The technical field to which this invention pertains is gas turbine engines, particularly handling bleed valves for gas turbine engines.
In gas turbine engines for use in powering aircraft, air is directed through multiple stage compressors as it flows axially or axially and radially through the engine to a combuster. As the air passes through each successive compressor stage, the pressure of the air is increased. Under certain conditions, such as when the engine is operating at off design conditions, interstage bleed is required to match the compressor stages. If this compressor matching is not acheived an engine surge or blow-out may occur, endangering the operation of the engine and the associated aircraft.
To mitigate against these conditions, such gas turbine engines have incorporated bleed valves in the engine casing forward of the burner which, when an engine surge is imminent, open to rematch the compressor stages. These bleed valves have taken many forms from simple ports in the compressor casing which open via a movable valve element to devices which separate adjacent segments of the engine casing thereby creating an opening there between.
However, these valves, although useful, present problems where the air bleed off is directed into a secondary air flow, in lieu of being dumped overboard. In the design of these prior art bleed valves all of the criteria which must be met such as, simple maintenance of the valve, maintenance of a smooth fluid flow through the bypass flow path and quick response time are not all addressed in any single prior art valve.
Therefore, what is necessary in this art is a bleed valve that is simple to service, minimizes the disturbance to the secondary air flow and offers quick response to the pressure changes which lead to the engine operating problems.
The present invention discloses a bleed valve for use in a gas turbine engine in which a housing is positioned on the outboard perimeter of a bypass fluid flow path. A piston having a first end is fitted into said housing and extends across the by pass fluid flow path to a barrier separating the by pass fluid flow path from a primary fluid flow path. The piston having a second end opposite to the first end is sealably fitted into an opening in the barrier and wherein the piston is slidably movable to seal and unseal the opening in response to a pressure differential between the two locations in the primary fluid flow path.
This invention will permit the use of a bypass valve which will respond to prevent surges in the engine and will be easily serviced without disassembly of the engine due to its positioning across the by pass flow path and having the housing on the perimeter of the by pass flow path.
FIG. 1 is a view of one embodiment of the valve of the present invention indicating its location in a gas turbine engine.
FIG. 2 is a breakaway view of one embodiment of the valve of the present invention depicting the valve in the closed position
FIG. 3 is a breakaway view of one embodiment of the valve of the present invention depicting the valve in the open position.
FIG. 4 is a cross sectional view of one embodiment of a valve of the present invention positioned in a gas turbine engine in the open position.
FIG. 4A is a cross sectional view of the valve showing the pressure control means.
FIG. 5 is a cross sectional view of one embodiment of a valve of the present invention positioned in a gas turbine engine in the closed position.
FIG. 6 is a cross sectional view of taken along line 6--6 of FIG. 2 of the piston central portion and strut member.
The bleed valve of the present invention will be described herein with reference to FIGS. 1-6. The description and the drawings are intended to be exemplary and not limiting.
Referring now to the Figures in which the bleed valve of the present invention is shown. The bleed valve 2 comprises a piston 4 having a first end 6 and a second end 8 connected by a center portion 10. The first end 6 is fitted into a chamber 12 inside a housing 14. The housing 14 is fitted into an opening 16 in the outer perimeter of the by bypass flow path, in this case the outer shroud 18 of the engine 20. The chamber 12 of the housing 14 is in flow or pressure communication with one location within a primary flow path 22 of compressed gas passing through the engine 20. Via an opening 24 in the housing 14 a controlling pressure is introduced to schedule the valve opening.
In the present description the housing 14 is formed of a single unit which is attached to the outer shroud 18 by a number of bolts 26 and which is seated onto a flange 28 on the perimeter of the opening 16. The piston 4 is slidably mounted onto a rod or similar means 29 which passes longitudinally through substantially the center of the piston 4.
The second end 8 is formed such that it will seat in and seal an opening 30 in a barrier separating the bypass flow path 34 from the primary flow path 22, in the present embodiment this is the inner shroud 32, and thereby prevent any of the primary fluid flow 22 to pass to the bypass fluid flow path 34 through said opening 30 when the piston 4 is in the closed position. This may be achieved in any number of designs.
