Skype Skype Me™!, tel. (044) 228-18-35, e-mail: kimo.biz at gmail.com
English  Русский 

CHOOSE YOUR LANGUAGE

Catalog

Blog / News

22.10.2012 20:43:55
23.08.2011
03.11.2009
Subscribe for email newsletter (blog):
or RSS 2.0

Survey

Printer friendly version Printer friendly version

6.2. Interaction of single module device with a flow of fluid. Theoretical assumptions.

Rate it

Crank mechanism with a work item is a module that is placed on a fixed base. The scheme of interaction with the device single module flow of the fluid at which the conversion of kinetic energy of the fluid flow into useful work, is shown in FIG. 3.

Designation:
1 - a work item;
2 - the flow of air;
L - the phase angle between displacement and force;
P - force exerted by the flow on the lateral surface of the working element, perpendicular to the reciprocating movement of the working element;
Pn - normal component of the force exerted by the flow of P on the lateral surface of the work item, which coincides with the direction of the reciprocating movement of the working element;
Pc - the resulting component of force P, perpendicular to the lateral surface of the working element;
PUAI - total UAI of unsteady aerodynamic forces and moments;
A - initial time;
B - phase shift of 90 degrees relative to the initial moment of time;
C - 180 degrees phase shift relative to the initial moment of time;
D - 270-degree phase shift relative to the start time.

The arrows indicate the direction of reciprocating movement of a work item, occurring due to the impact of stream 2 and the total impact of UAI to work items 1.

In [18], the formula 42 shows that, if the force acts in the direction of movement, the greatest work per cycle of oscillation will occur when the phase shifts between displacement and force of 90 degrees.

                                                                                                                     (1)

where W - work done by the disturbing force of a cycle in
steady-state forced vibrations
п- dimensionless mathematical constant, which expresses
ratio of the circumference to its diameter and length equal to 3.14;
A - amplitude;
P - the disturbing force;
L - the phase angle between displacement and force.

Therefore, the proposed device, the reciprocating movement of the work item should be arranged perpendicular to the direction of motion of the fluid flow. In this case, the normal component of the power flux Pn impact on the lateral surface of the working element coincides with the movement of a work item, and the resulting component perpendicular to the side surface Pc of the working element.
At the same time a work item will perform harmonic rotational movement about the axis of its fastening. Angle of attack of L (the angle between the lateral surface of the working element and the direction of flow) will be changed at any time, reaching a peak around the middle of the reciprocating movement and taking the value zero when changing the direction of the reciprocating movement of the work item.

According to the theoretical basis [17], the interaction of a work item, committing flexural-torsion vibrations of the air flow occurs flexural-torsion flutter. Consequently, there are transient aerodynamic forces and moments, the total UAI of which (Puai) can be the same (in the creation of certain conditions) to the direction of movement of the work item.
A condition in which the total UAI coincides with the direction of motion of the working element, is proposed device is designed in which the work item has the ability to perform rotational and reciprocating movements of constant amplitude and phase shift between the power to influence the flow and reciprocating movement of the working element is equal to of 90 degrees.

In implementing the proposed scheme of reciprocating and rotational motion of the working element in the flow of fluid in interaction with the flow of a fluid work the normal component of power Pn impact on the lateral surface of the work item and the total UAI of unsteady aerodynamic forces and moments (Puai) will always be the maximum at a given moment of time (except when changing the direction of reciprocating movement to the opposite, in this case, the normal component of the job Pn impact of power P on the lateral surface of the work item in accordance with the formula 42 [18] will be equal to zero, the total UAI of unsteady aerodynamic forces and moments (Puai) also takes the value zero, since the value of UAI directly depends on the flow rate [ 17] and the intensity of the interaction of a work item with the flow, zero angle of attack is the work item is due to the forces of inertia).

The device according to the scheme of its interaction with the flow of fluid, shown in Fig. 3, as follows.
A work item is placed in a flow of fluid 2 at an angle L with respect to the flow 2 with reciprocating movement in a direction perpendicular to the flow 2, and rotational movement about the axis 6, relative to which the working element 1 is mounted on a rod 3, and geometrical axis of shaft 6 is in the front of the element 1 (Figs. 1, 2). Flow of fluid 2 (Fig. 3) affects the operating element 1 in position "A" and creates a force that moves the work item in a direction perpendicular to the flow 2 (direction indicated by arrow), and rotating around a work item to axis 6 (Figs. 1, 2). At the same time there are unsteady aerodynamic forces and moments, the total UAI of which (Puai) is the force of the stream and also move the work item in a direction perpendicular to the flow 2 (direction indicated by arrow), and rotating the operating element 1 around the axis 6 (Fig. 1, 2).
The vector normal component of "Pn" the driving force of the flow of "P" and the vector of total UAI "Puai" (Fig. 3) coincides with the direction of movement of a work item, and the resulting "Pc" the driving force of the flow of "P" is perpendicular to the lateral surface of a work item . Angle «L» between the working element 1 and the direction of flow is reduced, thus reducing the magnitude and impact of flow 2 in the work item 1. In position "B" work item 1 changes the direction of movement is reversed, the angle of «L» = 0, the impact of flow 2 in a work item is not, nor is the total Puai, and the position of "B" work item is out of inertia due to the energy rotation of the crank 8 (Figs. 1, 2). After passage of the "B" (Fig. 3), the angle «L» is different from zero, respectively, there are efforts Pn and Puai, coinciding with the inertial force of the impact of the crank 8 (Figs. 1, 2) and moving a work item to the " C "(Fig. 3), the angle «L»is increasing, while the normal component of vector "Pn" the driving force of the flow of "P" and the vector of total UAI coincide with the direction of movement of a work item, and the resulting "Pc" the driving force of the flow of "P" perpendicular to the lateral surface of the working element 1. The maximum impact flow 2 and Puai at the operating element 1 in position "A" and "C", and the angle «L» a maximum and becomes equal to 45 degrees (in this case). After passage of the "C" angle «L» is reduced, respectively, decreases the value of the impact of stream 2 and the total UAI on a work item 1. In the situation of «D» work Item 1 changes the direction of movement is reversed, the angle of «L» = 0, 2, and the impact of the flow of the total UAI on a work item is missing, and the position of «D» a work item is out of inertia due to rotational energy crank 8 (Figs. 1, 2). After passage of «D» (Fig. 3), the angle «L» is different from zero, respectively, there is an effort that coincides with the inertial force of the impact of the crank 8 (Figs. 1, 2) and moving the operating element 1 in position "A" ( Fig. 3), the angle «L» is increasing, while the normal component of vector "Pn" driving force flow "P" and the vector of total UAI "Puai" coincides with the direction of movement of a work item, and the resulting "Pc" the driving force of the flow of "P" perpendicular to the lateral surface of the working element 1. Then the process repeats.

Any questions?

Please use the following form to request information.

Your name:

Email

Please specify your question about 6.2. Interaction of single module device with a flow of fluid. Theoretical assumptions.:


Type the numbers you see in the picture below
code

© .