЕВ С.К. Лабораторный практикум по аэрогазодинамике: Учебное пособие для вузов. Изд-во Ленинградского ун-та. 1980. - 288 с.

4. ГОСТ 29281-78. Аэродинамика летательных аппаратов. Термины, определения и буквенные обозначения. - Введ. 01.07.1979.

5. ГОСТ 4401-81. Атмосфера стандартная. Параметры. - Введ. 10.07.1982.

6. Аэродинамические измерения, методы и приборы. Лабораторная работа №1, учебно – методическое издание, Киев, КИИГА, 1990, Составитель Петренко В.Л.