CN104850737A - Thermal analysis method for plunger pump in less-cooling hydraulic system - Google Patents

Abstract

The present invention discloses a thermal analysis method for a plunger pump in a less-cooling hydraulic system, and belongs to the field of thermal conduction of the hydraulic system. According to the present invention, a centralized parameter method is utilized to establish a five-temperature-node thermal analysis model of the plunger pump in the less-cooling hydraulic system and establish a thermal balance equation of five temperature nodes; an accurate leakage rate model of the plunger pump is established; and a dynamic viscosity parameter of circulating oil in the less-cooling hydraulic system is calculated, a dynamic accurate leakage rate related to the temperature of the oil is obtained and is substituted into the thermal balance equation so as to obtain temperature of each temperature node. By introducing conversion temperature nodes, the thermal analysis method disclosed by the present invention solves the problem that when a common thermal analysis method for the plunger pump in the hydraulic system is used for solving the thermal analysis problem of the plunger pump in the less-cooling hydraulic system, a calculating result is greatly deviated due to ignorance of the condition that viscosity of the oil is influenced by the temperature rising to be reduced and the leakage rate is therefore changed.

Description

A kind of heat analysis method for ram pump in deficient liquid coolant pressing system

Technical field

The present invention relates to hydraulic system heat transfer field, be specifically related to a kind of heat analysis method for ram pump in deficient liquid coolant pressing system.

Background technology

Along with the development of power-by-wire technology, be that the distributed hydraulic actuation system of representative is widely adopted aboard with Electrical hydrostatic actuator.Compare with traditional Centralized Hydraulic System, distributed hydraulic system uses electric energy as the transmission mode of energy, therefore the supply reservoir concentrated and the pipeline road spreading all over fuselage is not needed, these changes alleviate the weight of aircraft, avoid and are brought the problems such as vibration, noise by pipeline road.But do not have centralized oil supply fuel tank, recycle oil is short out, make fluid not have enough area of dissipations to dispel the heat at circulation time, this just causes distributed hydraulic system operationally, and under the state being in a kind of deficient cooling, therefore it is a kind of deficient liquid coolant pressing system.

Owing to can produce larger fluid temperature rise when deficient liquid coolant pressing system runs, and too high oil temperature can affect the normal work of hydraulic system, even causes the system failure and inefficacy.In deficient liquid coolant pressing system, need the heat loss through convection coefficient by such as strengthening environment, the means such as the area of dissipation of oil circuit solve the too high problem of fluid temperature rise.Therefore, in the design of deficient liquid coolant pressing system, needing to add thermal design link, and look for suitable heat analysis method, is the prerequisite of deficient liquid coolant pressing system being carried out to thermal design.

In the device forming hydraulic system, it is hydraulic energy that ram pump is responsible for changes mechanical energy, is of paramount importance power conversion apparatus.Simultaneously due to the power loss in power conversion process, make the heat generating device that ram pump becomes main in hydraulic system.Therefore, find suitable heat analysis method, thermal analyses is carried out to the ram pump in deficient liquid coolant pressing system, for the thermal analyses of deficient liquid coolant pressing system entirety and thermal design, just become particularly important.

The current heat analysis method for ram pump the ram pump be not suitable in deficient liquid coolant pressing system.Reason is: 1. general heat analysis method when carrying out ram pump thermal analyses, and reckons without the feature that deficient liquid coolant pressing system oil circuit is short, area of dissipation is little, thinks that the oil liquid temperature that ram pump sucks is constant value; 2. leaking is the main cause causing power of plunger pump to lose, and power loss is the main cause of ram pump heat-dissipating, the therefore heat-dissipating of leakage rate direct relation ram pump.Leakage rate, when processing this problem, is often thought a constant value by ram pump heat analysis method in the past, and this is not inconsistent with the ram pump characteristic of owing in cooling hydraulic pressure system.For deficient liquid coolant pressing system, at its operational process, fluid temperature rise is larger.The change of temperature can make oil viscosity change, and these changes can have an impact to ram pump leakage rate, and then affect ram pump heat-dissipating situation.For general hydraulic system.When its work, the variation range of fluid temperature rise is less, and therefore its ram pump leakage rate is constant.But for deficient liquid coolant pressing system, when its work, the variation range of fluid can reach up to a hundred degrees Celsius, and therefore ram pump leakage rate can have greatly changed, and can not simply think a constant.

The problems referred to above make existing heat analysis method not be suitable for ram pump in deficient liquid coolant pressing system.

Summary of the invention

The present invention is directed to the problem that existing heat analysis method is not suitable for ram pump in deficient liquid coolant pressing system, propose a kind of heat analysis method for deficient liquid coolant pressing system ram pump.

For a heat analysis method for deficient liquid coolant pressing system ram pump, comprise the following steps:

Step one, utilize lumped parameter method, set up the five temperature node thermal models owing liquid coolant pressing system ram pump.

Deficient liquid coolant pressing system ram pump five temperature node thermal model described in step one, is specifically divided into oil suction temperature node, oil outlet temperature node, leaks temperature node, case temperature node and inversion temperature node by ram pump.

Step 2, owe the thermal model of liquid coolant pressing system ram pump according in step one, set up the thermal balance equation of five temperature nodes.

