CN114148508A - Control device for inhibiting boundary layer interference flow separation - Google Patents
Control device for inhibiting boundary layer interference flow separation Download PDFInfo
- Publication number
- CN114148508A CN114148508A CN202111628528.XA CN202111628528A CN114148508A CN 114148508 A CN114148508 A CN 114148508A CN 202111628528 A CN202111628528 A CN 202111628528A CN 114148508 A CN114148508 A CN 114148508A
- Authority
- CN
- China
- Prior art keywords
- flow
- boundary layer
- spanwise
- flow control
- separation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C23/00—Influencing air flow over aircraft surfaces, not otherwise provided for
- B64C23/06—Influencing air flow over aircraft surfaces, not otherwise provided for by generating vortices
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T50/00—Aeronautics or air transport
- Y02T50/10—Drag reduction
Landscapes
- Engineering & Computer Science (AREA)
- Aviation & Aerospace Engineering (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
Abstract
The invention discloses a control device for inhibiting boundary layer interference flow separation, which comprises: an array of a plurality of flow control units for generating streamwise vortices to inhibit boundary layer interfering flow separation, the array being disposed in front of an aircraft surface shock turbulent boundary layer interfering flow separation zone. The invention can inhibit the boundary layer from interfering the flow separation.
Description
Technical Field
The invention relates to the field of control devices, in particular to a control device for inhibiting boundary layer interference flow separation.
Background
The shock wave/turbulent flow boundary layer interference is widely existed in the internal and external flow fields of various supersonic and hypersonic aircrafts. The induced flow separation phenomenon can bring large energy loss, high-frequency pulsation of aerodynamic resistance, surface heat flow and pressure load is caused, and unpredictable aerodynamic force and aerodynamic moment are generated, so that the control of the aircraft is difficult to effectively implement, and the fatigue of the body structure can be caused. Therefore, the method effectively controls the interference flow separation of the shock wave/turbulent flow boundary layer in the complex flight environment in the flight of various supersonic and hypersonic aircrafts, and is of great importance for improving the performance index of the aircrafts.
The generation mechanism of the interference induced flow separation of the shock wave/turbulent flow boundary layer is that the pressure difference before and after the strong shock wave leads to the generation of strong adverse pressure gradient in the boundary layer and further leads to flow separation. Therefore, the energy distribution in the boundary layer is improved, the capability of the turbulent boundary layer for resisting the adverse pressure gradient is enhanced, and the key technology for controlling the interference flow separation of the shock wave/turbulent boundary layer is provided. At present, various active and passive control technologies such as boundary layer blowing and sucking, micro-jet vortex generators, magnetohydrodynamic force, plasma control and the like are used under the condition of low speed, the purpose of flow separation control is achieved by adjusting energy distribution in the boundary layer, injecting extra energy and the like, and the method has certain application. However, the research and application in high-speed flow fields of shock wave/turbulent boundary layer interference are less. Because the high-speed flow field is extremely sensitive to the appearance of the aircraft, the control technology which is directly applied at the conventional low speed is often ineffective, and even the control device can induce new adverse interference.
Disclosure of Invention
The invention aims to provide a control device for inhibiting boundary layer interference flow separation, and aims to solve the problem of inhibiting boundary layer interference flow separation.
A control apparatus for suppressing boundary layer interference flow separation, comprising:
an array of a plurality of flow control units for generating streamwise vortices to inhibit boundary layer interfering flow separation, the array being disposed in front of an aircraft surface shock turbulent boundary layer interfering flow separation zone.
Preferably, the distance between the rear edge of the device and the boundary line of the separation area is less than or equal to 15 delta, wherein delta is the thickness of the local boundary layer.
Preferably, the array comprises at least 2 rows of flow control units, and the array is distributed at equal intervals in the spanwise direction.
Preferably, the at least 2 rows of flow control units are arranged uniformly over the surface of the aircraft in the flow direction.
Preferably, the spanwise distribution pitch of the flow control units is less than or equal to 4 δ.
Preferably, the number of the spanwise flow control units is rounded up in the ratio of the spanwise length of the separation zone to the spanwise span of a single flow control unit.
Preferably, the sum of one half of the span-wise distribution spacing and the span-wise width of the leading edge of the control element is the span-wise span of the single flow control element.