The present embodiment depicts an aerodynamic design for the second end 8 in which the top 35 of the second end 8 is smooth and forms a smooth plane with the surface of the inner shroud 32 when the valve 2 is in the closed position as shown in FIGS. 2 and 5. However, that portion of the second end 8 which is below the inner shroud 32 when the valve 2 is in the closed position, the bottom 36 of the second end 8, is downwardly inwardly frustoconically tapered. Although it is not necessary that the bottom 36 be formed in such a manner, it is preferred that it be formed in such a shape so as to permit an even transition zone for the fluid to flow from the primary flow path 22 into the bypass flow path 34, and to control the rate of opening and closing of the valve.
In addition, a portion of the bottom 36 which is facing upstream of the bypass fluid flow path 34, is in the form of an arcuate apron 38 extending around the leading edge 40 of the circumference 42 of the second end 8, from about one side 44 of the second end 8 of the piston to the opposite side 46 of the second end 8 of the piston and crossing the plane perpendicular to the bypass flow path 34. The apron 38 further extends from just under the top of the second end 8 to just below the inner shroud 32 when the valve 2 is in the open position (See FIG. 3). This apron 38 prevents bleed flow exit in the upstream direction of the by-pass flow. Such a flow will disturb the fan by affecting its stability, reducing surge margin and increasing noise level.
As depicted in FIG. 4 and 5 the opening 30 in the inner shroud 32 houses the structural framework 48 to support the rod 29 on which the piston 4 is slidably fitted. The rod 29 is removably connected to the structural framework 48 by a nut 50 threaded onto the end 52 of the rod 29 and the other end of the rod 29 is removably fixed in the same manner to an opening in the housing 14 by a nut 57. Bushings 54 are introduced between the rod 29 and the piston 4 to ensure free sliding movement of the piston 4. A compression spring 56 is fitted on to rod 29 at the end 52 between the structural framework 48 and piston end 8 to ensure that with no pressures acting on the piston 4, the piston 4 will remain in a partly open condition. This valve position will enhance engine starting.
Additionally the upstream surface 58 of the piston having central portion 10 may be fitted with a slot 60 which slides over a key 61 which is attached to housing 14. The upstream surface 58 of the piston central portion 10 may be designed in the form of an aerodynamic shape in combination with the strut 64 as shown in FIG. 6, thereby reducing the disturbance in the bypass flow path 34. The key 61 and the slot 60 provide an antirotation means to ensure alignment of the strut 64 and the piston central portion 10. This also acts as an antirotation feature to insure alignment of the apron 38 and piston central portion 10.
The bleed valve responds to a preset pressure differential between a first location in the primary fluid flow path 22 and a second location in the primary flow path 22 such that as the pressure in the second location, which is in pressure communication with the chamber 12 in the housing 14 in which the first end 6 of the piston 4 is fitted, is greater than the pressure at the first location, which is in pressure and flow communication with the primary fluid flow path 22, the valve 4 remains in the closed position and none of the fluid of the primary fluid flow path 22 is permitted to pass from the primary fluid flow path 22 to the bypass fluid flow path 34. However, in the event that the pressure at the first location is greater than the second location by a predetermined amount, then the pressure in the chamber 12 of the housing 14 is less than that at the opening 30 of the inner shroud 32 and the piston 4 is slidably moved up the rod 29 thereby moving the second end 8 of the piston 4 into a position where it no longer seals the opening 30 in the inner shroud 32 and thereby permitting a portion of the primary fluid flow 22 to pass through the opening 30 in the inner shroud 32 to the bypass fluid flow path 34.
As may be seen by viewing FIG. 4A the pressure from the first location is upstream from the maximum compressor outlet for the primary flow path 22, while the second location is downstream from the maximum compressor outlet and is in flow communication via a tube (partially indicated at 66). The tube is fitted with an orifice 68 (this may be an adjustible valve i.e. needle valve or a simple hole of a predetermined size) and connects with a second tube 70 forming a T or Y having one end connected to the housing at opening 24 and the other end 72 vented to atmosphere through an orifice 73. In addition, PG,7 a regulating means 74 is fitted between the orifices 68 and 73 to control the valve opening to a certain compressor speed. The pressure created at opening 24 will be such that the valve will have a predetermined position as a function of compressor rotational speed, thereby bleeding as required and hence preventing surge.
