CN106545522A - A kind of special blade of propeller fan - Google Patents
A kind of special blade of propeller fan Download PDFInfo
- Publication number
- CN106545522A CN106545522A CN201710033538.6A CN201710033538A CN106545522A CN 106545522 A CN106545522 A CN 106545522A CN 201710033538 A CN201710033538 A CN 201710033538A CN 106545522 A CN106545522 A CN 106545522A
- Authority
- CN
- China
- Prior art keywords
- circular arc
- blade
- arc camber
- propeller fan
- chord length
- 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
- 230000003247 decreasing effect Effects 0.000 claims abstract description 9
- 238000005516 engineering process Methods 0.000 abstract description 9
- 238000004134 energy conservation Methods 0.000 abstract 1
- 238000013461 design Methods 0.000 description 13
- 230000005611 electricity Effects 0.000 description 5
- 238000000034 method Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 241000826860 Trapezium Species 0.000 description 1
- 230000003321 amplification Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 230000021715 photosynthesis, light harvesting Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/26—Rotors specially for elastic fluids
- F04D29/32—Rotors specially for elastic fluids for axial flow pumps
- F04D29/38—Blades
- F04D29/388—Blades characterised by construction
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/26—Rotors specially for elastic fluids
- F04D29/32—Rotors specially for elastic fluids for axial flow pumps
- F04D29/38—Blades
- F04D29/384—Blades characterised by form
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
- F04D29/661—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps
- F04D29/663—Sound attenuation
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
- F04D29/661—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps
- F04D29/666—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps by means of rotor construction or layout, e.g. unequal distribution of blades or vanes
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
Abstract
The invention discloses a kind of special blade of propeller fan, belong to blade technology field, including blade face and petiole, the blade face is combined successively by some circular arc cambers, each circular arc camber has corresponding chord length, the chord length of some circular arc cambers is successively decreased successively, and the wherein most long circular arc camber of chord length is connected with the petiole.The characteristics of present invention has efficiency high, little noise and energy-conservation.
Description
Technical field
The invention belongs to the special blade technology field of ventilation blower, and in particular to a kind of special blade of propeller fan.
Background technology
The pneumatic property of axial fan impeller is the principal element for determining fan performance quality, and the section shape of impeller blade
Shape is the key for determining fan performance again.There are many middle shapes in relevant document, most important of which is no more than using in aviation
Aircraft wing aerofoil profile；As condition is limited, other fields or industry are not put into or less input for the research of aerofoil profile,
The best use of of aerofoil profile can not be given full play to as fan impeller blade shape using the existing aerofoil profile of aviation usually.Generally
Using the advanced pneumatic design analytical technology on science and technology of aviation, for the use condition of blower fan, the special wing of serial fan is designed
Type, is proved by wind tunnel test, and the performance of new aerofoil is higher than original aerofoil profile.It is Reynolds system that aerofoil profile starts the Main Basiss of design
Number, it is generally considered that Reynolds number is than relatively low, it is therefore possible to require to keep longer distinguished and admirable section on aerofoil profile aerofoil, to reduce resistance
Power, improves lift-drag ratio.
In existing design, although wing blades are a lot, which uses the efficiency in blower fan to fail to get a promotion, and makes an uproar
Sound is larger, and takes electricity, uses very inconvenient.
The content of the invention
The technical problem to be solved in the present invention is to provide that a kind of efficiency high, noise be few, function admirable propeller fan is special
Use blade.
To reach above-mentioned purpose, technical scheme is as follows：
A kind of special blade of propeller fan, including blade face and petiole, the blade face is combined successively by some circular arc cambers
Form, the chord length that each circular arc camber there are corresponding chord length, some circular arc cambers is successively decreased successively, the wherein most long circular arc of chord length is bent
Face is connected with the petiole.
In a preferred embodiment of the invention, the blade face is first subtracted the circular arc camber group for increasing afterwards by least seven sections arc length
Conjunction is formed.