Preferably, the arrays are staggered along the flow direction between two adjacent rows of flow control units.
Preferably, the flow control unit is of a miniature passive type and is in the shape of a triangular wedge.
Preferably, the maximum height h of the flow control unit is less than or equal to 0.5 delta, the flow direction length L is less than or equal to 4 delta, and the half vertex angle alpha of the triangle is 14 degrees.
By adopting the embodiment of the invention, the flow direction vortex with stable performance is generated by arranging the micro passive flow control unit at the upstream of the separation area. The flow direction vortexes interact in the spanwise direction, so that the energy and the flow structure in the boundary layer are adjusted, and the control of flow separation is realized.
The height of the micro flow control unit does not exceed the height of a local boundary layer, the structure additional resistance is small, and new interference and other adverse effects cannot be induced in supersonic and hypersonic flow fields.
The invention strengthens the flow direction vortex generated by the device by arranging a plurality of rows of flow control units, strengthens the adjustment capability of the flow direction vortex on the internal energy and the flow structure of the turbulent flow boundary layer, and realizes the effective control of the interference flow separation of the high-speed flow field shock wave/turbulent flow boundary layer.
According to the invention, through the staggered distribution of the control units, the distribution density of the flow direction vortexes generated by the device along the spanwise direction (namely perpendicular to the flow direction) is effectively improved, and the spanwise distance of the miniature passive flow control units can be further increased.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a schematic view of an installation position of a control device for suppressing boundary layer disturbance flow separation according to an embodiment of the present invention.
Fig. 2 is a schematic perspective view of a single flow control unit of the control device for suppressing boundary layer interference flow separation according to the embodiment of the present invention.
FIG. 3 is a schematic diagram of the individual flow control unit size parameters of a control apparatus for suppressing boundary layer interfering flow separation according to an embodiment of the present invention.
Fig. 4 is a schematic diagram of an array of control units of a control apparatus for suppressing boundary layer disturbance flow separation according to an embodiment of the present invention.
Fig. 5 is a diagram showing a result of numerical simulation of suppressing separation of boundary layer disturbance flow by the control apparatus for suppressing separation of boundary layer disturbance flow according to the embodiment of the present invention.
Fig. 6 is a diagram showing the results of numerical simulation of suppressing turbulent boundary layer interfering flow separation by the control apparatus for suppressing boundary layer interfering flow separation according to the embodiment of the present invention.
Fig. 7 is a schematic diagram of three control effects of the control device, a single control unit and a single row of control units according to the embodiment of the present invention.
FIG. 8 is a schematic diagram illustrating the control effect of the control device and the in-line control unit array according to the embodiment of the present invention.
Description of reference numerals:
101: a control device; 102: a separation line; 103: a separation zone.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise. Furthermore, the terms "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Device embodiment
According to an embodiment of the present invention, there is provided a control device for suppressing boundary layer interference flow separation, and fig. 1 is a schematic installation position diagram of the control device for suppressing boundary layer interference flow separation according to an embodiment of the present invention, as shown in fig. 1, specifically including:
an array of a plurality of flow control units for generating streamwise vortices, the array being disposed in front of an aircraft surface shock turbulent boundary layer disturbance flow separation zone. The distance between the rear edge of the device and the boundary line of the separation area is less than or equal to 15 delta, wherein delta is the thickness of the local boundary layer. The array comprises at least 2 rows of flow control units, and the array is distributed at equal intervals in the spanwise direction.
At least 2 rows of flow control units are arranged uniformly over the aircraft surface in the flow direction. The spanwise distribution pitch of the flow control units is less than or equal to 4 delta. The number of the spanwise flow control units is the ratio of the spanwise length of the separation area to the spanwise span of a single flow control unit which is rounded up. The sum of one half of the span-wise distribution spacing and the span-wise width of the leading edge of the control element is the span-wise span of the single flow control element. The arrays are distributed in a staggered manner along two rows of flow control units adjacent to each other in the flow direction. The flow control unit is of a micro passive type and is in a triangular wedge shape. The maximum height h of the flow control unit is less than or equal to 0.5 delta, the flow direction length L is less than or equal to 4 delta, and the half vertex angle alpha of the triangle is 14 degrees.