The thermal balance equation of five temperature nodes described in step 2, specifically refers to:

Oil suction temperature node thermal balance equation:

$\begin{array}{c}\frac{{\mathrm{dT}}_t}{\mathrm{dt}}=\frac{1}{c_p{m}_t}[\mathrm{\ρ}(Q_{\mathrm{in}}-Q_{\mathrm{il}})(c_p(T_c-T_t)+(1-{\mathrm{\α}}_P\frac{(T_c+T_t)}{2})V_T(P_C-P_T))+\mathrm{\ρ}{Q}_{\mathrm{il}}(c_p(T_p-T_t)+(1-{\mathrm{\α}}_P\frac{(T_p-T_t)}{2})V_T(P_P-P_T))\\ +\mathrm{\ρ}(Q_{\mathrm{in}}-Q_{\mathrm{il}})c_p(T_c-T_t)+T_c{\mathrm{\α}}_P{V}_c\frac{{\mathrm{dP}}_C}{\mathrm{dt}}+T_t{\mathrm{\α}}_P{V}_T\frac{{\mathrm{dP}}_T}{\mathrm{dt}}]\end{array}$

Oil outlet temperature node thermal balance equation:

$\frac{{\mathrm{dT}}_p}{\mathrm{dt}}=\frac{1}{c_p{m}_P}[\mathrm{\ρ}(Q_{\mathrm{in}}-Q_{\mathrm{el}})(c_P(T_t-T_p)+(1-{\mathrm{\α}}_P\frac{(T_p+T_t)}{2})V_P(P_T-P_P))+Q_{\mathrm{in}}(P_P-P_T)+L_n+L_d+T_P{\mathrm{\α}}_P{V}_P\frac{{\mathrm{dP}}_p}{\mathrm{dt}}]$

Leak temperature node thermal balance equation:

$\frac{{\mathrm{dT}}_l}{\mathrm{dt}}=\frac{1}{c_P{m}_l}[\mathrm{\ρ}{Q}_{\mathrm{el}}(c_p(T_P-T_l)+(1-{\mathrm{\α}}_p\frac{(T_P+T_l)}{2})V_l(P_P-P_l))-k_{\mathrm{fw}}{A}_{\mathrm{fw}}(T_l-T_w)+T_l{\mathrm{\α}}_P{V}_l\frac{{\mathrm{dP}}_l}{\mathrm{dt}}]$

Case temperature node thermal balance equation:

$\frac{{\mathrm{dT}}_w}{\mathrm{dt}}=\frac{1}{c_w{m}_w}[k_{\mathrm{fw}}{A}_{\mathrm{fw}}(T_l-T_w)-k_{\mathrm{wa}}{A}_{\mathrm{wa}}(T_w-T_a)+L_c]$

Inversion temperature node thermal balance equation:

$\begin{array}{c}\frac{{\mathrm{dT}}_c}{\mathrm{dt}}=\frac{1}{c_P{m}_c}[\mathrm{\ρ}(Q_{\mathrm{in}}-Q_{\mathrm{el}}-Q_{\mathrm{il}})(c_p(T_p-T_c)+(1-{\mathrm{\α}}_P\frac{(T_p+T_c)}{2})V_c(P_p-P_c))+\mathrm{\ρ}{Q}_{\mathrm{el}}(c_p(T_l-T_c)\\ +(1-{\mathrm{\α}}_P\frac{(T_l+T_c)}{2})V_c(P_l-P_c))-k_{\mathrm{wa}}{A}_c(T_c-T_a)+T_p{\mathrm{\α}}_P{V}_P\frac{{\mathrm{dP}}_P}{\mathrm{dt}}+T_l{\mathrm{\α}}_P{V}_l\frac{{\mathrm{dP}}_l}{\mathrm{dt}}]\end{array}$

Step 3, set up the accurate leakage rate model of ram pump, and carry it in each temperature node thermal balance equation that step 2 sets up.

The accurate leakage rate model of ram pump described in step 3, specifically refers to:

Average leaked amount Q between plunger and cylinder holes _pb:

$Q_{\mathrm{pb}}=\frac{{\mathrm{\πd}}_p{\mathrm{\δ}}_{\mathrm{pb}}^3(P_p-P_l)}{12\mathrm{\μ}}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\frac{1}{l_{\mathrm{pb}}}+\frac{{\mathrm{\πd}}_p{\mathrm{\δ}}_{\mathrm{pb}}}{2}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{v}_{\mathrm{pb}}$

Piston shoes are with the leakage rate Q in gap between swash plate _ss:

$Q_{\mathrm{ss}}=\mathrm{\π}{\mathrm{\δ}}_{\mathrm{ss}}^3\frac{P_p-P_l}{6\mathrm{\μ}\ln \left(\frac{R_{s0}}{R_{s1}}\right)}$

The leakage rate Q of valve plate oil extraction district's oil sealing band actual cornerite scope inner fluid _vb:

The each temperature node thermal balance equation accurate leakage rate model being brought into step 2 foundation described in step 3, specifically refers to:

Ram pump internal leakage flow Q _il:

Q _il＝Q _vb1

Ram pump external leakage flow Q _el:

Q _el＝Q _vb2+Q _pb+Q _ss

Step 4, calculate the dynamic viscosity parameter of fluid of owing to circulate in liquid coolant pressing system, and is substituted in the accurate leakage rate of ram pump in step 3, obtain the dynamic accurate leakage rate relevant to oil liquid temperature.

Calculating described in step 4 is owed to circulate in liquid coolant pressing system the dynamic viscosity parameter of fluid, specifically refers to: according to the viscosity-temperature characteristics curve using fluid in deficient liquid coolant pressing system, calculates Vogel and glues constant in warm approximate formula.Vogel glues warm approximate formula:

$\mathrm{\μ}\left(T\right)=a\·e^{\left(\frac{b}{T+c}\right)}$

Calculating Vogel glues the constant in warm approximate formula, namely refers to the concrete numerical value calculating a, b, c in above formula.

