CN110207934B - Method for effectively prolonging flow time of large-size free piston high-enthalpy pulse wind tunnel - Google Patents
Method for effectively prolonging flow time of large-size free piston high-enthalpy pulse wind tunnel Download PDFInfo
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Abstract
A method for effectively prolonging the flow time of a large-size free piston high-enthalpy pulse wind tunnel relates to the technical field of wind tunnel tests; the method comprises the following steps: step one, dividing a spray pipe configuration into a contraction section AT and an expansion section TF along the axial direction; the contraction section AT and the expansion section TF are axially connected; the intersection point T is the position of the throat; determining the position of the throat T; taking the throat T as a reference, dividing the expansion section TF into a first section TC, a second section CE and a third section EF; respectively designing the pipeline configurations of a first section TC, a second section CE and a third section EF; dividing a contraction section AT into a contraction front section AB and a contraction rear section BT by taking the throat T as a reference; respectively designing the pipeline configurations of the shrinkage front section AB and the shrinkage rear section BT; the invention effectively prolongs the running time of the wind tunnel flow field; meanwhile, the operation state of the wind tunnel can be adjusted by replacing the inner diameter of the throat, and parts which cause local ablation of the throat due to high temperature can be conveniently replaced.
Description
Technical Field
The invention relates to the technical field of wind tunnel tests, in particular to a method for effectively prolonging the flow time of a large-size free piston high-enthalpy pulse wind tunnel.
Background
The large-size free piston high enthalpy pulse wind tunnel is one of the main ground simulation devices for researching high temperature real gas effect, and has the capability of simulating ultrahigh speed flow. Under ultra-high speed flow conditions, the free incoming flow at the nozzle outlet has a dimensional effect. In order to reduce the influence of the absolute size of the nozzle on the free incoming flow, the size of the nozzle needs to be large enough, and the size of the corresponding shock tube and the size of the compression tube are also large. For a large-size free piston high-enthalpy pulse wind tunnel, due to the fact that the inner diameter of a shock tube is large, after a diaphragm of a main film clamping mechanism breaks, the acceleration of a free piston in the running process of the tail end of a compression tube is too high, potential safety hazards are caused to a piston and the wind tunnel, and meanwhile, the constant pressure driving time of the compression tube is reduced, so that the test time of the wind tunnel is too short, and the test capability of the wind tunnel is influenced. At present, no related technology for effectively solving the wind tunnel test capability exists.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a method for effectively prolonging the flow time of a large-size free piston high-enthalpy pulse wind tunnel, so that the running time of a wind tunnel flow field is effectively prolonged; meanwhile, the operation state of the wind tunnel can be adjusted by replacing the inner diameter of the throat, and parts which cause local ablation of the throat due to high temperature can be conveniently replaced.
The above purpose of the invention is realized by the following technical scheme:
the method for effectively prolonging the flow time of the large-size free piston high-enthalpy pulse wind tunnel comprises the steps that a wind tunnel test spray pipe comprises a compression pipe, a main film clamping section, a spray pipe configuration and a shock tube; the compression pipe, the main film clamping section, the spray pipe configuration and the shock tube are sequentially communicated along the axial direction; the compression tube has an inner diameter D1; the inner diameter of the main laminating section is D2; the inner diameter of the shock tube is D3; the method for prolonging the flow time of the large-size free piston high enthalpy pulse wind tunnel comprises the following steps:
step one, dividing a spray pipe configuration into a contraction section AT and an expansion section TF along the axial direction; the contraction section AT and the expansion section TF are axially connected; the intersection point T is the position of the throat; determining the position of the throat T;
taking the throat T as a reference, dividing the expansion section TF into a first section TC, a second section CE and a third section EF; respectively designing the pipeline configurations of a first section TC, a second section CE and a third section EF;
dividing a contraction section AT into a contraction front section AB and a contraction rear section BT by taking the throat T as a reference; respectively designing the pipeline configurations of the shrinkage front section AB and the shrinkage rear section BT;
and step four, finishing the design of the spray pipe configuration.
In the method for effectively prolonging the flow time of the large-size free piston high-enthalpy pulse wind tunnel, in the first step, the axial A end of the contraction section AT is communicated with the main film clamping section; the inner diameter of the axial end A of the contraction section AT is D2; the axial F end of the expansion section TF is communicated with the shock tube; the expansion section TF has an inner diameter D3 at the axial F-end.