As shown in fig. 1, the control device of the present invention is installed upstream of the shock/turbulent boundary layer disturbance separation point with the device trailing edge not more than 15 δ from the separation line 102, δ being the local turbulent boundary layer thickness. By arranging the control device 101 at the upstream of the separation region 103, the airflow forms a stable flow vortex at the downstream of the control device, and the stable flow vortex is mutually influenced with a turbulent boundary layer in the downstream flow process to adjust the energy distribution and the flow field structure in the boundary layer, so that the flow separation is inhibited.
Fig. 2 is a schematic perspective view of a single flow control unit of a control device for suppressing boundary layer interference flow separation according to an embodiment of the present invention, and as shown in fig. 2, the single flow control unit constituting the control device array of the present invention has a micro-triangular wedge structure. The forward flow direction is low in the front and high in the back, and wide in the front and narrow in the back.
Fig. 3 is a schematic diagram of the size parameters of a single flow control unit of the control device for suppressing boundary layer interference flow separation according to the embodiment of the present invention, and as shown in fig. 3, three views and an isometric view of the single flow control unit are respectively given. The critical dimension parameters of a single flow control unit include the maximum height h, the flow direction length L and the triangle half apex angle α. Wherein the maximum height h is not more than 0.5 δ; the length L of the flow direction does not exceed 4 delta, and the half vertex angle alpha of the triangle is 14 degrees.
Fig. 4 is a schematic diagram of an array manner of control units of a control device for suppressing boundary layer interference flow separation according to an embodiment of the present invention, as shown in fig. 4: the key parameters comprise the span-wise distance delta Z and the flow-direction distance delta X of the control unit and the flow-direction arrangement row number N. Wherein the spanwise spacing Delta Z is less than or equal to 4 delta. The number of the single-row spanwise arrangement is determined by a spanwise interval delta Z and a separation region spanwise coverage to be controlled together, specifically, the number M of the spanwise units is an upward integer of a ratio of the spanwise length of the separation region to the spanwise span of each unit, the spanwise span of each unit is a sum of one half of the spanwise distribution interval and the spanwise width of the front edge of the control unit, and the spanwise width of the front edge of each control unit is uniquely determined by a half angle of the control unit and the flow direction length through a simple geometric relationship. The flow direction interval Delta X is less than or equal to 4 delta. The number of rows N of flow direction arrangement is determined by the simulation result according to the flow control index to be achieved.
The invention is applied to restrain the flow separation of the supersonic compression corner interference area, and the practical effect of the control device is verified in a CFD numerical simulation mode. Supersonic compression corner flow is a typical situation with shock/turbulent boundary layer interference flow characteristics, under the conditions of this example, flow separation caused by shock/turbulent boundary layer interference occurs in the corner interference zone.
Fig. 5 is a diagram showing a result of numerical simulation of suppressing separation of boundary layer disturbance flow by a shock wave of the control apparatus for suppressing separation of boundary layer disturbance flow according to the embodiment of the present invention, as shown in fig. 5:
fig. 6 is a diagram showing the results of numerical simulation of suppressing turbulent boundary layer interfering flow separation by the control apparatus for suppressing boundary layer interfering flow separation according to the embodiment of the present invention, as shown in fig. 6:
after the control device is installed, the separation point is delayed from the coordinate of-27.3 mm to-10.5 mm, and the attachment point is advanced from 21.2mm to 6.8 mm. The separation zone is reduced as a whole.
In this example, the numerical simulations performed by the device of the invention were compared with a single control unit and a single row of control units.
Fig. 7 is a schematic diagram of three control effects of the control device, a single control unit and a single row of control units according to the embodiment of the present invention, as shown in fig. 7:
wherein the separation point of a single control unit is-19.5 mm, and the reattachment point is 13.1 mm; the separation point under the action of the single-row control unit is-16.4 mm, and the attachment point is 10.2 mm. The control device of the present invention can further suppress the separation region.
Fig. 8 is a schematic diagram of the control effect of the control device and the in-line control unit array according to the embodiment of the invention, as shown in fig. 8: the control effect of the control device of the invention is compared with that of the in-line control unit array. In contrast, the staggered array along the flow direction of the present invention can effectively further suppress the separation region.