The dynamic viscosity parameter of the fluid that circulates in deficient liquid coolant pressing system being substituted in the accurate leakage rate of ram pump in step 3 described in step 4, obtains the dynamically accurate leakage rate relevant to oil liquid temperature and specifically refers to: will determine that the Vogel after constant glues warm formula and substitutes into average leaked amount Q between the plunger of step 3 and cylinder holes _pb, piston shoes are with the leakage rate Q in gap between swash plate _ss, the leakage rate Q of valve plate oil extraction district's oil sealing band actual cornerite scope inner fluid _vbin, dynamically accurately leakage rate is as follows to obtain three:

Average leaked amount Q between dynamic plunger and cylinder holes _pb(T):

$Q_{\mathrm{pb}}\left(T\right)=\frac{{\mathrm{\πd}}_p{\mathrm{\δ}}_{\mathrm{pb}}^3(P_p-P_l)}{12(a\·e^{\left(\frac{b}{T+c}\right)})}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\frac{1}{l_{\mathrm{pb}}}+\frac{{\mathrm{\πd}}_p{\mathrm{\δ}}_{\mathrm{pb}}}{2}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{v}_{\mathrm{pb}}$

Dynamic piston shoes are with the leakage rate Q in gap between swash plate _ss(T):

$Q_{\mathrm{ss}}\left(T\right)={\mathrm{\π\δ}}_{\mathrm{ss}}^3\frac{P_p-P_l}{6(a\·e^{\left(\frac{b}{T+c}\right)})\ln \left(\frac{R_{s0}}{R_{s1}}\right)}$

The leakage rate Q of dynamic valve plate oil extraction district's oil sealing band actual cornerite scope inner fluid _vb(T):

Step 5, the dynamically accurately leakage rate in step 4 substituted in the thermal balance equation in step 2, these equations of simultaneous solution, draw the temperature of each temperature node.

Advantage of the present invention and good effect are: a kind of heat analysis method for ram pump in deficient liquid coolant pressing system provided by the present invention, by introducing inversion temperature node, to solve in general hydraulic system ram pump heat analysis method and to reckon without that deficient liquid coolant pressing system oil circuit is short, the problem of the little feature of area of dissipation; Method provided by the present invention introduces the accurate leakage rate of ram pump simultaneously, and the dynamic viscosity of fluid is substituted in accurate leakage rate, obtain dynamically accurate leakage rate, solve when using general hydraulic system ram pump heat analysis method process to owe liquid coolant pressing system ram pump thermal analyses problem, due to ignore oil viscosity by temperature rise affect reduce so that leakage rate is changed, cause the problem that result of calculation deviation is larger.

Accompanying drawing explanation

Fig. 1 of the present inventionly determines a kind of heat analysis method overall flow figure for plunger pumping method in deficient liquid coolant pressing system;

Fig. 2 is the ram pump schematic diagram in typical Normal hydraulic system and deficient liquid coolant pressing system;

Fig. 3 is for the thermoanalytical four temperature node thermal model schematic diagram of Normal hydraulic system ram pump;

Fig. 4 is the deficient liquid coolant pressing system ram pump five temperature node thermal model schematic diagram proposed in step one of the present invention;

Fig. 5 is the internal and outernal leakage flow three part composition schematic diagram of ram pump;

Fig. 6 is the viscosity-temperature curve of No. 12 aircraft fluids;

Fig. 7 uses the plunger pump shell temperature junction temperature that calculates of heat analysis method provided by the invention with the contrast of embodiment observed temperature;

Fig. 8 uses the result calculated for deficient liquid coolant pressing system ram pump heat analysis method provided by the invention with the error between embodiment measured result;

Embodiment

Below in conjunction with accompanying drawing and example, the present invention is described in further detail.

Step one, utilize lumped parameter method, set up the five temperature node thermal models owing liquid coolant pressing system ram pump.

The attached ram pump that Figure 2 shows that in typical Normal hydraulic system and deficient liquid coolant pressing system, the ram pump wherein in 1-Normal hydraulic system, 2-owes the ram pump in liquid coolant pressing system.Can find out the running environment relative to ram pump in Normal hydraulic system from accompanying drawing 2, the ram pump recycle oil in deficient liquid coolant pressing system is short out, area of dissipation is little.

The current thermal analyses for ram pump in hydraulic system, adopts lumped parameter method more.When utilizing this kind of heat analysis method to carry out thermal analyses to ram pump, first ram pump is divided into four temperature nodes, respectively: ram pump oil suction temperature node, ram pump oil outlet temperature node, ram pump leak temperature node, plunger pump shell temperature node; Set up the thermal model of ram pump four node afterwards; Thermal balance equation corresponding to each temperature node is write finally by first law of thermodynamics row, the temperature rise of each temperature node of ram pump is obtained by simultaneous solution thermal balance equation group, and then thermal analyses (reference paper 1:LICheng-gong is carried out to ram pump, et al., " Thermal-hydraulic Modeling and Simulation of PistonPump, " Chinese Journal of Aeronautics, Vol.19 No.4, pp.354-358,2006).1. the four temperature node thermal models that said method is set up as shown in Figure 3, are wherein oil suction temperature node, T _tfor the temperature of oil suction temperature node, be 2. oil outlet temperature node, T _pfor the temperature of oil outlet temperature node, 3. for leaking temperature node, T _lfor leaking the temperature of temperature node, be 4. case temperature node, T _wfor the temperature of case temperature node; T _afor ambient temperature; Q _tfor the inhalation flow of ram pump, Q _pfor the delivery flow of ram pump, Q _ilfor the internal leakage of ram pump, Q _elfor the leakage quantity that leaks of ram pump; l _dfor hydrodynamic force loss, l _nfor viscous friction loss, l _udry friction loss when ram pump runs.Node 1., 2., 3. between solid arrow represent and carry out by hydraulic oil liquid the heat that transmits, arrow points represents the direction that heat transmits; Node dotted arrow 3. and 4. represents the heat trnasfer carried out with convection current and conduction pattern.

In the above-mentioned methods, ram pump is divided into four temperature nodes, such division is only applicable to the situation of ram pump in Normal hydraulic system.And this kind of method thinks that the oil liquid temperature that ram pump sucks is constant value, this is because in common hydraulic system, between ram pump oil suction and oil extraction, there is very long oil circuit, and through fuel tank, so just have enough area of dissipations for its heat radiation, therefore can think that the oil liquid temperature that ram pump sucks is constant value.But for deficient liquid coolant pressing system, between ram pump oil suction and oil extraction, oil circuit is very short, and do not have fuel tank to provide enough area of dissipations to dispel the heat for it, so suction oil liquid temperature can not be considered as constant value by it as ram pump in Normal hydraulic system, so said method be not suitable for the thermal analyses of ram pump in deficient liquid coolant pressing system.

In view of the deficiency of above-mentioned heat analysis method, the present invention utilizes lumped parameter method, proposes a kind of for owing the thermoanalytical five temperature node division methods of liquid coolant pressing system ram pump, and sets up the thermal model owing ram pump in liquid coolant pressing system on this basis.Owe liquid coolant pressing system ram pump five temperature node thermal model as shown in Figure 4, relative to the thermal model of four temperature nodes, the deficient liquid coolant pressing system ram pump five temperature node thermal model shown in accompanying drawing 4 adds 5. inversion temperature node, T _cfor the temperature of inversion temperature node.This temperature node is for describing from the heat transfer process between the oil extraction to oil suction of deficient liquid coolant pressing system ram pump.

Step 2, owe the thermal model of liquid coolant pressing system ram pump according in step one, set up the thermal balance equation of five temperature nodes.

The method setting up temperature node thermal balance equation is as follows:

Each temperature node can write out energy conservation relation according to first law of thermodynamics row, is shown below:

$\stackrel{\·}{Q}-{\stackrel{\·}{W}}_{\mathrm{net}}=\mathrm{\Σ}{\stackrel{\·}{m}}_{\mathrm{out}}{h}_{\mathrm{out}}-\mathrm{\Σ}{\stackrel{\·}{m}}_{\mathrm{in}}{h}_{\mathrm{in}}+\stackrel{\·}{E}---\left(1\right)$

(1) in formula, for temperature node is with the rate of heat exchange between external environment condition, do by temperature node the rate of change of net work, for comprising the rate of change of energy in temperature node, with be respectively the oil quality rate of change flowed into flowing out this temperature node, h _inand h _outbe respectively the specific entropy flowed into flowing out this temperature node oil quality.

If the temperature of temperature node is T, the thermal balance equation of the temperature T t change in time of temperature node can be drawn with certificate (1) formula, be shown below:

$\frac{\mathrm{dT}}{\mathrm{dt}}=\frac{1}{c_{p}m}[\mathrm{\Σ}{\stackrel{\·}{m}}_{\mathrm{in}}(c_p(T_{\mathrm{in}}-T)+(1-{\mathrm{\α}}_{p}T)V(p_{\mathrm{in}}-p))-\stackrel{\·}{Q}-{\stackrel{\·}{W}}_{\mathrm{net}}+\mathrm{mT}{\mathrm{\α}}_{p}V\frac{\mathrm{dp}}{\mathrm{dt}}]---\left(\text{2}\right)$

(2) in formula, c _pfor the hydraulic oil specific heat of temperature node, m is the oil quality of temperature node, T _infor flowing into the temperature of temperature node fluid, α _pfor the volume expansivity of temperature node, V is the specific volume of temperature node, p _infor flowing into the pressure of temperature node fluid, p is the pressure of the original fluid of temperature node.

The heat balance equation of each temperature node in liquid coolant pressing system ram pump five node thermodynamical model can be owed as follows shown in the formula of (3) ~ (7) according to formula (2):

The heat balance equation of ram pump oil suction temperature node is shown below:

$\begin{array}{c}\frac{{\mathrm{dT}}_t}{\mathrm{dt}}=\frac{1}{c_p{m}_t}[\mathrm{\ρ}(Q_{\mathrm{in}}-Q_{\mathrm{il}})(c_p(T_c-T_t)+(1-{\mathrm{\α}}_P\frac{(T_c+T_t)}{2})V_T(P_C-P_T))+\mathrm{\ρ}{Q}_{\mathrm{il}}(c_p(T_p-T_t)+(1-{\mathrm{\α}}_P\frac{(T_p-T_t)}{2})V_T(P_P-P_T))\\ +\mathrm{\ρ}(Q_{\mathrm{in}}-Q_{\mathrm{il}})c_p(T_c-T_t)+T_c{\mathrm{\α}}_P{V}_c\frac{{\mathrm{dP}}_C}{\mathrm{dt}}+T_t{\mathrm{\α}}_P{V}_T\frac{{\mathrm{dP}}_T}{\mathrm{dt}}]\end{array}---\left(3\right)$

The heat balance equation of ram pump oil outlet temperature node is shown below:

$\frac{{\mathrm{dT}}_p}{\mathrm{dt}}=\frac{1}{c_p{m}_P}[\mathrm{\ρ}(Q_{\mathrm{in}}-Q_{\mathrm{el}})(c_P(T_t-T_p)+(1-{\mathrm{\α}}_P\frac{(T_p+T_t)}{2})V_P(P_T-P_P))+Q_{\mathrm{in}}(P_P-P_T)+L_n+L_d+T_P{\mathrm{\α}}_P{V}_P\frac{{\mathrm{dP}}_p}{\mathrm{dt}}]---\left(4\right)$

The heat balance equation of ram pump Leakage Energy liquid temp node is shown below:

$\frac{{\mathrm{dT}}_l}{\mathrm{dt}}=\frac{1}{c_P{m}_l}[\mathrm{\ρ}{Q}_{\mathrm{el}}(c_p(T_P-T_l)+(1-{\mathrm{\α}}_p\frac{(T_P+T_l)}{2})V_l(P_P-P_l))-k_{\mathrm{fw}}{A}_{\mathrm{fw}}(T_l-T_w)+T_l{\mathrm{\α}}_P{V}_l\frac{{\mathrm{dP}}_l}{\mathrm{dt}}]---\left(5\right)$

The heat balance equation of plunger pump shell temperature node is shown below:

$\frac{{\mathrm{dT}}_w}{\mathrm{dt}}=\frac{1}{c_w{m}_w}[k_{\mathrm{fw}}{A}_{\mathrm{fw}}(T_l-T_w)-k_{\mathrm{wa}}{A}_{\mathrm{wa}}(T_w-T_a)+L_c]---\left(6\right)$

The heat balance equation of ram pump inversion temperature node is shown below:

$\begin{array}{c}\frac{{\mathrm{dT}}_c}{\mathrm{dt}}=\frac{1}{c_P{m}_c}[\mathrm{\ρ}(Q_{\mathrm{in}}-Q_{\mathrm{el}}-Q_{\mathrm{il}})(c_p(T_p-T_c)+(1-{\mathrm{\α}}_P\frac{(T_p+T_c)}{2})V_c(P_p-P_c))+\mathrm{\ρ}{Q}_{\mathrm{el}}(c_p(T_l-T_c)\\ +(1-{\mathrm{\α}}_P\frac{(T_l+T_c)}{2})V_c(P_l-P_c))-k_{\mathrm{wa}}{A}_c(T_c-T_a)+T_p{\mathrm{\α}}_P{V}_P\frac{{\mathrm{dP}}_P}{\mathrm{dt}}+T_l{\mathrm{\α}}_P{V}_l\frac{{\mathrm{dP}}_l}{\mathrm{dt}}]\end{array}---\left(7\right)$

Wherein: c _p, c _wbe respectively the specific heat of hydraulic oil and plunger pump shell, m _t, m _p, m _l, m _w, m _cbe respectively the oil quality of oil suction temperature node, oil outlet temperature node, leakage temperature node, case temperature node, inversion temperature node, T _t, T _p, T _l, T _w, T _cbe respectively the temperature of oil suction temperature node, oil outlet temperature node, leakage temperature node, case temperature node, inversion temperature node; ρ is hydraulic oil liquid density, and D is ram pump discharge capacity, and ω is ram pump rotating speed, k _fw, k _wabe respectively the same housing of hydraulic oil liquid, housing with the heat transfer coefficient between external environment, A _fwfor hydraulic oil liquid is with contact area heat conducting between housing, A _wafor housing is with contact area heat conducting between external environment, A _cfor hydraulic oil liquid is from oil-discharging cavity to the area of dissipation oil sucting cavity process, L _n, L _d, L _ube respectively the viscous friction loss of ram pump, hydrodynamic force loss and dry friction loss, T _infor fuel tank oil liquid temperature, P _p, P _t, P _c, P _lbe respectively the oil suction pressure of ram pump, oil extraction pressure, transfer pressure, return pressure, V _p, V _t, V _c, V _lbe respectively the fluid specific volume of ram pump oil suction temperature node, oil outlet temperature node, inversion temperature node, leakage temperature node.

Step 3, set up the accurate leakage rate model of ram pump, and carry it in each temperature node thermal balance equation that step 2 sets up.

In the deficient liquid coolant pressing system ram pump five node heat balance equation set up in step 2 (3) ~ (7) formula, comprise the total flow Q of ram pump _in, external leakage flow Q _eland internal leakage flow Q _il.Set up the accurate leakage rate model owing liquid coolant pressing system ram pump in step 3 namely to refer to set up ram pump total flow Q _in, external leakage flow Q _eland internal leakage flow Q _ilaccurate model.

The total flow Q of ram pump _inaccurate model be shown below (list of references 2: Wang Zhanlin, " hydraulic servocontrol ", publishing house of Beijing Aeronaution College (existing BJ University of Aeronautics & Astronautics publishing house), 1987):

$Q_{\mathrm{in}}=z\frac{{{\mathrm{\πd}}_p}^2}{4}n{D}_f\mathrm{tg\γ}---\left(8\right)$

(8), in formula, z is the number of plungers of ram pump, d _pfor diameter of plunger, n is the motor speed of actuation plunger pump, D _ffor plunger pitch circle diameter, γ is the swashplate angle of ram pump.

External leakage flow Q _eland internal leakage flow Q _ilfor the leakage flow of ram pump.As shown in Figure 5, the internal and outernal leakage flow of ram pump is made up of three parts: Part I is the leakage rate Q in the fluid gap through between plunger 3 and cylinder holes 4 in plunger cavity _pb; Part II is the leakage flow Q of the actual cornerite scope inner fluid of valve plate oil extraction district's oil sealing band 5 _vb; Part III is the leakage flow Q in fluid gap through between piston shoes 6 and swash plate 7 _ss.Q _pb, Q _vb, Q _sscalculating can with reference to list of references 2.

The leakage rate in fluid gap through between plunger and cylinder holes can be calculated as follows:

$Q_{\mathrm{pb}}=\frac{{\mathrm{\πd}}_p{\mathrm{\δ}}_{\mathrm{pb}}^3(P_p-P_l)}{12\mathrm{\μ}}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\frac{1}{l_{\mathrm{pbi}}}+\frac{{\mathrm{\πd}}_p{\mathrm{\δ}}_{\mathrm{pb}}}{2}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{v}_{\mathrm{pbi}}---\left(9\right)$

(9) in formula, δ _pbfor the gap size between plunger and cylinder holes, μ is the kinetic viscosity of fluid, l _pbibe i-th total length between plunger and cylinder holes, v _pbibe the movement velocity of i-th plunger, M is the number of plungers entering oil extraction district, P _pfor the oil suction pressure of ram pump, P _lfor the return pressure of ram pump.

The leakage flow Q of oil distribution casing oil extraction district's oil sealing band actual cornerite scope inner fluid _vbcan be calculated as follows:

(10) in formula, Q _vb1for interior oil sealing band leakage flow, Q _vb2for outer oil sealing band leakage flow, for the actual cornerite of valve plate oil extraction district's oil sealing band, δ _vbfor gap size between valve plate and cylinder body, R _v1and R _v2for oil sealing band internal diameter and external diameter in valve plate, R _v3and R _v4for the outer oil sealing band internal diameter of valve plate and external diameter.

The leakage flow Q in gap between piston shoes and swash plate _sscan be calculated as follows:

$Q_{\mathrm{ss}}=\mathrm{\π}{\mathrm{\δ}}_{\mathrm{ss}}^3\frac{P_p-P_l}{6\mathrm{\μ}\ln \left(\frac{R_{s0}}{R_{s1}}\right)}---\left(11\right)$

(11) in formula, δ _ssfor the gap size between piston shoes and swash plate, R _s1for piston shoes oil sump radius, R _s0for the maximum exradius of piston shoes.

The internal leakage flow Q of ram pump _illeak primarily of oil sealing band in valve plate and caused, the therefore internal leakage flow Q of ram pump _ilcan be calculated as follows:

Q _il＝Q _vb1(12)

Except internal leakage, other forms of leakage part enters the oil return circuit of two-way quantitative ram pump with the form of external leakage, so external leakage flow Q _elcan be calculated as follows:

Q _el＝Q _vb2+Q _pb+Q _ss(13)

(8), (12), (13) formula are substituted in (3) ~ (7), namely obtains the deficient liquid coolant pressing system ram pump heat balance equation comprising accurate leakage rate model.

Step 4, calculate the dynamic viscosity parameter of fluid of owing to circulate in liquid coolant pressing system, and is substituted in the accurate leakage rate of ram pump in step 3, obtain the dynamic accurate leakage rate relevant to oil liquid temperature.

The concrete steps calculating in deficient liquid coolant pressing system the dynamic viscosity parameter of the fluid that circulates are as follows:

The first step: select correctly to describe deficient liquid coolant pressing system use the sticky temperature formula of hydraulic oil liquid viscosity and temperature relation.In many formula, Vogel glues warm approximate formula and is considered to be suitable for engineering calculation most.(list of references 3:J.Koralewski, " Influence of hydraulic oil viscosity on the volumetric losses in avariable capacity piston pump; " Polish Maritime Research, 18 (3): 55-65,2011).Vogel glues warm approximate formula such as formula shown in (14):

$\mathrm{\μ}\left(T\right)=a\·e^{\left(\frac{b}{T+c}\right)}---\left(14\right)$

In formula: T is the temperature of hydraulic oil liquid, the viscosity that μ (T) is hydraulic oil liquid during temperature T, a, b, c are constant.

Second step: according in deficient liquid coolant pressing system use the viscosity-temperature curve of hydraulic oil liquid, calculate the concrete numerical value that Vogel glues constant a, b, c in warm formula.

Each hydraulic oil liquid all can have corresponding viscosity-temperature curve, takes up an official post and gets 3 points, namely select three groups of synthermal relations of viscosity, carry it in formula (14), can solve the concrete numerical value determining constant a, b, c at its viscosity-temperature curve.

To determine that the Vogel after constant value glues warm formula and substitutes into average leaked amount Q between the plunger of step 3 and cylinder holes _pb, piston shoes are with the leakage rate Q in gap between swash plate _ss, the leakage rate Q of valve plate oil extraction district's oil sealing band actual cornerite scope inner fluid _vbin, dynamically accurately leakage rate is as follows to obtain three:

Average leaked amount Q between dynamic plunger and cylinder holes _pb(T):

$Q_{\mathrm{pb}}\left(T\right)=\frac{{\mathrm{\πd}}_p{\mathrm{\δ}}_{\mathrm{pb}}^3(P_p-P_l)}{12(a\·e^{\left(\frac{b}{T+c}\right)})}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\frac{1}{l_{\mathrm{pb}}}+\frac{{\mathrm{\πd}}_p{\mathrm{\δ}}_{\mathrm{pb}}}{2}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{v}_{\mathrm{pb}}---\left(15\right)$

Dynamic piston shoes are with the leakage rate Q in gap between swash plate _ss(T):

$Q_{\mathrm{ss}}\left(T\right)={\mathrm{\π\δ}}_{\mathrm{ss}}^3\frac{P_p-P_l}{6(a\·e^{\left(\frac{b}{T+c}\right)})\ln \left(\frac{R_{s0}}{R_{s1}}\right)}---\left(16\right)$

The leakage rate Q of dynamic valve plate oil extraction district's oil sealing band actual cornerite scope inner fluid _vb(T):

Step 5, the dynamically accurately leakage rate in step 4 substituted in the thermal balance equation in step 2, these equations of simultaneous solution, draw the temperature of each temperature node.

Formula (15) ~ (17) in step 4 are substituted in formula (12) and formula (13), again formula (12) and formula (13) are substituted in formula (3) ~ (7), simultaneous solution formula (3) ~ (7), solve the numerical value of each temperature node, namely can be used for the thermal analyses of ram pump in deficient liquid coolant pressing system.

embodiment

The ram pump example that uses of liquid coolant pressing system is owed for object below with one, heat analysis method provided by the present invention is used to carry out thermal analyses to it, use be the invention provides method acquired results to compare with actual experiment acquisition result, use heat analysis method provided by the invention to obtain the correctness of result in order to checking, and then prove practicality and the validity of heat analysis method provided by the invention.Each parameter value as the deficient liquid coolant pressing system ram pump of embodiment is as shown in table 1.

Table 1 is for thermoanalytical deficient liquid coolant pressing system ram pump parameter

According to the deficient liquid coolant pressing system ram pump five temperature node thermal model that step one provides, set up the thermal model of this embodiment.

According to step 2, the thermal balance equation of constitution and implementation example five temperature nodes.

According to step 3, the parameter in table 1 is substituted into formula (8) ~ (13), calculates the accurate leakage rate of this embodiment.

According to step 4, calculate in deficient liquid coolant pressing system the dynamic viscosity parameter of the fluid that circulates, the hydraulic oil liquid used in this embodiment is No. 12 aircraft fluids.The attached viscosity-temperature curve that Figure 6 shows that No. 12 aircraft fluids, curve shown in accompanying drawing 6 is chosen 3 points:

T ₁＝0℃,μ ₁＝18m ²/s

T ₂＝20℃,μ ₂＝15.62m ²/s

T ₃＝80℃,μ ₃＝10.65m ²/s

Substitute into above-mentioned 3 in formula (14), simultaneous solution can show that the occurrence that No. 12 aircraft fluid Vogel glue constant a, b, c in warm formula is as follows:

a＝91.3755,b＝3563.2786,c＝698.3607

Then can show that the Vogel of No. 12 aircraft fluids glues warm formula and is:

$\mathrm{\μ}\left(T\right)=91.3755\·e^{\left(\frac{3563.2786}{T+698.3607}\right)}---\left(18\right)$

Formula (18) is substituted in formula (15) ~ (17), the exact flow rate of the dynamic viscosity parameter with the fluid that circulates in deficient liquid coolant pressing system can be tried to achieve.

According to step 5, the dynamically accurate leakage rate in step 4 substituted in the thermal balance equation in step 2, these equations of simultaneous solution, draw each temperature junction temperature curve over time.

In the present embodiment, owe liquid coolant pressing system to run with following working method: the pressure that system is initial, namely load pressure is 21mPa, after 190s, becoming 17mPa, becomes 14mPa at 205s place, finally becomes 10mPa at 220s place.Temperature sensor in embodiment is installed on the housing place of deficient liquid coolant pressing system ram pump, and measured value is the temperature of plunger pump shell temperature node.The plunger pump shell temperature junction temperature using heat analysis method provided by the invention to calculate with embodiment observed temperature contrast as shown in Figure 7.

As can be seen from accompanying drawing 7, the temperature rise of plunger pump shell is in stable when 190s, afterwards due to the decline of system pressure, plunger pump shell temperature rise also declines thereupon, uses between the actual measured results of the temperature variation curve calculated for the heat analysis method of deficient liquid coolant pressing system ram pump provided by the invention with embodiment and has identical trend.Use the result calculated for deficient liquid coolant pressing system ram pump heat analysis method provided by the invention with the error between embodiment measured result as shown in Figure 8.As can be seen from such as Fig. 8, the error between above-mentioned two results is between 10% ~-5%, and two kinds of results have the good goodness of fit.Therefore prove that a kind of heat analysis method for deficient liquid coolant pressing system ram pump provided by the present invention has practicality and validity.

Claims (1)

1., for a heat analysis method for ram pump in deficient liquid coolant pressing system, it is characterized in that comprising the following steps,

Step one, utilize lumped parameter method, set up the five temperature node thermal models owing liquid coolant pressing system ram pump; Specifically ram pump is divided into oil suction temperature node, oil outlet temperature node, leaks temperature node, case temperature node and inversion temperature node;

Step 2, owe the thermal model of liquid coolant pressing system ram pump according in step one, set up the thermal balance equation of five temperature nodes;

The thermal balance equation of described five temperature nodes, specifically refers to:

Oil suction temperature node thermal balance equation:

$\begin{array}{c}\frac{{\mathrm{dT}}_1}{\mathrm{dt}}=\frac{1}{c_p{m}_t}[\mathrm{\ρ}(Q_{\mathrm{in}}-Q_{\mathrm{il}})(c_p(T_c-T_t)+(1-{\mathrm{\α}}_P\frac{(T_c+T_t)}{2})V_T(P_C-P_T))+{\mathrm{\ρQ}}_{\mathrm{il}}(c_p(T_p-T_t)+(1-{\mathrm{\α}}_P\frac{(T_p+T_t)}{2})V_T(P_P-P_T))\\ +\mathrm{\ρ}(Q_{\mathrm{in}}-Q_{\mathrm{il}})c_p(T_c-T_t)+T_c{\mathrm{\α}}_P{V}_c\frac{{\mathrm{dP}}_C}{\mathrm{dt}}+T_t{\mathrm{\α}}_P{V}_T\frac{{\mathrm{dP}}_T}{\mathrm{dt}}]\end{array}$

Oil outlet temperature node thermal balance equation:

$\frac{{\mathrm{dT}}_p}{\mathrm{dt}}=\frac{1}{c_p{m}_P}[\mathrm{\ρ}(Q_{\mathrm{in}}-Q_{\mathrm{el}})(c_P(T_t-T_p)+(1-{\mathrm{\α}}_P\frac{(T_p+T_t)}{2})V_P(P_T-P_P))+Q_{\mathrm{in}}(P_P-P_T)+L_n+L_d+T_P{\mathrm{\α}}_P{V}_P\frac{{\mathrm{dP}}_p}{\mathrm{dt}}]$

Leak temperature node thermal balance equation:

$\frac{{\mathrm{dT}}_l}{\mathrm{dt}}=\frac{1}{c_P{m}_l}[{\mathrm{\ρQ}}_{\mathrm{el}}(c_P(T_P-T_l)+(1-{\mathrm{\α}}_p\frac{(T_P+T_l)}{2})V_l(P_P-P_l))-k_{\mathrm{fw}}{A}_{\mathrm{fw}}(T_l-T_w)+T_l{\mathrm{\α}}_P{V}_l\frac{{\mathrm{dP}}_l}{\mathrm{dt}}]$

Case temperature node thermal balance equation:

$\frac{{\mathrm{dT}}_w}{\mathrm{dt}}=\frac{1}{c_w{m}_w}[k_{\mathrm{fw}}{A}_{\mathrm{fw}}(T_l-T_w)-k_{\mathrm{wa}}{A}_{\mathrm{wa}}(T_w-T_a)+L_c]$

Inversion temperature node thermal balance equation:

$\begin{array}{c}\frac{{\mathrm{dT}}_c}{\mathrm{dt}}=\frac{1}{c_p{m}_t}[\mathrm{\ρ}(Q_{\mathrm{in}}-Q_{\mathrm{el}}{-Q}_{\mathrm{il}})(c_p(T_p-T_c)+(1-{\mathrm{\α}}_P\frac{(T_c+T_t)}{2})V_c(P_p-P_c))+{\mathrm{\ρQ}}_{\mathrm{el}}(c_p(T_l-T_c)\\ +(1-{\mathrm{\α}}_P\frac{(T_l-T_c)}{2})V_c\mathrm{\ρ}(P_l-P_c))k_{\mathrm{wa}}{A}_c(T_c-T_a)+T_p{\mathrm{\α}}_P{V}_P\frac{{\mathrm{dP}}_P}{\mathrm{dt}}+T_l{\mathrm{\α}}_P{V}_l\frac{{\mathrm{dP}}_T}{\mathrm{dt}}]\end{array}$

Step 3, set up the accurate leakage rate model of ram pump, and carry it in each temperature node thermal balance equation that step 2 sets up;

The accurate leakage rate model of described ram pump, specifically refers to:

Average leaked amount Q between plunger and cylinder holes _pb:

$Q_{\mathrm{pb}}=\frac{\mathrm{\π}{d}_p{\mathrm{\δ}}_{\mathrm{pb}}^3(P_p-P_l)}{12\mathrm{\μ}}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\frac{1}{l_{\mathrm{pb}}}+\frac{{\mathrm{\πd}}_p{\mathrm{\δ}}_{\mathrm{pb}}}{2}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{v}_{\mathrm{pb}}$

Piston shoes are with the leakage rate Q in gap between swash plate _ss:

$Q_{\mathrm{ss}}={\mathrm{\π\δ}}_{\mathrm{ss}}^3\frac{P_p-P_l}{6\mathrm{\μ}\ln \left(\frac{R_{s0}}{R_{s1}}\right)}$

The leakage rate Q of valve plate oil extraction district's oil sealing band actual cornerite scope inner fluid _vb:

The described each temperature node thermal balance equation accurate leakage rate model being brought into step 2 foundation, specifically refers to:

Ram pump internal leakage flow Q _il:

Q _il＝Q _vb1

Ram pump external leakage flow Q _el:

Q _el＝Q _vb2+Q _pb+Q _ss

Step 4, calculate the dynamic viscosity parameter of fluid of owing to circulate in liquid coolant pressing system, and is substituted in the accurate leakage rate of ram pump in step 3, obtain the dynamic accurate leakage rate relevant to oil liquid temperature;

Described calculating is owed to circulate in liquid coolant pressing system the dynamic viscosity parameter of fluid, specifically refers to: according to the viscosity-temperature characteristics curve using fluid in deficient liquid coolant pressing system, calculates Vogel and glues constant in warm approximate formula; To determine that the Vogel after constant glues warm formula and substitutes into average leaked amount Q between the plunger of step 3 and cylinder holes _pb, piston shoes are with the leakage rate Q in gap between swash plate _ss, the leakage rate Q of valve plate oil extraction district's oil sealing band actual cornerite scope inner fluid _vbin, dynamically accurately leakage rate is as follows to obtain three:

Average leaked amount Q between dynamic plunger and cylinder holes _pb(T):

$Q_{\mathrm{pb}}\left(T\right)=\frac{{\mathrm{\πd}}_p{\mathrm{\δ}}_{\mathrm{pb}}^3(P_p-P_l)}{12(a\·e^{\left(\frac{b}{T+c}\right)})}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}\frac{1}{l_{\mathrm{pb}}}+\frac{{\mathrm{\πd}}_p{\mathrm{\δ}}_{\mathrm{pb}}}{2}\underset{i=1}{\overset{M}{\mathrm{\Σ}}}{v}_{\mathrm{pb}}$

Dynamic piston shoes are with the leakage rate Q in gap between swash plate _ss(T):

$Q_{\mathrm{ss}}\left(T\right)={\mathrm{\π\δ}}_{\mathrm{ss}}^3\frac{P_p-P_l}{6(a\·e^{\left(\frac{b}{T+c}\right)})\ln \left(\frac{R_{s0}}{R_{s1}}\right)}$

The leakage rate Q of dynamic valve plate oil extraction district's oil sealing band actual cornerite scope inner fluid _vb(T):

Step 5, the dynamically accurately leakage rate in step 4 substituted in the thermal balance equation in step 2, these equations of simultaneous solution, draw the temperature of each temperature node;

Wherein: c _p, c _wbe respectively the specific heat of hydraulic oil and plunger pump shell, m _t, m _p, m _l, m _w, m _cbe respectively the oil quality of oil suction temperature node, oil outlet temperature node, leakage temperature node, case temperature node, inversion temperature node, ρ is hydraulic oil liquid density, and D is ram pump discharge capacity, and ω is ram pump rotating speed, k _fw, k _wabe respectively the same housing of hydraulic oil liquid, housing with the heat transfer coefficient between external environment, A _fwfor hydraulic oil liquid is with contact area heat conducting between housing, A _wafor housing is with contact area heat conducting between external environment, A _cfor hydraulic oil liquid is from oil-discharging cavity to the area of dissipation oil sucting cavity process, L _n, L _d, L _ube respectively the viscous friction loss of ram pump, hydrodynamic force loss and dry friction loss, T _infor fuel tank oil liquid temperature, P _p, P _t, P _c, P _lbe respectively the oil suction pressure of ram pump, oil extraction pressure, transfer pressure, return pressure, V _p, V _t, V _c, V _lbe respectively the fluid specific volume of ram pump oil suction temperature node, oil outlet temperature node, inversion temperature node, leakage temperature node, T _t, T _p, T _l, T _w, T _cbe respectively the temperature of oil suction temperature node, oil outlet temperature node, leakage temperature node, case temperature node, inversion temperature node; α _pfor the volume expansivity of oil outlet temperature node; Q _infor the total flow of ram pump, Q _elfor ram pump external leakage flow, Q _ilfor ram pump internal leakage flow; d _pfor diameter of plunger, δ _pbfor the gap size between plunger and cylinder holes, μ is the kinetic viscosity of fluid, l _pbibe i-th total length between plunger and cylinder holes, v _pbibe the movement velocity of i-th plunger, M is the number of plungers entering oil extraction district, P _pfor the oil suction pressure of ram pump, P _lfor the return pressure of ram pump; Q _vb1for interior oil sealing band leakage flow, Q _vb2for outer oil sealing band leakage flow; R _v1and R _v2for oil sealing band internal diameter and external diameter in valve plate, R _v3and R _v4for the outer oil sealing band internal diameter of valve plate and external diameter; for the actual cornerite of valve plate oil extraction district's oil sealing band, δ _vbfor gap size between valve plate and cylinder body; δ _ssfor the gap size between piston shoes and swash plate, R _s1for piston shoes oil sump radius, R _s0for the maximum exradius of piston shoes, T is the temperature of hydraulic oil liquid.