In a preferred embodiment of the invention, the circular arc camber group that the blade face (1) is successively decreased successively by seven sections of chord lengths
Conjunction is formed；Between seven sections of circular arc cambers, the length ratio of string is 150-240:140-230:130-210：125-200:120-
195:115-190:110-180。
In a preferred embodiment of the invention, every section of circular arc camber is equipped with maximum gauge, and seven sections of circular arcs are bent
The maximum gauge ratio in face is 13-29：11-26:9-23:7-21:6-19:5-17:4-16.
In a preferred embodiment of the invention, the petiole is provided with the mounting plane being connected with the blade face, described
In blade face, the most long circular arc camber of chord length forms angle with the mounting plane, and the angle is 30 ° -50 °.
In a preferred embodiment of the invention, the most short circular arc camber of chord length and the mounting plane in the blade face
Angle is formed, the angle is 7 ° -20 °.
In a preferred embodiment of the invention, in seven sections of circular arc cambers, circular arc of the chord length in most intermediate value
Curved surface forms 13 ° -28 ° of angle with the mounting plane.
In a preferred embodiment of the invention, the petiole is column type or ladder type.
In a preferred embodiment of the invention, the circular arc camber that some chord lengths are successively decreased successively is integrally formed described
Blade face.
By above-mentioned technical proposal, the invention has the beneficial effects as follows：
The present invention is adopted based on Isolated Airfoil method by arranging rational short fluid layer, is used for reference and is absorbed Pneumatic fan
It is designed with the blower fan engineering design system of the design philosophy and method of properller, effectively increases fan blade and be applied to wind
Efficiency in machine.
The present invention is applied in blower fan, compares traditional blower fan, and efficiency improves 10%-35%, lower noise 3-10 decibels,
Economize on electricity 10-20%, in its application, more existing blower fan, efficiency are increased substantially, and noise is substantially reduced, and advanced technology, performance are excellent
It is good.
Description of the drawings
In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
Accompanying drawing to be used needed for having technology description is briefly described, it should be apparent that, drawings in the following description are only this
Some embodiments of invention, for those of ordinary skill in the art, on the premise of not paying creative work, can be with
Other accompanying drawings are obtained according to these accompanying drawings.
A kind of front view of embodiment that Fig. 1 is provided for the present invention；
A kind of top view of embodiment that Fig. 2 is provided for the present invention；
A kind of right view of embodiment that Fig. 3 is provided for the present invention；
The front view of another kind of embodiment that Fig. 4 is provided for the present invention；
The top view of another kind of embodiment that Fig. 5 is provided for the present invention；
The right view of another kind of embodiment that Fig. 6 is provided for the present invention；
Numeral and the corresponding component title represented by letter in figure：
1, blade；101st, the first circular arc camber；102nd, the second circular arc camber；103rd, three-arc curved surface；104th, the 4th circle
Arc surface；105th, the 5th circular arc camber；106th, the 6th circular arc camber；107th, the 7th circular arc camber；2nd, petiole.
Specific embodiment
In order that technological means, creation characteristic, reached purpose and effect that the present invention is realized are easy to understand, tie below
Conjunction is specifically illustrating, and the present invention is expanded on further.
Embodiment 1
Referring to the drawings shown in 1-3, the special blade of a kind of propeller fan that the present invention is provided, including blade face 1 and petiole 2,
The blade face 1 includes that some circular arc cambers are combined successively, and each circular arc camber has corresponding chord length, some circular arc cambers
Chord length is successively decreased successively, and the wherein most long circular arc camber of chord length is connected with the petiole.
Wherein, circular arc camber is specially aerofoil profile.
In above-mentioned blade face 1, the overall arc curve on blade face 1 be first grow after short long again, i.e., some circular arc cambers on blade face 1
In, the arc length of circular arc camber is short to a certain degree first gradually to shorten from most long, then elongated again.Some circular arc camber shapes
Into a relative blade face 1 for having warp surface.
Wherein petiole 2 is trapezium structure.
In above-described embodiment, due to based on Isolated Airfoil method so that whole blade face keeps longer laminar flow section, and then
Resistance is reduced, lift-drag ratio is improve, is applied in blower fan, compared with existing blower fan, its efficiency is carried than conventional fan efficiency
It is high 20%, 5 decibels of lower noise, economize on electricity reaches 15%, and then improves the life-span of product.