By adopting the embodiment of the invention, the flow direction vortex with stable performance is generated by arranging the micro passive flow control unit at the upstream of the separation area. The flow direction vortexes interact in the spanwise direction, so that the energy and the flow structure in the boundary layer are adjusted, and the control of flow separation is realized.
The height of the micro flow control unit does not exceed the height of a local boundary layer, the structure additional resistance is small, and new interference and other adverse effects cannot be induced in supersonic and hypersonic flow fields.
The invention strengthens the flow direction vortex generated by the device by arranging a plurality of rows of flow control units, strengthens the adjustment capability of the flow direction vortex on the internal energy and the flow structure of the turbulent flow boundary layer, and realizes the effective control of the interference flow separation of the high-speed flow field shock wave/turbulent flow boundary layer.
According to the invention, through the staggered distribution of the control units, the distribution density of the flow direction vortexes generated by the device along the spanwise direction (namely perpendicular to the flow direction) is effectively improved, and the spanwise distance of the miniature passive flow control units can be further increased.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; however, these modifications or alternative technical solutions of the embodiments of the present invention do not depart from the scope of the present invention.
Claims (10)
1. A control device for suppressing boundary layer interference flow separation, comprising:
an array of a plurality of flow control units for generating streamwise vortices to inhibit boundary layer interfering flow separation, the array being disposed forward of an aircraft surface shock turbulent boundary layer interfering flow separation zone.
2. The device of claim 1, wherein the device trailing edge is spaced from the edge of the separation zone by a distance of 15 δ or less, δ being the local boundary layer thickness.
3. The device of claim 2, wherein the array comprises at least 2 rows of flow control units, the array being equally spaced in a span-wise direction.
4. The apparatus of claim 3,
the at least 2 rows of flow control units are arranged uniformly over the aircraft surface in the flow direction.
5. The apparatus of claim 4,
the spanwise distribution pitch of the flow control units is less than or equal to 4 delta.
6. The apparatus of claim 5, wherein the number of spanwise flow control units is rounded up by the ratio of the spanwise length of the separation zone to the spanwise span of a single flow control unit.
7. The apparatus of claim 6, wherein the sum of one-half of the spanwise distribution spacing and the control element leading edge spanwise width is the single flow control element spanwise span.
8. The apparatus of claim 7, wherein the arrays are staggered in the flow direction between two adjacent rows of flow control units.
9. The device of claim 8, wherein the flow control unit is micro-passive and shaped as a triangular wedge.
10. The device according to claim 9, wherein the maximum height h of the flow control unit is less than or equal to 0.5 δ, the flow direction length L is less than or equal to 4 δ, and the half apex angle α of the triangle is 14 °.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111628528.XA CN114148508A (en) | 2021-12-28 | 2021-12-28 | Control device for inhibiting boundary layer interference flow separation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111628528.XA CN114148508A (en) | 2021-12-28 | 2021-12-28 | Control device for inhibiting boundary layer interference flow separation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114148508A true CN114148508A (en) | 2022-03-08 |
Family
ID=80449263
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111628528.XA Pending CN114148508A (en) | 2021-12-28 | 2021-12-28 | Control device for inhibiting boundary layer interference flow separation |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114148508A (en) |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6154882A (en) * | 1984-08-23 | 1986-03-19 | Nippon Kogaku Kk <Nikon> | Surface wave motor utilizing supersonic vibration |
| EP0850832A1 (en) * | 1996-12-09 | 1998-07-01 | Orlev Scientific Computing Limited | Method of and apparatus for controlling turbulance in boundary layer and other wall-bounded fluid flow fields |
