X-Junk-Score: 0 [] X-Cloudmark-Score: 0 [] X-Cloudmark-Analysis: v=2.2 cv=HLeBLclv c=1 sm=1 tr=0 a=vvnKd497SNCYp8iUn77nsQ==:117 a=vhm3GwjUlMip0Inz7/w+Eg==:17 a=7mUfYlMuFuIA:10 a=r77TgQKjGQsHNAKrUKIA:9 a=z8_eoGVJAAAA:8 a=Ia-xEzejAAAA:8 a=pGLkceISAAAA:8 a=eRLigfuSAAAA:8 a=3oc9M9_CAAAA:8 a=_6GpL_ENAAAA:8 a=MPcV5h1IURFFZe1H1y8A:9 a=X-_pEBiLi5C1NIpA:21 a=gvlRlqd3rJVYx0Gf:21 a=QEXdDO2ut3YA:10 a=I3AUWozZA3TLGo8W2SUA:9 a=GESW63GrSfUg4j3U:21 a=_TG7hiFj5FWg2c-G:21 a=I8dsAvIrOz1f29zc:21 a=_W_S_7VecoQA:10 a=Urk15JJjZg1Xo0ryW_k8:22 a=BfhXYjFvZD4iae-mNffo:22 From: "Ed Anderson eanderson@carolina.rr.com" Received: from [107.14.166.229] (HELO cdptpa-cmomta01.email.rr.com) by logan.com (CommuniGate Pro SMTP 6.2.5) with ESMTPS id 11297943 for flyrotary@lancaironline.net; Sun, 24 Jun 2018 16:36:55 -0400 Received-SPF: pass receiver=logan.com; client-ip=107.14.166.229; envelope-from=eanderson@carolina.rr.com Received: from EdPC ([71.75.201.150]) by cmsmtp with ESMTPA id XBkSfhTOR9qroXBkVfIQmZ; Sun, 24 Jun 2018 20:36:39 +0000 Message-ID: To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Re: Oil Date: Sun, 24 Jun 2018 16:36:38 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_002B_01D40BD9.85FB6180" X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 16.4.3528.331 X-MimeOLE: Produced By Microsoft MimeOLE V16.4.3528.331 X-CMAE-Envelope: MS4wfOFv4ilrOLENiNQ1PUjon+daytK7BYWcOG1fgVaRUWNfx+VKNOvpzosLdyU4Bejn0PrZBVelf9CKQcAnehLAJPtxs1nCHYkOS+9qwYB2/VIaoTLnvpc+ 38qXBDMj1U91sSGnMPEo/Re08PUJLsu+9jKS5v3GV99qwgqX1NiUJoHL5YvlAGi/7q/LZQqyqatv0g== This is a multi-part message in MIME format. ------=_NextPart_000_002B_01D40BD9.85FB6180 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable You said it well, Ernest What you want is heat removal from the engine. Slowing flow down = through a radiator will indeed show a larger Delta T from intake to = outlet because the coolant(in the radiator) is exposed to cooling air = longer. That has led many to believe erroneously that slow flow =3D = more heat removal. I once argued an hour with old man Lou Ross about = this issue and when I told him that the obvious conclusion was that if = slowed water cooled better, then stopped water would cool best =E2=80=93 = there was silence on the other end of the phone and then Lou hung up and = never spoke to me again.=20 Part of the myth also stems the results when attempts were made to = improve flow rate by speeding up the coolant pump expecting better = cooling. When worst cooling occurred, it was concluded erroneously that = the faster flow resulted in worst cooling. In most if not all of those = instances, the poor cooling resulted from less flow =E2=80=93 the faster = water pump was actually cavitating and therefore actually pumping less = coolant than at slower rotating speeds where cavitation did not occur. = But, it all fed into the myth. Heat duty (Q): Heat duty is defined as the product of mass flow rate specific heat capacity and the temperature difference between inlet and outlet fluid temperatures Q =3D m*cp* DT A rule of thumb regarding heat removal and flow rate is: The heat transfer coefficient decreases by =CB=9C10% with a threefold = increase in the mass flow rate=20 reference: https://www.tandfonline.com/doi/abs/10.13182/NT09-A7406 So a 10% decrease in transfer resulting from three times the mass flow = shows that increased mass flow (in of itself) will result in increased = heat removal even though the heat transfer rate may lessen slightly. At some point you get pressure losses and other factors - not to mention = the greatly increased power required to get the large increase in mass = flow - makes it impractical to infinitely increase flow rate. Once you = get the flow good enough to cool your engine under whatever the = conditions you are operating within, it makes little sense to waste = power to get more flow However, we want best heat removal from the engine. Heat is removed via = mass flow of the liquid =E2=80=93 no mass flow =3D no cooling. So the = more mass flow(within reason) - the more heat is removed from the engine = and provided we can get rid of a certain amount of that heat though the = radiator the more cooling of the engine occurs. So it=E2=80=99s a = system, the cooler the oil returned to the engine the better heat = transfer, the more mass flow from engine to radiator the more cooling, = the cooler the air flowing across the radiator the better the heat = rejection, etc. All factors contribute and you can not focus on just = one factor, the optimum cooling results from the optimization of all the = major variables involved for a particular situation. Just my 0.02 Back to my cave Ed . From: mailto:flyrotary@lancaironline.net=20 Sent: Sunday, June 24, 2018 3:41 PM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: Oil Isn't the opposite also true. The most efficient removal of heat from = the back side of the rotor will occur when the oil is the coolest? I suspect that the actual system efficiency curve is very flat. On Sunday, June 24, 2018 2:08 PM, "Charlie England ceengland7@gmail.com" = wrote: First, let me say that I'm far from being an authority on this subject. = The idea of coolant (oil, water, air, etc) moving too quickly through a = heat exchanger comes up often. People who's opinion I trust (trained = engineers) say that slowing flow does not improve efficiency. What I've = been told is that yes, you may see higher delta T across the cooler with = lower flow, but that's not a true and complete picture of what's = happening. My understanding, based on what I've read & been told, is = that the best heat exchange occurs with the max temperature difference = between the media (oil>air, water>air, etc). If you slow the flow = through the exchanger, then yes, you will see a bigger delta T across = the exchanger, but that means that a lot of the oil (in this case) in = the exchanger has already been cooled 'early' in the flow, so = effectively, part of the exchanger is operating at a much lower = temperature difference with the air, and therefore, its efficiency is = reduced. So it follows that higher flow, keeping the entire exchanger = hotter (lower delta T) actually improves efficiency. Yes, it's = counter-intuitive (at least for me). But supposedly, the most BTUs get = removed from the system when the entire exchanger is kept at close to = the same temp across its face. There's obviously a point of diminishing returns, where you're actually = adding heat by overpressurizing the flow path trying to speed up flow, = but I doubt we're there yet. :-) Perhaps a real engineer could step in and clarify. On 6/23/2018 9:35 PM, Andrew Martin andrew@martinag.com.au wrote: Lynn, my setup is pretty much stock where most oil should pass through = cooler direct to rear iron ocv, only oil that enters oil gallery is = filtered, pressure, temp & redrive oil taken from a block after filter,=20 But the cooler issue is a bit more incidious in that without a = pressure gauge at pump outlet there is no indication of the restriction. = I have no problem with having =E2=80=9Csome=E2=80=9D restriction in the = cooler but as it builds markedly with increased flow at rpm, Oil delta t = drops as oil flow is too fast through the core to cool the oil, and when = front cover relief opens at high rpm due to the restriction, only part = of pump output is getting cooled and temps rise more. Setrab, Fluidyne etc do claim low pressure drop but I have struggled = to find at what flow rates, Adding smaller coolers in parallel is an = option but the data is still needed to choose the correct sizes that = allows all oil to pass through a cooler without pressure drop and have = just enough surface area to transfer heat to air. My test showed 140psi pump output 80psi at back iron, I still dont = know what my front cover relief is set at, as 140 was max pressure of = gauge I had. But front cover relief valve should never operate in normal = operation as it is a safety valve for the pump,front cover & cooler = only. Only engine that is diferent is 2009+ renesis as that has only one = valve in the system & diferent oil flow design to the rest of the mazda = rotaries. Andrew On Sun, 24 Jun 2018 at 7:51 am, Accountlehanover lehanover@aol.com = wrote: A restrictive cooler would (might) show a higher oil pressure than = the control valve will allow if measured before the cooler. Because the = stock relief valve is at the end of the system. So the stock valve = might allow for 80 PSI, but never open if the full 80 PSI never gets to = it so as to activate. Racers measure oil pressure where the oil enters = the engine. Usually in an aluminum block that replaces the stock oil = filter stand. What do the bearings see, is the information you want. We raced for = years with 80 PSI entering the engine. And that was turning the engine to 9,000 RPM on each shift. Oil = coolers are constructed of many sharp edged tubes . Pushing oil or any = liquid or gas into the end of a sharp edged tube is nearly impossible. = So many more tubes than you would calculate necessary are used in order = to overcome the sharp tube flow problem. So, if the stock relief were = set at 79 PSI (stock on early engines) you would want to see 79 PSI on = you oil pressure Gage as taken out of that aluminum block. Mistral = calculated the cooler size required on the test Piper. The plane would = overheat the oil while still within sight of the airport. The were also using aircraft oil in the engine. 20-50 if I remember = correctly. So, flow got worse as the oil heated up. The racer had an external oil pump with one pressure section = (adjustable up to any pressure you might want) and two scavenge = sections. The scavenge sections returned oil and air to a storage tank = through a set of bug screen filters and two Setrab 44 row coolers in = series. The pressure section pulled from the tank and pressurized oil = went through two K&N oil filters in parallel and then through a single = 44 row Setrab cooler. So, we ran 100 PSI at the engine. Shifting at = 9,700 RPM. 250 HP. Oil is Red Line 20-50 racing synthetic. A common = choice for rotary racing. Not a single oil related failure in 30 years. = Oil coolers (and filters) in parallel reduce flow resistance. Coolers = and filters in series increase flow resistance. Racing oils collect heat = and give it up more quickly than do conventional oils.So any cooler = performs a bit better with a synthetic. Lynn E. Hanover lehanover@aol.com Any question, any time.=20 In a message dated 6/23/2018 4:59:30 AM Eastern Standard Time, = flyrotary@lancaironline.net writes:=20 Just got around to plumbing in mechanical gauge before cooler to = see whats really happening with my oil flows, wish I=E2=80=99d done it = years ago! Learnt so much in a couple of minutes on things that I have = wasted so much time second guessing. my second attempt oil cooler did = work better than the original mazda cooler, but was atrocious overall, = Pressure drop was about 60psi at 1400 prop rpm. No wonder I cant cool = the oil, bugger all is going through it, just enough to give me about = 80psi oil pressure. Ended up bypassing cooler all together to confirm it is the cooler = that is problem not lines or anything else, well what a diference = pressures constant at 78psi at all rpm=E2=80=99s Trouble is no cooler manufacturer here seems to have charts of = flow & pressure drop on their coolers, very frustrating especially as = prices seem to range between $100-900 for similar sizes, so makes it = very hard to select correct one. Andrew --=20 Regards Andrew Martin Martin Ag --=20 Regards Andrew Martin Martin Ag Virus-free. www.avast.com =20 ------=_NextPart_000_002B_01D40BD9.85FB6180 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
You said it well, Ernest
 
What you want is heat removal from the engine.  Slowing flow = down=20 through a radiator will indeed show a larger Delta T from intake to = outlet=20 because the coolant(in the radiator) is exposed to cooling air = longer. =20 That has led many to believe erroneously that slow flow =3D more heat=20 removal.  I once argued an hour with old man Lou Ross about this = issue and=20 when I told him that the obvious conclusion was that if slowed water = cooled=20 better, then stopped water would cool best =E2=80=93 there was silence = on the other end=20 of the phone and then Lou hung up and never spoke to me again.
 
Part of the myth also stems the results when attempts were made to = improve=20 flow rate by speeding up the coolant pump expecting better = cooling.  When=20 worst cooling occurred, it was concluded erroneously that the faster = flow=20 resulted in worst cooling. In most if not all of those instances, the = poor=20 cooling resulted from less flow =E2=80=93 the faster water pump was = actually cavitating=20 and therefore actually pumping less coolant than at slower rotating = speeds where=20 cavitation did not occur.  But, it all fed into the myth.
 
 
Heat duty (Q): Heat duty is defined as the product of mass = flow
rate specific heat capacity and the temperature difference
between inlet and outlet fluid temperatures
 
Q =3D m*cp* DT
 
A rule of thumb regarding heat removal and flow rate is:
 
The heat transfer = coefficient=20 decreases by =CB=9C10% with a threefold increase in the mass flow = rate=20
 
reference:  https://= www.tandfonline.com/doi/abs/10.13182/NT09-A7406
 
 
So a 10% decrease in transfer resulting from  three times the = mass=20 flow shows that increased mass flow (in of itself) will result in = increased heat=20 removal even though the heat transfer rate may lessen slightly.
 
At some point you get pressure losses and other factors - not to = mention=20 the greatly increased power required to get the large increase in mass = flow -=20 makes it impractical to infinitely increase flow rate.  Once you = get the=20 flow good enough to cool your engine under whatever the conditions you = are=20 operating within, it makes little sense to waste power to get more = flow
 
However, we want best heat removal from the engine.  Heat is = removed=20 via mass flow of the liquid =E2=80=93 no mass flow =3D no cooling.  = So the more mass=20 flow(within reason) - the more heat is removed from the engine and = provided we=20 can get rid of a certain amount of that heat though the radiator the = more=20 cooling of the engine occurs. So it=E2=80=99s a system, the cooler the = oil returned to=20 the engine the better heat transfer, the more mass flow from engine to = radiator=20 the more cooling, the cooler the air flowing across the radiator the = better the=20 heat rejection, etc.  All factors contribute and you can not focus = on just=20 one factor, the optimum cooling results from the optimization of all the = major=20 variables involved for a particular situation.
 
Just my 0.02  Back to my cave
 
Ed
 
 
.
 
Sent: Sunday, June 24, 2018 3:41 PM
Subject: [FlyRotary] Re: Oil
 
Isn't the opposite also true.  The most efficient = removal of=20 heat from the back side of the rotor will occur when the oil is the=20 coolest?

I suspect that the actual system efficiency curve is very=20 flat.


On Sunday, June 24, 2018 2:08 = PM, "Charlie=20 England ceengland7@gmail.com" <flyrotary@lancaironline.net>=20 wrote:


First, let me say that I'm far = from=20 being an authority on this subject. 

The idea of coolant = (oil,=20 water, air, etc) moving too quickly through a heat exchanger comes up = often.=20 People who's opinion I trust (trained engineers) say that slowing flow = does not=20 improve efficiency. What I've been told is that yes, you may see higher = delta T=20 across the cooler with lower flow, but that's not a true and complete = picture of=20 what's happening. My understanding, based on what I've read & been = told, is=20 that the best heat exchange occurs with the max temperature difference = between=20 the media (oil>air, water>air, etc). If you slow the flow through = the=20 exchanger, then yes, you will see a bigger delta T across the exchanger, = but=20 that means that a lot of the oil (in this case) in the exchanger has = already=20 been cooled 'early' in the flow, so effectively, part of the exchanger = is=20 operating at a much lower temperature difference with the air, and = therefore,=20 its efficiency is reduced. So it follows that higher flow, keeping the = entire=20 exchanger hotter (lower delta T) actually improves efficiency. Yes, it's = counter-intuitive (at least for me). But supposedly, the most BTUs get = removed=20 from the system when the entire exchanger is kept at close to the same = temp=20 across its face.

There's obviously a point of diminishing = returns, where=20 you're actually adding heat by overpressurizing the flow path trying to = speed up=20 flow, but I doubt we're there yet. :-)

Perhaps a real engineer = could step=20 in and clarify.

On 6/23/2018 9:35 PM, Andrew Martin andrew@martinag.com.au=20 wrote:
Lynn, my setup is pretty much stock where most oil should pass = through=20 cooler direct to rear iron ocv, only oil that enters oil gallery is = filtered,=20 pressure, temp & redrive oil taken from a block after filter, =
But the cooler issue is a bit more incidious in that without a = pressure=20 gauge at pump outlet there is no indication of the restriction. I have = no=20 problem with having =E2=80=9Csome=E2=80=9D restriction in the cooler = but as it builds markedly=20 with increased flow at rpm, Oil delta t drops as oil flow is too fast = through=20 the core to cool the oil, and when front cover relief opens at high = rpm due to=20 the restriction, only part of pump output is getting cooled and temps = rise=20 more.
Setrab, Fluidyne etc do claim low pressure drop but I have = struggled to=20 find at what flow rates, Adding smaller coolers in parallel is an = option but=20 the data is still needed to choose the correct sizes that allows all = oil to=20 pass through a cooler without pressure drop and have just enough = surface area=20 to transfer heat to air.
My test showed 140psi pump output 80psi at back iron, I still = dont know=20 what my front cover relief is set at, as 140 was max pressure of gauge = I had.=20 But front cover relief valve should never operate in normal operation = as it is=20 a safety valve for the pump,front cover & cooler only.
Only engine that is diferent is 2009+ renesis as that has only = one valve=20 in the system & diferent oil flow design to the rest of the mazda=20 rotaries.
 
Andrew
 
On Sun, 24 Jun 2018 at 7:51 am, Accountlehanover lehanover@aol.com <flyrotary@lancaironline.ne= t>=20 wrote:
 =20 A restrictive cooler would (might) show a higher oil pressure than = the=20 control valve will allow if measured before the cooler. Because the = stock=20 relief valve is at  the end of the system. So the stock valve = might=20 allow for 80 PSI, but never open if the full 80 PSI never gets to it = so as=20 to activate. Racers measure oil pressure where the oil enters the = engine.=20 Usually in an aluminum block that replaces the stock oil filter=20 stand.
What=20 do the bearings see, is the information you want. We raced for years = with 80=20 PSI entering the engine.
And=20 that was turning the engine to 9,000 RPM on each shift. Oil coolers = are=20 constructed of many sharp edged tubes . Pushing oil or any liquid or = gas=20 into the end of a sharp edged tube is nearly impossible. So many = more tubes=20 than you would calculate necessary are used in order to overcome the = sharp=20 tube flow problem.  So,=20 if the stock relief were set at 79 PSI (stock on early = engines) you=20 would want to see 79 PSI on you oil pressure Gage as taken out of = that=20 aluminum block. Mistral calculated the cooler size required on the = test=20 Piper. The plane would overheat the oil while still within sight of = the=20 airport.
The=20 were also using aircraft oil in the engine. 20-50 if I remember = correctly.=20 So, flow got worse as the oil heated up.
 
The=20 racer had an external oil pump with one pressure section (adjustable = up to=20 any pressure you might want) and two scavenge sections. The scavenge = sections returned oil and air to a storage tank through a set of bug = screen=20 filters and two Setrab 44 row coolers in series. The pressure = section pulled=20 from the tank and pressurized oil went through two K&N oil = filters in=20 parallel and then through a single 44 row Setrab cooler. So, we ran = 100 PSI=20 at the engine. Shifting at 9,700 RPM. 250 HP.  Oil is Red Line = 20-50=20 racing synthetic.  A common choice for rotary racing. Not a = single oil=20 related failure in 30 years. Oil coolers (and filters) in parallel = reduce=20 flow resistance. Coolers and filters in series increase flow = resistance.=20 Racing oils collect heat and give it up more quickly than do = conventional=20 oils.So any cooler performs a bit better with a = synthetic.
 
Lynn=20 E. Hanover
lehanover@aol.com
Any=20 question, any time.
 
 
In a message dated 6/23/2018 4:59:30 AM Eastern Standard Time, = flyrotary@lancaironline.ne= t=20 writes:=20
 
Just got around to plumbing in mechanical gauge before cooler = to see=20 whats really happening with my oil flows, wish I=E2=80=99d done it = years ago!=20 Learnt so much in a couple of minutes on things that I have wasted = so much=20 time second guessing. my second attempt oil cooler did work better = than=20 the original mazda cooler, but was atrocious overall, Pressure = drop was=20 about 60psi at 1400 prop rpm. No wonder I cant cool the oil, = bugger all is=20 going through it, just enough to give me about 80psi oil = pressure.
Ended up bypassing cooler all together to confirm it is the = cooler=20 that is problem not lines or anything else, well what a diference=20 pressures constant at 78psi at all rpm=E2=80=99s
 
Trouble is no cooler manufacturer here seems to have charts = of flow=20 & pressure drop on their coolers, very frustrating especially = as=20 prices seem to range between $100-900 for similar sizes, so makes = it very=20 hard to select correct one.
Andrew
--
Regards Andrew Martin Martin=20 Ag
-- =
Regards Andrew = Martin Martin=20 Ag


Virus-free.=20 www.avast.com=20
3D""=20


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