In the above method for effectively prolonging the flow time of the large-size free piston high enthalpy pulse wind tunnel, in the first step, the inner diameter Dt at the throat T is
In the above method for effectively prolonging the flow time of the large-size free piston high enthalpy pulse wind tunnel, in the second step, the method for designing the pipeline configurations of the first section TC, the second section CE, and the third section EF is as follows:
s1, establishing an expansion section TF coordinate system OXY;
s2, establishing a characteristic line equation of the first section TC;
s3, establishing a characteristic line equation of a third section EF;
s4, the second section CE is a conical section; the axial C end of the second section CE is connected with the first section TC, and the smooth transition joint is the C end; the axial E end of the second section CE is connected with the third section EF; the smooth transition junction is at the E-terminus.
In the above method for effectively prolonging the flow time of the large-size free piston high enthalpy pulse wind tunnel, in S1, the method for establishing the expansion section TF coordinate system OXY is as follows: taking the position of the spray pipe configuration axis corresponding to the throat T as a coordinate origin O; the X direction horizontally points to the F end of the expansion section TF; the Y direction is vertically upward.
In the above method for effectively prolonging the flow time of the large-size free piston high enthalpy pulse wind tunnel, in S2, the characteristic line equation of the first section TC is:
wherein M is Mach number;
x is an x-axis variable in an expansion section TF coordinate system OXY;
y is a y-axis variable in an expansion section TF coordinate system OXY;
theta is the maximum expansion angle, and the angle is 6-15 degrees;
gamma is the driving gas coefficient in the compression pipe, and gamma is 1.667.
In the above method for effectively prolonging the flow time of the large-size free piston high enthalpy pulse wind tunnel, in S3, the characteristic line equation of the third segment EF is:
wherein M is Mach number;
x is an x-axis variable in an expansion section TF coordinate system OXY;
y is a y-axis variable in an expansion section TF coordinate system OXY;
theta is the maximum expansion angle, and the angle is 6-15 degrees;
gamma is the driving gas coefficient in the compression pipe, and gamma is 1.667.
In the third step, the method for designing the configurations of the pipelines of the contraction front section AB and the contraction rear section BT is as follows:
s1, the contracted section BT is an arc section; the radius of the contracted section BT is the same as that of the first section TC at the point T of the throat;
s2, the contraction front section AB is a conical section, and the contraction front section AB is designed.
In the above method for effectively prolonging the flow time of the large-size free piston high enthalpy pulse wind tunnel, in S2, the axial B end of the contraction front section AB is connected to the contraction rear section BT, and the smooth transition connection is the B end.
In the method for effectively prolonging the flow time of the large-size free piston high enthalpy pulse wind tunnel, only the MN section of the spray pipe configuration needs to be replaced when the spray pipe configuration is replaced; wherein the M end is positioned between the cone contraction front section AB; the N-terminal is located between the conical second sections CE.
Compared with the prior art, the invention has the following advantages:
(1) the invention solves the problem that the piston stop is difficult due to the large inner diameters of the compression pipe and the shock tube of the large-size free piston high enthalpy pulse wind tunnel. The flow of gas at the tail end of the compression pipe entering the shock tube after the main laminated film is broken can be reduced, the deceleration time of the heavy piston running in the compression pipe is prolonged, the constant pressure driving time of the wind tunnel is prolonged, and the safety allowance of the piston running is increased;
(2) the invention can slow down the interference of an expansion wave system generated after the main diaphragm is broken on the contact discontinuous surface, thereby effectively prolonging the operation time of the wind tunnel flow field;
(3) the invention adopts a characteristic line method to design an expansion section and adopts a cone and circular arc designed contraction section, thereby effectively reducing the incident shock wave loss;
(4) the invention can adjust the running state of the wind tunnel by changing the inner diameter of the throat, and can also conveniently replace parts which cause partial ablation of the throat due to high temperature. M and N points of the MTN of the throat changing area are respectively arranged on the CE conical section of the expansion section and the AB conical section of the contraction section, and the throat changing area cannot affect the wave absorbing area of the original expansion section and the entrance of the contraction section.
Drawings
FIG. 1 is a schematic flow diagram illustrating the extension of wind tunnel flow time according to the present invention;
FIG. 2 is a schematic view of a wind tunnel test nozzle structure according to the present invention.
Detailed Description
The invention is described in further detail below with reference to the following figures and specific examples:
the invention provides a method for effectively prolonging the flow time of a large-size free piston high-enthalpy pulse wind tunnel, which improves the test capability of the wind tunnel by adding a spray pipe configuration 3 to a main film clamping section 2 and a shock tube 4. The flow of gas at the tail end of the compression pipe entering the shock tube 4 after the main laminated section 2 is broken is reduced, the deceleration time of the heavy piston in the compression pipe 1 is prolonged, the constant pressure driving time of the wind tunnel is prolonged, the safety allowance of the piston in operation is increased, the interference of an expansion wave system generated after the main laminated section 2 is broken on the contact discontinuous surface is relieved, and the operation time of a wind tunnel flow field is further effectively prolonged; meanwhile, the operation state of the wind tunnel can be adjusted by replacing the inner diameter of the throat, and parts which cause local ablation of the throat due to high temperature can be conveniently replaced.
As shown in fig. 1, which is a schematic flow diagram for prolonging the flow time of a wind tunnel, it can be known that a wind tunnel test nozzle includes a compression pipe 1, a main sandwich section 2, a nozzle configuration 3 and a shock tube 4; the compression pipe 1, the main laminated section 2, the spray pipe configuration 3 and the shock tube 4 are sequentially communicated along the axial direction; the inner diameter of the compression tube 1 is D1; the inner diameter of the main laminating section 2 is D2; the inner diameter of the shock tube 4 is D3; the method for prolonging the flow time of the large-size free piston high enthalpy pulse wind tunnel comprises the following steps:
step one, as shown in fig. 2, a schematic structural diagram of a wind tunnel test nozzle is shown, and as can be seen from the diagram, a nozzle configuration 3 is divided into a contraction section AT and an expansion section TF along the axial direction; the contraction section AT and the expansion section TF are axially connected; the intersection point T is the position of the throat; determining the position of the throat T; the axial A end of the contraction section AT is communicated with the main laminating section 2; the inner diameter of the axial end A of the contraction section AT is D2; the axial F end of the expansion section TF is communicated with the shock tube 4; the expansion section TF has an inner diameter D3 at the axial F-end. The internal diameter Dt of the throat T is
Taking the throat T as a reference, dividing the expansion section TF into a first section TC, a second section CE and a third section EF; respectively designing the pipeline configurations of a first section TC, a second section CE and a third section EF;
the method for designing the pipeline configuration of the first section TC, the second section CE and the third section EF comprises the following steps:
s1, establishing an expansion section TF coordinate system OXY; the method for establishing the expansion section TF coordinate system OXY comprises the following steps: taking the axis position of the nozzle configuration 3 corresponding to the throat T as a coordinate origin O; the X direction horizontally points to the F end of the expansion section TF; the Y direction is vertically upward.
S2, establishing a characteristic line equation of the first section TC;
the characteristic line equation of the first section TC is:
wherein M is Mach number;
x is an x-axis variable in an expansion section TF coordinate system OXY;
y is a y-axis variable in an expansion section TF coordinate system OXY;
theta is the maximum expansion angle, and the angle is 6-15 degrees; this angle range can be expanded appropriately according to the actual situation.
γ is a driving gas coefficient in the compression pipe 1, and γ is 1.667.
S3, establishing a characteristic line equation of a third section EF;
the characteristic line equation of the third section EF is:
wherein M is Mach number;
x is an x-axis variable in an expansion section TF coordinate system OXY;
y is a y-axis variable in an expansion section TF coordinate system OXY;
theta is the maximum expansion angle, and the angle is 6-15 degrees; this angle range can be expanded appropriately according to the actual situation.
γ is a driving gas coefficient in the compression pipe 1, and γ is 1.667.
S4, the second section CE is a conical section; the axial C end of the second section CE is connected with the first section TC, and the smooth transition joint is the C end; the axial E end of the second section CE is connected with the third section EF; the smooth transition junction is at the E-terminus.
Dividing a contraction section AT into a contraction front section AB and a contraction rear section BT by taking the throat T as a reference; respectively designing the pipeline configurations of the shrinkage front section AB and the shrinkage rear section BT;
the method for designing the configurations of the pipeline of the contraction front section AB and the contraction rear section BT comprises the following steps:
s1, the contracted section BT is an arc section; the radius of the contracted section BT is the same as that of the first section TC at the point T of the throat;
s2, the contraction front section AB is a conical section, and the contraction front section AB is designed. The axial B end of the contraction front section AB is connected with the contraction rear section BT, and the smooth transition connection position is the B end.
And step four, finishing the design of the spray pipe configuration 3.
When the spray pipe configuration 3 is replaced, only the MN section of the spray pipe configuration 3 needs to be replaced; wherein the M end is positioned between the cone contraction front section AB; the N-terminal is located between the conical second sections CE. The contraction front section AB and the second section CE both adopt contraction sections designed by cones and circular arcs, and the incident shock wave loss can be effectively reduced.
The invention adopts a characteristic line method to design an expansion section and adopts a cone and circular arc designed contraction section, thereby effectively reducing the incident shock wave loss; the operation state of the wind tunnel can be adjusted by replacing the inner diameter of the throat, and parts which cause partial ablation of the throat due to high temperature can be replaced conveniently. M and N points of the MTN of the throat changing area are respectively arranged on the CE conical section of the expansion section and the AB conical section of the contraction section, and the throat changing area cannot affect the wave absorbing area of the original expansion section and the entrance of the contraction section.
Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known in the art.
Claims (7)
1. The method for effectively prolonging the flow time of the large-size free piston high-enthalpy pulse wind tunnel is characterized by comprising the following steps of: the wind tunnel test spray pipe comprises a compression pipe (1), a main laminated film section (2), a spray pipe configuration (3) and a shock tube (4); the compression pipe (1), the main laminated section (2), the spray pipe configuration (3) and the shock tube (4) are sequentially communicated along the axial direction; the inner diameter of the compression tube (1) is D1; the inner diameter of the main laminating section (2) is D2; the inner diameter of the shock tube (4) is D3; the method for prolonging the flow time of the large-size free piston high enthalpy pulse wind tunnel comprises the following steps:
step one, dividing a spray pipe configuration (3) into a contraction section AT and an expansion section TF along the axial direction; the contraction section AT and the expansion section TF are axially connected; the intersection point T is the position of the throat; determining the position of the throat T;
taking the throat T as a reference, dividing the expansion section TF into a first section TC, a second section CE and a third section EF; respectively designing the pipeline configurations of a first section TC, a second section CE and a third section EF;
dividing a contraction section AT into a contraction front section AB and a contraction rear section BT by taking the throat T as a reference; respectively designing the pipeline configurations of the shrinkage front section AB and the shrinkage rear section BT;
step four, completing the design of the spray pipe configuration (3);
in the first step, the axial A end of the contraction section AT is communicated with the main laminating section (2); the inner diameter of the axial end A of the contraction section AT is D2; the axial F end of the expansion section TF is communicated with the shock tube (4); the inner diameter of the axial F end of the expansion section TF is D3;
in the first step, the inner diameter Dt of the throat T is
In the second step, the method for designing the pipeline configurations of the first section TC, the second section CE and the third section EF is as follows:
s1, establishing an expansion section TF coordinate system OXY;
s2, establishing a characteristic line equation of the first section TC;
s3, establishing a characteristic line equation of a third section EF;
s4, the second section CE is a conical section; the axial C end of the second section CE is connected with the first section TC, and the smooth transition joint is the C end; the axial E end of the second section CE is connected with the third section EF; the smooth transition junction is at the E-terminus.
2. The method for effectively prolonging the flow time of a large-size free piston high enthalpy pulse wind tunnel according to claim 1, characterized in that: in the step S1, the method for establishing the expansion section TF coordinate system OXY comprises: taking the axial line position of the nozzle configuration (3) corresponding to the throat T as a coordinate origin O; the X direction horizontally points to the F end of the expansion section TF; the Y direction is vertically upward.
3. The method for effectively prolonging the flow time of the large-size free piston high enthalpy pulse wind tunnel according to claim 2, wherein: in S2, the characteristic line equation of the first segment TC is:
wherein M is Mach number;
x is an x-axis variable in an expansion section TF coordinate system OXY;
y is a y-axis variable in an expansion section TF coordinate system OXY;
theta is the maximum expansion angle, and the angle is 6-15 degrees;
gamma is the driving gas coefficient in the compression pipe (1), and gamma is 1.667.
4. The method for effectively prolonging the flow time of the large-size free piston high enthalpy pulse wind tunnel according to claim 3, wherein: in S3, the characteristic line equation of the third segment EF is:
wherein M is Mach number;
x is an x-axis variable in an expansion section TF coordinate system OXY;
y is a y-axis variable in an expansion section TF coordinate system OXY;
theta is the maximum expansion angle, and the angle is 6-15 degrees;
gamma is the driving gas coefficient in the compression pipe (1), and gamma is 1.667.
5. The method for effectively prolonging the flow time of the large-size free piston high enthalpy pulse wind tunnel according to claim 4, wherein: in the third step, the method for designing the configurations of the pipelines of the contraction front section AB and the contraction rear section BT comprises the following steps:
s1, the contracted section BT is an arc section; the radius of the contracted section BT is the same as that of the first section TC at the point T of the throat;
s2, the contraction front section AB is a conical section, and the contraction front section AB is designed.
6. The method for effectively prolonging the flow time of the large-size free piston high enthalpy pulse wind tunnel according to claim 5, wherein: in the step S2, the axial B end of the contraction front section AB is connected to the contraction rear section BT, and the smooth transition connection is the B end.
7. The method for effectively prolonging the flow time of the large-size free piston high enthalpy pulse wind tunnel according to claim 6, wherein: when the spray pipe configuration (3) is replaced, only the MN section of the spray pipe configuration (3) needs to be replaced; wherein the M end is positioned between the cone contraction front section AB; the N-terminal is located between the conical second sections CE.
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