Embodiment 2
Referring to the drawings shown in 4-6, the special blade of a kind of propeller fan, including blade face 1 and petiole 2, the blade face 1 is by seven
Section circular arc camber is combined successively, including the first circular arc camber 101, the second circular arc camber 102, three-arc curved surface 103, the
Four circular arc cambers 104, the 5th circular arc camber 105, the 6th circular arc camber 106 and the 7th circular arc camber 107, each circular arc camber have
Corresponding chord length, the chord length of some circular arc cambers are successively decreased successively, and the wherein most long circular arc camber of chord length is connected with the petiole 2.
Wherein petiole 2 is cylindrical structural.
Wherein circular arc camber is specially aerofoil profile.
In use, the chord length of seven sections of circular arc cambers is reduced successively, and the chord length ratio of seven sections of circular arc cambers is：206：190：
180：170：166：162：160.
Wherein, the generally curved surface of blade face 1, and the curved surface is provided with certain thickness, every section of circular arc camber is equipped with thickness,
And the thickness of every section of circular arc camber has maximum gauge, and seven sections of maximum gauge value ratio is 23：20：17：15：13：12：
11。
Seven sections of circular arc camber its chord lengths are followed successively by the first circular arc camber 101, the second circular arc camber the 102, the 3rd from big to small
Circular arc camber 103, the 4th circular arc camber 104, the 5th circular arc camber 105, the 6th circular arc camber 106 and the 7th circular arc camber 107,
In the petiole 2 of arc-shaped structure, the uppermost face of cylindrical structural is connection plane, and connection plane is connected with the blade face 1, its
In the first circular arc camber 101 and it is described connection plane formed 44 ° of angles, the 4th circular arc camber 104 with it is described connection plane formed
23 ° of angles, the 7th circular arc camber 107 form 15 ° of angles with the connection plane.
Referring to the drawings, wherein b is the 7th circular arc camber 107 and the angle for being connected plane formation
Due to the restriction of above-mentioned seven crucial circular arc cambers so that the air quantity of whole blade is changed, and is applied to wind
In machine, its performance gets a promotion relative to existing blower fan, efficiency raising 12%, 8 decibels of lower noise, economize on electricity 10%.It is actual
In structure, seven continuous circular arc cambers sequentially form a blade face 1, conveniently can produce.
, by analyzing Reynolds number, the principle designed using aerodynamic, appropriate design structure, equitable subsection are thick for the present invention
Degree is reasonably changed, and improves whole service efficiency, for blower fan field is a kind of very big progress.
The present invention is applied in practice, and efficiency improves 10%-35% than traditional blower fan, lower noise 3-10 decibels,
Economize on electricity 10-20%, in its application, more existing blower fan, efficiency are increased substantially, and noise is substantially reduced, and advanced technology, performance are excellent
It is good.
Embodiment 3
The present invention is used in practice, according to the specification of different type of machines, needs to design different chord lengths etc..Below table is given
The blade specification of 14 kinds of different type of machines is gone out, concrete table 1 is chord data, and table 2 is section aerofoil profile maximum gauge (mm) and installation
Angle, specially：
Table 1
Table 2
In above table, data are design data, and the product amplification shrinkage factor of actual production is ± 5% scope, these
Belong to protection scope of the present invention.
Above table is the fan blade of 14 kinds of different models in actual production, and which is applied in blower fan with traditional blades
Contrasted, fan efficiency is improved, noise obtains link, while power consumption is minimized.
Under blower fan use condition, Reynolds number that air viscosity affects is embodied than relatively low, blade is generally in low speed, high-lift
Run under coefficient.When but Reynolds number is relatively low, it is possible to require that the aerofoil of airfoil fan keeps longer laminar flow section, to reduce
Resistance, improves lift-drag ratio；But long laminar flow section, can make performance depreciation of the aerofoil profile under off design point.Design lift system
Number is 0.5-0.7, and its numeric ratio is larger, in order that the upper and lower airfoil portion of aerofoil profile keeps longer laminar flow section, aerofoil profile have suitable
When camber, favourable aerofoil pressure distribution could be obtained, be conducive to keeping Laminar Flow, and then the effect of blower fan can be lifted
Rate.In the application, as blade includes multiple circular arc cambers, and each face thickness, chord length, direct etc. are different, thus result in
Blade is provided with multiple laminar flow sections, and the length of each laminar flow section is variable, while overall blade face has certain camber, improves leaf
Piece efficiency.
In the application, according to blade design principle, the aerodynamic configuration of blade on the cross section of blade, can be seen, which can be with
Producing thrust promotes blower fan to rotate；Meanwhile, the aerofoil profile of the application, it is ensured that air-flow will not produce flow-disturbing excessively slowly by blade, together
When also will not be too fast by speed, do not result in energy dissipation.The thickness of the application design profile, can improve catch wind efficiency.
And blade is integrally distorted, and then Windward angle persistently changes, and region has the optimal angle of attack windward to maintain blade, not only
The principle of aerodynamic design is met, and its efficiency has been improved also because the aerofoil profile details of distortion angle, thickness and blade
Fan efficiency, reduces noise pollution.
The ultimate principle and principal character and advantages of the present invention of the present invention has been shown and described above.The technology of the industry
Personnel it should be appreciated that the present invention is not restricted to the described embodiments, the simply explanation described in above-described embodiment and description this
The principle of invention, without departing from the spirit and scope of the present invention, the present invention also has various changes and modifications, these changes
Change and improvement is both fallen within scope of the claimed invention.The claimed scope of the invention by appending claims and its
Equivalent thereof.
Claims (9)
1. the special blade of a kind of propeller fan, including blade face (1) and petiole (2), it is characterised in that：The blade face (1) if by
Dry circular arc camber is combined successively, and the chord length that each circular arc camber has corresponding chord length, some circular arc cambers is successively decreased successively, its
The most long circular arc camber of middle chord length is connected with the petiole.
2. the special blade of a kind of propeller fan according to claim 1, it is characterised in that：The blade face (1) is by least
The circular arc camber that seven sections of chord lengths are successively decreased successively is combined.
3. the special blade of a kind of propeller fan according to claim 2, it is characterised in that：The blade face (1) is by seven sections
The circular arc camber that chord length is successively decreased successively is combined；Between seven sections of circular arc cambers, the length ratio of string is 150-240:140-
230:130-210：125-200:120-195:115-190:110-180.
4. the special blade of a kind of propeller fan according to claim 3, it is characterised in that：Every section of circular arc camber is equipped with
Maximum gauge, the maximum gauge ratio of seven sections of circular arc cambers is 13-29：11-26:9-23:7-21:6-19:5-17:4-
16。
5. the special blade of a kind of propeller fan according to claim 3, it is characterised in that：The petiole (2) be provided with
The mounting plane that the blade face (1) connects, in the blade face (1), the most long circular arc camber of chord length is formed with the mounting plane
30 ° -50 ° of angle.
6. the special blade of a kind of propeller fan according to claim 5, it is characterised in that：Chord length in the blade face (1)
Most short circular arc camber forms 7 ° -20 ° of angle with the mounting plane.
7. the special blade of a kind of propeller fan according to claim 5, it is characterised in that：Seven sections of circular arc cambers
In, circular arc camber of the chord length in most intermediate value forms 13 ° -28 ° of angle with the mounting plane.
8. according to a kind of arbitrary described special blade of propeller fan of claim 1-7, it is characterised in that：The petiole (2)
For column type or ladder type.
9. the special blade of a kind of propeller fan according to claim 8, it is characterised in that：Some chord lengths are passed successively
The circular arc camber for subtracting is integrally formed the blade face (1).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710033538.6A CN106545522A (en) | 2017-01-16 | 2017-01-16 | A kind of special blade of propeller fan |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710033538.6A CN106545522A (en) | 2017-01-16 | 2017-01-16 | A kind of special blade of propeller fan |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN106545522A true CN106545522A (en) | 2017-03-29 |
Family
ID=58398591
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710033538.6A Pending CN106545522A (en) | 2017-01-16 | 2017-01-16 | A kind of special blade of propeller fan |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN106545522A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107013489A (en) * | 2017-04-07 | 2017-08-04 | 陕西金翼通风科技有限公司 | A kind of novel impeller and its installation method |
| CN107100892A (en) * | 2017-04-07 | 2017-08-29 | 陕西金翼通风科技有限公司 | A kind of axial fan blade |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040062654A1 (en) * | 2002-09-27 | 2004-04-01 | Delta Electronics, Inc. | Axial flow fan with multiple segment blades |
| CN202360461U (en) * | 2012-04-01 | 2012-08-01 | 北京新安特风机有限公司 | Blade structure of fan |
| CN204061320U (en) * | 2014-07-28 | 2014-12-31 | 北京新安特风机有限公司 | A kind of axial-flow blower single plate blade structure |
| CN205331054U (en) * | 2016-01-29 | 2016-06-22 | 邯郸市东方风机制造有限公司 | Axial -flow fan with many curved surfaces type blade |
| CN206397815U (en) * | 2017-01-16 | 2017-08-11 | 陕西金翼通风科技有限公司 | A kind of special blade of propeller fan |
-
2017
- 2017-01-16 CN CN201710033538.6A patent/CN106545522A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040062654A1 (en) * | 2002-09-27 | 2004-04-01 | Delta Electronics, Inc. | Axial flow fan with multiple segment blades |
| CN202360461U (en) * | 2012-04-01 | 2012-08-01 | 北京新安特风机有限公司 | Blade structure of fan |
| CN204061320U (en) * | 2014-07-28 | 2014-12-31 | 北京新安特风机有限公司 | A kind of axial-flow blower single plate blade structure |
| CN205331054U (en) * | 2016-01-29 | 2016-06-22 | 邯郸市东方风机制造有限公司 | Axial -flow fan with many curved surfaces type blade |
| CN206397815U (en) * | 2017-01-16 | 2017-08-11 | 陕西金翼通风科技有限公司 | A kind of special blade of propeller fan |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107013489A (en) * | 2017-04-07 | 2017-08-04 | 陕西金翼通风科技有限公司 | A kind of novel impeller and its installation method |
| CN107100892A (en) * | 2017-04-07 | 2017-08-29 | 陕西金翼通风科技有限公司 | A kind of axial fan blade |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US9951749B2 (en) | System and method for trailing edge noise reduction of a wind turbine blade | |
| CN103277245B (en) | Large-thickness blunt-trailing-edge wind-power airfoil profiles and a design method thereof | |
| CN103485973B (en) | A kind of pneumatic equipment blades with tip vane | |
| CN109110124A (en) | A kind of new Main Rotor Blade | |
| CN104564804B (en) | Wind wheel blade, cross-flow wind wheel and design method of wind wheel blade | |
| CN102003332B (en) | Blade airfoil family of wind turbine | |
| CN109229364B (en) | Class ellipse aerofoil profile applied to high-speed helicopter rotor reversed flow region | |
| CN106545522A (en) | A kind of special blade of propeller fan | |
| CN107933895A (en) | It is a kind of to blow structures and methods for the micro- of supercritical airfoil drag reduction lift-rising | |
| CN106428551A (en) | Multi-rotor blade device | |
| CN206397815U (en) | A kind of special blade of propeller fan | |
| CN200978778Y (en) | Windwheel blade for small-sized wind-driven generator | |
| CN103939392B (en) | Axial flow fan blade and air conditioner with same | |
| CN103133272A (en) | Thin airfoil type blade of large-scale fan | |
| CN206785724U (en) | A kind of axial fan blade | |
| CN211737550U (en) | Backward centrifugal cross-section noise reduction type centrifugal fan blade | |
| CN107100892A (en) | A kind of axial fan blade | |
| CN105787217B (en) | A kind of optimum design method of aircraft ripple aerofoil profile | |
| CN203161650U (en) | Axial flow fan blade and air conditioner with same | |
| CN203321756U (en) | Medium-thickness airfoil blade for large turbines | |
| CN112814943A (en) | Integrally formed curved and swept combined blade, impeller and axial flow fan | |
| CN106762829A (en) | blade for impeller, impeller and fan | |
| CN203175769U (en) | Thin wing type blade of large-scale fan | |
| CN206929131U (en) | Axial flow blower 3 d impeller with leaf vein texture and non-homogeneous empennage | |
| CN203770214U (en) | Large axial flow fan impeller with wing flaps |
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 | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20170329 |