| US20120018021A1 (en) * | 2009-09-30 | 2012-01-26 | The Board Of Trustees Of The University Of Illinois | Vortex generators to control boundary layer interactions |
| TW201225277A (en) * | 2010-02-24 | 2012-06-16 | Osram Opto Semiconductors Gmbh | Method for producing a plurality of optoelectronic semiconductor chips |
| CN103303469A (en) * | 2013-07-05 | 2013-09-18 | 上海交通大学 | Device for controlling flow separation caused by interference between high-Mach-number shock waves and boundary layers |
| JP2015068184A (en) * | 2013-09-27 | 2015-04-13 | 三菱日立パワーシステムズ株式会社 | Steam turbine rotor blade and steam turbine using steam turbine rotor blade |
| CN108303228A (en) * | 2017-08-08 | 2018-07-20 | 北京空天技术研究所 | A kind of boundary layer fluidised form control device and method of wind tunnel test |
| CN112395694A (en) * | 2020-12-03 | 2021-02-23 | 中国人民解放军国防科技大学 | Drag reduction control method for ultrahigh-speed turbulent boundary layer |
-
2021
- 2021-12-28 CN CN202111628528.XA patent/CN114148508A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6154882A (en) * | 1984-08-23 | 1986-03-19 | Nippon Kogaku Kk <Nikon> | Surface wave motor utilizing supersonic vibration |
| EP0850832A1 (en) * | 1996-12-09 | 1998-07-01 | Orlev Scientific Computing Limited | Method of and apparatus for controlling turbulance in boundary layer and other wall-bounded fluid flow fields |
| US20120018021A1 (en) * | 2009-09-30 | 2012-01-26 | The Board Of Trustees Of The University Of Illinois | Vortex generators to control boundary layer interactions |
| TW201225277A (en) * | 2010-02-24 | 2012-06-16 | Osram Opto Semiconductors Gmbh | Method for producing a plurality of optoelectronic semiconductor chips |
| CN103303469A (en) * | 2013-07-05 | 2013-09-18 | 上海交通大学 | Device for controlling flow separation caused by interference between high-Mach-number shock waves and boundary layers |
| JP2015068184A (en) * | 2013-09-27 | 2015-04-13 | 三菱日立パワーシステムズ株式会社 | Steam turbine rotor blade and steam turbine using steam turbine rotor blade |
| CN108303228A (en) * | 2017-08-08 | 2018-07-20 | 北京空天技术研究所 | A kind of boundary layer fluidised form control device and method of wind tunnel test |
| CN112395694A (en) * | 2020-12-03 | 2021-02-23 | 中国人民解放军国防科技大学 | Drag reduction control method for ultrahigh-speed turbulent boundary layer |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107757879B (en) | Wingtip device for a wing of an aircraft, aircraft and use | |
| US8827210B2 (en) | Engine nacelle of an aircraft comprising a vortex generator arrangement | |
| JP2001354198A (en) | Noise reducing device and eddy current generator for main wing of airplane | |
| EP2321084B1 (en) | System and method for aerodynamic flow control | |
| US9132909B1 (en) | Flap edge noise reduction fins | |
| US20150336659A1 (en) | Hypersonic laminar flow control | |
| Desalvo et al. | High-lift enhancement using active flow control | |
| EP1749740B1 (en) | Flow surface for a three-dimensional boundary-layer flow, especially on a swept wing, a swept tail plane or a rotor | |
| US8186619B2 (en) | Airplane engine pylon comprising at least one protruding element to generate a vortex of the airflow | |
| CN109305326B (en) | Wing and aircraft | |
| WO2009106871A2 (en) | Aerodynamic structure with non-uniformly spaced shock bumps | |
| GB2514453A (en) | Cavity acoustic tones suppression | |
| EP0995675B1 (en) | Method for reducing wave resistance in airplane | |
| CN113460284B (en) | Low-Reynolds-number lower wing with inclined grooves | |
| CN115593614A (en) | Hypersonic flow control structure | |
| CN114441134A (en) | Method for inhibiting Mack mode by adopting steady crossflow vortex | |
| CN114148508A (en) | Control device for inhibiting boundary layer interference flow separation | |
| CN214824062U (en) | Grid fusion wing for improving low-speed large-attack-angle flow characteristics | |
| CN211076318U (en) | Vortex generator for reducing resistance of airframe and delaying air flow separation | |
| CN112874756A (en) | Airfoil configuration capable of improving separation characteristic of large attack angle | |
| Eliasson et al. | Improving Stall characteristics of UCAV Wing with Vortex generators | |
| CN206344992U (en) | A kind of tailplane and aircraft of high trim ability | |
| US20190344876A1 (en) | Finlets for aircraft aft-body drag reduction | |
| WO2023065779A1 (en) | Vortex generator, radome, and antenna | |
| Soudakov et al. | Investigations of active and passive flow control on civil aircraft with high-lift configuration |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |