Utafiti huu unachunguza kwa transient computational fluid dynamics (CFD) jinsi flow ndani ya electro-hydraulic thruster (EHT), inayotekeleza release process ya electro-hydraulic brakes, inavyogeuka kuwa vortices na jinsi vortices hizi zinavyoathiriwa na fluid viscosity na motor speed. Researchers wamefafanua three main circulation structures ndani ya EHT zinazoitwa α, β na γ. Kulingana na model results, α na β vortices ni circulations zinazozuia fluid kufikishwa effectively chini ya piston na kusababisha additional energy loss; γ vortex ndiyo main circulation region inayosaidia piston extension. Viscosity ilipoongezeka kutoka 54,5 Pa·s hadi 101,5 Pa·s, peak velocity ya γ vortex ilishuka kutoka 0,39 m/s hadi 0,21 m/s na mean pressure chini ya piston kutoka 0,178 MPa hadi 0,096 MPa. Motor speed ilipoongezeka kutoka 200 rad/s hadi 500 rad/s, peak velocity ya γ vortex iliongezeka kutoka 0,09 m/s hadi 0,58 m/s na mean pressure chini ya piston kutoka 0,0263 MPa hadi 0,435 MPa. Hata hivyo, results hizi zote zinategemea transient CFD simulation; study haitoi physical prototype experiment au field validation.

Initial state ya electro-hydraulic brake ni braking state. EHT motor ikiwa haifanyi kazi, piston iko katika retracted position na spring system inasukuma brake arms kuelekea drum. Brake inapotakiwa kuachiliwa, EHT motor huzungusha impeller; fluid huzungushwa karibu na impeller na guide plate ili kutengeneza pressure chini ya piston. Piston inapoinuka juu, spring force inashindwa na brake arms hufunguka, hivyo brake drum inaachiliwa.

Main finding ya study ni kwamba vortices zote ndani ya EHT hazina function ileile. α vortex iko kati ya sehemu ya juu ya impeller na sehemu ya chini ya guide plate; β vortex katika guide plate na region chini ya piston hurudisha sehemu ya flow kwenye recirculation na kufanya main upward transfer kuwa ngumu. Kwa upande mwingine, γ vortex ndiyo main loop inayoinuka kutoka outer regions hadi chini ya piston na kurudi tena kwenye impeller kupitia center. Kwa hiyo researchers wanatafsiri kuhifadhi γ vortex kama basic requirement kwa EHT brake-release performance.

Viscosity inapoongezeka, absolute peak velocities za vortices zote hupungua; lakini useful γ vortex hudhoofika zaidi. Katika 54,5 Pa·s, α/γ velocity ratio ilikuwa %94,9 na β/γ ratio %64,1; katika 101,5 Pa·s, ratios hizi ziliongezeka hadi %166,7 na %104,8 mtawalia. Increase hii haimaanishi harmful vortices zimekuwa stronger kwa absolute terms; inaonyesha relative dominance yao imeongezeka kwa sababu γ vortex inadhoofika faster.

Kuongeza motor speed kuliziimarisha vortices zote tatu. Hata hivyo, katika range ya 200–500 rad/s, increase ya peak velocity ya γ vortex imehesabiwa katika source kuwa %544,4, wakati increases za α na β ni %169,6 na %173,3 mtawalia. Kwa hiyo high speed inaweza kuimarisha main driving circulation, lakini pia huongeza α na β vortices zinazotengeneza energy loss. Study kwa hiyo haisemi kwamba highest motor speed automatically ndiyo best operating point.

Kwa mtazamo wa Uturuki, study inatoa numerical design framework inayoonyesha kwamba katika industrial mechanisms zinazotumia cranes, lifting na hydraulic brakes, oil viscosity katika low temperature na motor speed zinapaswa kuzingatiwa pamoja. Hata hivyo, viscosity, speed na pressure values zilizoripotiwa zinahusu single EHT geometry na specific CFD assumptions. Katika different brake au thruster design, badala ya kutumia values hizi directly kama set points, experimental au validated numerical analysis inapaswa kufanywa kwenye geometry na fluid ya system husika.

Electro-hydraulic brake inafanyaje kazi?

Electro-hydraulic brake (electro-hydraulic brake, EHB) iliyochunguzwa katika study ilitumika kwenye braking na brake-release mechanism ya fixed-crane-type gate lifting system. System ina electro-hydraulic thruster, spring group, adjustable connecting rod, transmission plate, brake drum, support elements na brake arms mbili.

Katika braking state, EHT motor husimama na piston hurudi ndani. Tensioned spring huvuta transmission mechanism chini na kufunga brake arms mbili kuelekea drum. Hivyo drum hushika lifting shaft na kutengeneza mechanical braking.

Wakati wa brake release, EHT motor hufanya kazi. Impeller huipa fluid kinetic energy na fluid hupelekwa chini ya piston, ikitengeneza upward hydraulic force. Force hii inapotosha, piston hushinda spring force, hujitokeza na brake arms hufunguka pande mbili.

Fluid inafuata njia gani ndani ya EHT?

Three-dimensional model ya EHT ina upper body, piston rod, piston, guide plate, oil reservoir, impeller, lower body na motor components.

Impeller inapozunguka, fluid katika lower region huzunguka circumferentially na pia husogea outward radially. Fluid inayopanda kati ya guide-plate vanes inapofika chini ya piston hutengeneza hydraulic pressure kwenye piston. Flow kisha hurudi chini kupitia central opening hadi juu ya impeller na kutengeneza closed circulation.

Flow hii si one-way pumping motion pekee. Kwa sababu circumferential rotation, radial motion na axial flow zipo kwa wakati mmoja, local recirculations hutokea karibu na guide plate na impeller.

Tofauti kati ya α, β na γ vortices ni nini?

Study imefafanua three different vortex structures:

Classification hii ndiyo important mechanical conclusion ya study. Dhana ya vortex hapa haimaanishi automatically “undesired turbulence”. Ndani ya system ileile, baadhi ya circulations zinachangia hydraulic energy loss, wakati circulation nyingine inachangia kutengeneza functional piston pressure.

Vortices tatu zilitambuliwaje?

Researchers walifafanua three axial monitoring lines kuchunguza pressure na velocity distribution karibu na guide plate.

• Monitoring line 1: axial line inayopita kwenye high-pressure region kati ya guide-plate vanes,
• Monitoring line 2: central axis ya EHT,
• Monitoring line 3: axial line inayopita kwenye low-pressure region kati ya vanes.

Monitoring coordinate iko katika range ya \(Y=4\)–79 mm na imegawanywa katika three regions:

• Region a: \(Y=4\)–25 mm; juu ya impeller na chini ya guide plate,
• Region b: \(Y=25\)–45 mm; kati ya lower na upper surfaces za guide plate,
• Region c: \(Y=45\)–79 mm; juu ya guide plate na chini ya piston.

Ili guide-plate vanes zisikate monitoring line directly, axial lines mbili ziliondolewa 5° kutoka radial direction katika top view.

Pressure distribution inaonyeshaje vortices?

Pressure curves kati ya monitoring line 1 na monitoring line 3 zinaonyesha approximately reciprocal/symmetric variation katika regions a, b na c. Pressure kwenye line 1 kwa ujumla ni higher kuliko line 3. Difference hii inaonyesha kuwepo kwa circulatory flow kati ya points mbili.

Pressure ya central monitoring line 2 kuwa lower kuliko line 1 pia inaonyesha pressure gradient inayosaidia recirculation kutoka outer region kuelekea center.

Karibu na piston base, takriban \(Y=79\) mm, pressures za lines zote tatu zinakaribiana. Katika point ileile, axial velocities hushuka hadi karibu zero. Researchers wanahusisha hili na dynamic pressure ya flow kubadilika zaidi kuwa static pressure chini ya piston na kusaidia piston extension.

Velocity directions zinafafanuaje α vortex?

Katika region a, flow kwenye monitoring line 1 iko katika negative Y direction, huku flow kwenye monitoring line 3 ikiwa katika positive Y direction. Opposite axial velocities pande mbili hutengeneza closed circulation juu ya impeller na chini ya guide plate. Study inafafanua structure hii kama α vortex.

α vortex inahusishwa na flow separation inayotokana na impeller rotation na inatathminiwa kama negative structure kwa sababu haichangii fluid transfer directly hadi chini ya piston.

β vortex inatokea wapi?

Katika regions b na c, directions zinageuka. Wakati fluid kwenye monitoring line 1 inasogea katika positive Y direction, reverse flow ya negative Y direction inatokea kwenye line 3.

Researchers wanaita circulation hii β vortex na kuihusisha na guide-plate vanes kuzuia flow. Circulation hii pia inatafsiriwa kama local energy loss dhidi ya main piston-feeding flow.

Kwa nini γ vortex inachukuliwa kuwa useful?

Kwenye central monitoring line 2, flow katika regions a, b na c iko katika negative Y direction, yaani inarudi kutoka piston region kuelekea impeller. Wakati huo huo, upward flow katika outer regions hutengeneza large closed loop kati ya impeller–guide plate–piston.

Study inafafanua circulation hii kama γ vortex. Kwa sababu γ vortex inatoa continuous fluid supply na pressure chini ya piston, ndiyo main flow structure inayosaidia EHT brake-release function.

CFD model inategemea equations zipi?

Continuity na momentum-conservation equations zilitumika kwa flow field. Kwa incompressible flow, continuity equation imetolewa katika source kama:

\[ \frac{\partial u}{\partial x} + \frac{\partial v}{\partial y} + \frac{\partial w}{\partial z} =0 \]

. Hapa \(u\), \(v\) na \(w\) ni velocity components katika Cartesian coordinates mtawalia.

Momentum equations kwa kila velocity component kwa ujumla zinaunganisha inertia, body-force na viscous-diffusion terms. Kwa mfano, equation katika x direction ni:

\[ \frac{\partial u}{\partial t} + u\frac{\partial u}{\partial x} + v\frac{\partial u}{\partial y} + w\frac{\partial u}{\partial z} = F_x+ \frac{\mu}{\rho} \left( \frac{\partial^2u}{\partial x^2} + \frac{\partial^2u}{\partial y^2} + \frac{\partial^2u}{\partial z^2} \right) \]

. \(F_x\) ni body-force component katika x direction, \(\mu\) dynamic viscosity na \(\rho\) fluid density. Structure ileile ilitumika kwa y na z velocity components.

Kwa nini RNG k-ε turbulence model ilichaguliwa?

Study ilitumia RNG \(k-\varepsilon\) model kwa turbulence. Researchers wanaeleza kwamba model hii inaweza kuwakilisha rotating flow, strong streamline curvature, flow separation na high-strain-rate regions kwa suitability bora kuliko standard \(k-\varepsilon\) model.

Transport equation ya turbulence kinetic energy ni:

\[ \rho_1\frac{\partial k}{\partial t} + \rho_1\frac{\partial}{\partial x_i}(ku_i) = \frac{\partial}{\partial x_j} \left[ \alpha_k(\mu_1+\mu_t) \frac{\partial k}{\partial x_j} \right] + G_k-\rho_1\varepsilon \]

na turbulence dissipation-rate equation ni:

\[ \rho_1\frac{\partial \varepsilon}{\partial t} + \rho_1\frac{\partial}{\partial x_i}(\varepsilon u_i) = \frac{\partial}{\partial x_j} \left[ \alpha_\varepsilon(\mu_1+\mu_t) \frac{\partial \varepsilon}{\partial x_j} \right] + C_{1\varepsilon}\frac{\varepsilon}{k}G_k - C_{2\varepsilon}\rho_1\frac{\varepsilon^2}{k} \]

.

Katika source, model coefficients zilitumika kama:

• \(C_{1\varepsilon}=1,42\)
• \(C_{2\varepsilon}=1,68\)

.

Numerical solution ilifanywa chini ya conditions zipi?

Transient CFD analyses zilifanywa katika ANSYS Fluent 2021 R1. Pressure-based implicit solver ilitumika, pamoja na SIMPLE algorithm kwa pressure-velocity coupling. Transport terms za turbulence kinetic energy na dissipation rate zili-discretize kwa second-order upwind scheme.

Ni fluid values zipi zilitumika kwa temperature?

Values hizi zimehifadhiwa kwa units na numbers zilizotolewa katika source. Study inawakilisha low-temperature context kwa conditions hizi tatu; parametric CFD table haina temperature point chini ya 0 °C.

Mesh independence ilikaguliwaje?

EHT flow volume ilimeshiwa kwa polyhedral elements. Impeller, lower impeller connection region na guide-plate vanes zilirefined locally.

Researchers walieleza kwamba result differences zilikuwa chini ya %0,35 na wakatumia mesh yenye elements 5.270.888 katika final analyses ili kupunguza computational load.

Nini hutokea viscosity inapoongezeka?

Viscosity inapoongezeka kutoka 54,5 Pa·s hadi 101,5 Pa·s, peak velocities za vortices zote tatu hupungua. Hata hivyo, reduction hii si equal.

Reduction rates zilizotolewa katika source ni %5,4 kwa α, %12,0 kwa β na %46,2 kwa γ. Kwa hiyo high viscosity hudhoofisha pia α na β vortices zinazochukuliwa harmful; lakini inasuppress γ vortex inayochangia piston drive kwa kiwango kikubwa zaidi.

Kwa hiyo α/γ na β/γ ratios huongezeka. Kuongezeka kwa relative ratios hakumaanishi absolute velocities za α na β zimeongezeka; kunatokana na γ kudhoofika faster.

Source inajipinga wapi kuhusu viscosity?

Abstract ya article inasema higher viscosity inaongeza vortex development na pressure fluctuation. Kinyume chake, Section 4.1 inaonyesha kwamba pressure-fluctuation amplitude hupungua na viscosity na peak velocities za vortices zote tatu pia hushuka. Discussion section pia inaeleza kwamba high viscosity inasuppress vortices zote.

Kwa hiyo, kwa kuzingatia numerical tables na detailed results section, statement inayoungwa mkono ni hii: viscosity increase hupunguza absolute vortex velocities, lakini hudhoofisha useful γ vortex proportionally zaidi na hupunguza pressure chini ya piston. Opposite statement katika abstract inapaswa kuhifadhiwa kama source-internal inconsistency.

Kuongeza motor speed kunafanya nini?

Motor speed ilianalizwa katika levels za 200, 300, 400 na 500 rad/s. Speed inapoongezeka, pressures na pressure differences kwenye monitoring lines tatu ziliongezeka na peak velocities za vortices zote zilipanda.

Source inaripoti increase ya α vortex peak velocity katika 200–500 rad/s kuwa %169,6, β kuwa %173,3 na γ kuwa %544,4. Kwa hiyo relative weight ya γ huongezeka speed inapoongezeka: α/γ ratio hushuka kutoka %255,6 hadi %106,9, na β/γ ratio kutoka %166,7 hadi %70,7.

Hata hivyo, motor-speed increase haiondoi α na β. Kinyume chake, absolute velocities za harmful vortices hizi mbili pia huongezeka. Kwa hiyo engineering interpretation ya study si “ongeza motor speed kadiri iwezekanavyo”, bali kubaini suitable speed range kati ya brake-release force na hydraulic energy loss.

Viscosity na motor speed zinapaswa kutafsiriwaje pamoja?

Numerical results za study zinaonyesha two different regulation mechanisms. Viscosity inapoongezeka, viscous friction na flow resistance huongezeka na circulations zote hudhoofika. Lakini kwa sababu γ hudhoofika faster, piston-driving capability huathiriwa negatively.

Motor speed inapoongezeka, kinetic energy na pressure gradient zinazoingizwa kwenye system huongezeka na vortices zote tatu huimarika. Kwa sababu growth rate ya γ vortex ni higher, piston pressure inaboreshwa; lakini energy loss kutokana na α na β pia huongezeka.

Source inapendekeza parameters hizi mbili zichaguliwe kwa kuendana na temperature, load na response time. Hata hivyo, article haitoi separate two-factor interaction analysis inayoscan all combinations za viscosity na speed katika same experimental matrix.

Matokeo yanayoungwa mkono na utafiti

• Katika transient CFD model ya EHT geometry iliyochunguzwa, three different circulation structures ziliainishwa kama α, β na γ.
• α na β vortices zilitathminiwa kama structures zinazozuia main piston-feeding flow na kuhusishwa na additional hydraulic energy loss.
• γ vortex ilitambuliwa kama main circulation inayochangia pressure formation chini ya piston.
• Katika viscosity range ya 54,5–101,5 Pa·s, peak velocities za vortices zote tatu zilipungua; reduction ya γ vortex iliripotiwa kuwa %46,2 katika source.
• Katika viscosity change ileile, mean pressure chini ya piston ilishuka kutoka 0,178 MPa hadi 0,096 MPa.
• Katika motor-speed range ya 200–500 rad/s, vortices zote tatu ziliimarika; increase ya γ vortex peak velocity iliripotiwa kuwa %544,4.
• Katika speed range ileile, mean pressure chini ya piston iliongezeka kutoka 0,0263 MPa hadi 0,435 MPa.
• Katika mesh-independence check, under-piston pressure result ya selected mesh yenye elements 5.270.888 ilipatikana close na denser meshes.

Matokeo ambayo utafiti hauungi mkono au haujatesti

• CFD results hazijavalidated experimentally kwa physical EHT prototype.
• Study haitoi brake-release time au reliability test katika real field conditions.
• Result sensitivity ya RNG k-ε model dhidi ya other turbulence models haijatestwa.
• Cavitation effect haijajumuishwa katika model.
• Temperature gradients ndani ya fluid hazijasolved.
• Manufacturing tolerances, assembly clearances na component wear hazijajumuishwa katika model.
• Three viscosity points na 200–500 rad/s speed range haziwakilishi all EHT operating conditions.
• Source haitoi single universal optimum motor speed.
• Source haijafafanua universal optimum viscosity inayotumika kwa all EHT designs.
• Full factorial interaction analysis inayojumuisha all combinations za viscosity na motor speed haijawasilishwa.

Mbinu na Matokeo ya Utafiti

EHT geometry na flow structure

Main components za EHT iliyotumika katika study ni upper body, piston rod, piston, guide plate, oil reservoir, impeller, lower body na electric motor. Impeller inaaccelerate fluid katika circumferential na radial directions, guide plate inaelekeza flow chini ya piston, na central region inatengeneza return path.

Main purpose ya CFD model si kusolve mechanical motion ya piston kama complete multiphysics model, bali kuchunguza pressure na velocity characteristics za internal flow field wakati wa brake-release process na transformation yake kuwa vortices.

Fluid boundary conditions

Katika main reference solution ya source, density ya 866 kg/m³, viscosity ya 76,5 Pa·s na impeller speed ya 300 rad/s zimetumika.

Numerical-solver settings

Mesh-independence test

Study ilichagua model yenye elements 5.270.888 inayolingana na 2,0 mm characteristic mesh size kwa final calculations.

Viscosity-dependent vortex results

Table hii inaonyesha kwamba high viscosity haisuppress harmful vortices completely; inadhoofisha vortices zote tatu na γ ndiyo circulation inayodhoofika zaidi.

Motor-speed-dependent vortex results

Kuongeza motor speed kuliimarisha useful γ circulation kwa relative rate kubwa zaidi; lakini absolute velocities za α na β vortices pia ziliongezeka. Kwa hiyo result inaonyesha si advantage ya high speed pekee, bali optimization problem kati ya drive na energy loss.

Response ya pressure chini ya piston kwa two main parameters

Katika numerical model, high viscosity ilipunguza pressure chini ya piston huku high motor speed ikiongeza pressure chini ya piston. Results hizi zinatumika only kwa EHT geometry iliyochunguzwa na defined CFD conditions.

Main model assumptions na limits za study

• Geometry ni fixed; manufacturing na assembly tolerances hazijazingatiwa.
• Component wear haijamodeled.
• Cavitation haijajumuishwa katika model.
• Temperature gradients ndani ya fluid hazijasolved.
• Boundary disturbances zote hazijamodeled.
• Only RNG k-ε turbulence model imetumika.
• Hakuna validation kwa experimental PIV, pressure sensor au prototype test.
• Wall na vortex-core resolution zinalimitiwa na computational resources.

Nini kinapendekezwa kama future work?

Researchers wanapendekeza prototype experiments, comparison ya different turbulence models, adaptive mesh refinement na examination ya broader viscosity/speed parameter ranges katika future work. Vipengele hivi si results zilizotekelezwa katika current study, bali ni future validation steps.

Maelezo ya Chanzo na Mbinu

Jina kamili asilia la utafiti: Research on the Formation Mechanism of Vortices and Key Parameter Regulation in the Electro-Hydraulic Thruster

Waandishi: Yanan Sun, Zezheng Tian, Na Li, Haiyong Jiang, Chao Yang, Chongchong Chen, Lei Yang, Lei Xing, Lijie Zhang.

Author order: Order katika source imehifadhiwa exactly.

Corresponding author: Lijie Zhang.

Equal contribution/co-first author: Hakuna statement kama hiyo katika source.

Taasisi: College of Mechatronical & Electrical Engineering, Hebei Agricultural University, Baoding, China; Hebei Province Intelligent Agricultural Equipment Technology Innovation Center, Baoding, China.

Jarida: Machines.

Mchapishaji: MDPI.

Bibliographic record: Machines 2026, 14, 669.

DOI: 10.3390/machines14060669.

Official publication link:https://doi.org/10.3390/machines14060669

Publication date: 8 June 2026.

Source type na peer-review status: Ni peer-reviewed original research article. Scientific findings zinategemea transient CFD simulations; physical prototype validation haikufanywa.

Leseni: Creative Commons Attribution (CC BY).

Funding: Study iliungwa mkono kwa sehemu na Hebei Province Innovation Team of Modern Agricultural Industry Technology System (HBCT2024050206), Hebei Province Major Science and Technology Support Program Project (242N1901Z), Hebei Province Agricultural Science and Technology Achievement Transformation Fund Project (2025JNZ-S19), na basic scientific research expenses project ya universities za Hebei Province (KY2025044).

Data availability: Imeelezwa kwamba original simulation data, mesh files na model-parameter files zinaweza kutolewa na corresponding author upon reasonable request.

Conflict of interest: Imeelezwa kwamba Yanan Sun, Na Li, Haiyong Jiang, Chao Yang, Chongchong Chen, Lei Yang na Lijie Zhang wanafanya kazi ndani ya Hebei Province Intelligent Agricultural Equipment Technology Innovation Center. Waandishi wanaripoti kwamba study ilifanywa bila commercial au financial relationship.

Author contributions: Yanan Sun methodology, investigation na formal analysis; Zezheng Tian ANSYS Fluent 2021 R1 software na formal analysis; Na Li review/editing na project administration; Haiyong Jiang methodology na validation; Chao Yang visualization na data curation; Chongchong Chen formal analysis; Lei Yang validation; Lei Xing resources; Lijie Zhang supervision na conceptualization.

EHB/EHT operating principle, flow-field explanations, equations, CFD conditions, mesh-independence data, vortex classification, viscosity na motor-speed results, pamoja na limitations katika Verianla article hii zinategemea source study iliyochunguzwa. Hakuna new scientific experiment, mechanism au numerical result kutoka external sources iliyoongezwa isipokuwa bibliographic identity verification.

Main methodological boundary: Study haikufanya physical EHT prototype test, field measurement au validation kwa published experimental data. Only RNG k-ε turbulence model ilitumika na turbulence-model sensitivity haikuchunguzwa. Cavitation, fluid-temperature gradient, manufacturing tolerances, assembly clearances, wear na baadhi ya transient boundary disturbances hazijajumuishwa katika model.

Source-internal inconsistency note: Abstract ya article inasema high viscosity inaongeza vortex development na pressure fluctuation. Kinyume chake, detailed Section 4.1, Table 3 na Discussion section zinasema peak velocities za vortices zote tatu hupungua na pressure-fluctuation amplitude hupungua viscosity inapoongezeka. Katika Verianla article, statements hizi mbili hazijaunganishwa kimya kimya; numerical results na source-internal verbal inconsistency zimehifadhiwa separately.

Parametric-interaction boundary: Ingawa source abstract inataja independent na combined effects za viscosity na motor speed, main parametric results zilizowasilishwa zinajumuisha analyses zinazobadilisha variables hizi mbili separately. Full two-factor interaction matrix au statistical coupling test haijawasilishwa.

Unit note: Dynamic viscosity imetolewa katika source kama 54,5; 76,5 na 101,5 Pa·s. Values hizi zimehifadhiwa kwa unit ileile kwa source fidelity.