The present invention offers a bleed valve for use in bypass engines having unique and beneficial advantages not seen in the prior art. The present invention discloses a bleed valve which is releasably mounted on the exterior of the engine to permit easy removal and maintenance without the disassembly of the engine as necessitated by prior designs. In addition the valve offers a minimum disturbance to the flow path of the bypass flow and therefore lessens any loss of efficiency due to the placement of such a device across the flow path of the bypass fluid.
While the particular invention has been described with reference to illustrated embodiments, this description is not meant to be construed as limiting. It is understood that although the present invention has been described in a preferred embodiment, various modifications of the illustrated embodiments as well as additional embodiments of the invention, will be apparent to persons of ordinary skill in this art without departing from the spirit of this invention. It is therefore contemplated that the appended claims.
A bleed valve is a valve that typically utilizes a threaded bleed screw to open or close. Generally, these valves vent pressure or release media from within a system. This is often necessary before starting maintenance work on a line that contains pressurized liquids or gasses.How is each bleed valve controlled and operated? ›
Each bleed valve is pneumatically operated and controlled electrically by its associated BMC.Where is a bleed valve needed? ›
A bleed Valve should be installed between the outlet isolation Valve and pressure-relief device to enable the system to be safely depressurized prior to performing maintenance. This bleed Valve can also be used to prevent pressure build-up between the pressure-relief device and the closed outlet isolation Valve.What is a bleed air valve? ›
A bleed air system uses a network of ducts, valves and regulators to conduct medium to high pressure air, "bled" from the compressor section of the engine(s) and APU, to various locations within the aircraft. There it is utilized for a number of functions inclusive of: pressurisation. air conditioning.What is a bleed valve called? ›
An automatic bleeding valve or air release valve (ARV) is a plumbing valve used to automatically release trapped air from a heating system.How do you turn a bleed valve on? ›
You can use a flathead screwdriver to bleed a radiator without a key. Place the flat head into the notches of the bleed valve. To bleed the radiator, turn anticlockwise to open the valve, and clockwise to close the valve. Remember to hold an old cloth or jug under the bleed valve to catch any escaping water.What 3 ways can control valve be operated? ›
Control valve operation
The actuator is the device connected to the valve through the valve stem that provides the force required to move the valve. As we said earlier, the actuator can be controlled electrically, pneumatically, or hydraulically. The most common and the most reliable is the “Pneumatic Actuator”.
A minimum pressure of 8 psig is necessary to open the valve.Do I leave bleeder valve open? ›
After the supply line is empty, drained of water, it is not necessary to leave the bleeder port open as the line has been drained. You can go close the hose bib and then go back and close the bleeder port, as it has served its purpose, but leave the valve it is on closed so no water will supplied to the hose bib.How do you bleed without a bleeder valve? ›
Most definitely, you can bleed the brakes of your vehicle from the brake line. You have to detach the brake line fixed to the brake caliper. After that, put the end of the brake line inside a can containing brake fluid. Then then you get an assistant to help you apply pressure on the brake pedals of your vehicle.
The bleeder valve will close when the temperature of the water or fluid is above the set point and the danger of freezing is over. Drain valves are typically positive action valves that open or release at a set temperature.What does a bleed valve look like? ›
Tip: Every radiator has a bleed valve. They're typically located at the top corner of a radiator and look like a round hole with a square inside. If no water or air comes out when you bleed the radiator, then the valve could be blocked with paint.Why is my bleed valve leaking? ›
Bleed valves are very common sources for a leaky radiator and relatively easy to put right. They tend to come about because the spindle-packing inside the little bit of radiator kit that's the valve has got damaged or may have worn out.Is bleed air toxic? ›
Fumes and Fume Events
In the case of contaminated air inside an aircraft cockpit/cabin, the term “fume event” has been used to refer to a potentially toxic environment created by contaminated bleed air .
There are three main types of bleeding: arterial, venous, and capillary bleeding. These get their names from the blood vessel that the blood comes from. Additionally, bleeding can be either external, such as what comes from a minor skin scrape, or internal, such as what comes from an injury to an organ or bone.What is the difference between bleed and slug? ›
The main difference between a bleed and a slug is their respective functions. A bleed is often used intentionally and unintentionally. Meanwhile, a slug is used as a tool to impart various types of written instruction to the paper's recipients.How do block and bleed valves work? ›
Double block and bleed (DBB) is the practice of shutting in a section of pipe on both sides of the valve rather than just one. It means you close the ball valves to block both the upstream and downstream sides of your working area, and then bleed any pressure that remains in the piping and valve.How do you check a bleeder valve? ›
The bleed valve can usually be found at the top of a radiator, at one of the sides. On older radiators, it often has the appearance of a round hole with a square inside, while on more modern designs it looks more like a nut with a screw in the centre.How do bleeders work? ›
Simply put, speed bleeders replace the original bleeder in your brake caliper. They contain a small ball and spring that pushes up to release the air and old fluid when you pump the brakes, and then automatically closes back down to prevent the old fluid and air from re-entering.Which radiator do I bleed first? ›
The radiator to bleed first
Making sure your central heating is switched off, you should start with a downstairs radiator that is the furthest away from your boiler. Work your way through the radiators getting closer to the boiler, then go upstairs and repeat the process.
- Ball Valves. Ball valves use a spherical plug design that contains a bored-in passage. ...
- Check Valves. These types of valves prevent the reversal of fluid flow in piping. ...
- Butterfly Valves. ...
- Gate Valves. ...
- Globe Valves. ...
- Needle Valves.
Control valves and on-off valves serve different purposes depending on the degree of control you need for your system. Control valves are more precise, whereas on-off valves are more all-or-nothing.What are the 4 different valves? ›
- tricuspid valve: located between the right atrium and the right ventricle.
- pulmonary valve: located between the right ventricle and the pulmonary artery.
- mitral valve: located between the left atrium and the left ventricle.
- aortic valve: located between the left ventricle and the aorta.
- Atresia is a heart condition that may be present at birth (called a congenital heart defect) or, rarely, acquired later in life. ...
- Regurgitation, also known as backflow or insufficiency, happens when a valve does not seal tightly.
Three-way, 2-position valves typically feature a three-ported design allowing flow paths in several different configurations, while only connecting two ports in any single position. The valve consists of a series of tapered cylinders with diameters that get smaller from top to bottom.Do you have to open bleeder valve to compress piston? ›
From an expert point of view, it is necessary to open the bleeder valve to compress the caliper piston. It is not advisable to compress your brake caliper without bleeding. You should know that if you don't open the bleeder valve, the brake fluid in the caliper will have a very high risk of getting contaminated.How does bleed air start an engine? ›
Through the opening of bleed air valves, bleed air is sent to an air turbine starter. These devices typically use the high pressure bleed air to spin and engage a centrifugal clutch connected to the engines accessory drive. This in turn causes the N2 shaft within the engine to spin.At what PSI does the safety valve open? ›
It is usually set to open at 150 psi. If the valve must open, there is a fault in the system that should be repaired by a mechanic.How tight should a bleeder valve be? ›
One word of warning here - Don't tighten your bleeder screw with a ratchet. The recommended torque figures for bleeder screws are between 6 lbs-ft to 10 lbs-ft (8 - 13 N-m). You could generate that much torque through a standard 8" long ratchet if you put two fingers on the handle and gave it a gentle squeeze.When bleeding brakes do you leave the cap on or off? ›
During brake bleeding, the master-cylinder cap should be left unscrewed but still in place atop the reservoir. Each brake must be bled in the correct sequence. Generally, you bleed the brake most distant from the master cylinder first, but some cars require a different order.
Over time, air can become trapped within your radiators, leading to cold spots and a less-than-optimal performance from your home heating devices. If you don't bleed your radiators, the issue will worsen over time.Can you bleed brakes by gravity? ›
Gravity is good
Gravity is the simplest one-person brake bleeding method. Attach the hose to the bleed screw, open it up, and watch old brake fluid and air flow out of the lines like water through the Aqua Virgo aqueduct on the way to Rome. These inexpensive Bleed-O-Matic type setups work well.
Unexplained and excessive bleeding from cuts or injuries, or after surgery or dental work. Many large or deep bruises. Unusual bleeding after vaccinations. Pain, swelling or tightness in your joints.What is the best method to bleed brakes? ›
Reverse bleeding is the absolute best single brake bleeding method to use. It is the most effective at removing trapped air. It works well with ABS equipped vehicles as well as any vehicle with a bleed screw. It is very quick, the fastest of any bleeding method.Can you replace bleed valve? ›
The bleed valve is one of the easiest valves to change on a radiator - no need to drain the system or the radiator - and shouldn't take more than 10 minutes. You just need to know a few trade secrets. Be prepared: It's likely that there will be a little bit of water loss so preparation is key.What is single block and bleed valve? ›
Single block and bleed valves are used to achieve positive isolation when performing maintenance activities in a live process plant. Typically one block valve and a bleed valve are manufactured as a single assembly and this block and bleed valve manifold can be readily installed for isolation purpose.Does OSHA require double block and bleed? ›
When chemical or gas lines are connected to a permit space, they must be isolated by such means as blanking or blinding, misaligning or removing section of lines, pipes, or ducts, or a double block and bleed system.What happens if you let too much water out of a radiator? ›
Baird warns that letting out too much water is likely to introduce fresh water into the system, which can make the situation worse as fresh water contains a lot of air. He adds: “Some people also think if a radiator is cold on the bottom but hot at the top then it needs to be bled.Should radiators be too hot to touch? ›
Are hot radiators unsafe? There's radiators that get hot enough to adequately heat the room and then there's radiators that are too hot to touch and pumping out far too much heat. If your radiators are too hot to the touch then this is of concern, especially if you have young children.How do I fix a leaky bleeder valve? ›
- Clean the bleed valve. Remove any brake fluid residue off the threads using soapy water and dry with a cloth.
- Remove the bleeder screw. Unscrew the bleeder screw from the wheel cylinder.
- Apply the thread sealant. ...
A bleed air system uses a network of ducts, valves and regulators to conduct medium to high pressure air, "bled" from the compressor section of the engine(s) and APU, to various locations within the aircraft.Is bleed air hot or cold? ›
Bleed air is useful in an aircraft because of two properties: high temperature (typically 200 – 250 degrees C.) and moderate pressure (regulated to approximately 40 PSI exiting the engine pylon). This hot, compressed air can be used in many different ways.What is the purpose of bleed air? ›
Bleed air can be used to heat the engine inlets to prevent ice from forming, detaching and being ingested into the engine. Similarly, this warm air can be used to prevent ice build-up on the leading edges of the wings. Bleed air is also sometimes used for starting one of the aircraft's engines.What are the two types of flow control valve? ›
The most common valve types in flow control industries include: Gate valves. Globe valves.How does a brake bleeder valve work? ›
Brake bleeders work by exerting pressure on the bleed valve which helps the fluid to come out more easily. Normally, you would need to have someone sat in the car to pump the brake pedal whilst you drain the fluid from the wheel end.How do radiator bleed valves work? ›
The purpose of the bleed valve is to release air that sometimes gets trapped inside radiators, making them less efficient. The valve comprises a plug that screws into a radiator tapping at the top of the radiator, and an adjustable bleed screw, with a 5mm square head, in its centre.What are the 5 types of check valves? ›
Most common types of Check valves are swing, lift (piston and ball), butterfly, stop and tilting-disk.What are the 3 types of flow? ›
Key Takeaways. There are three fluid flow regimes: laminar, turbulent, and a transition region. The conditions that lead to each type of flow behavior are system-specific.Why is it called 3 2 valve? ›
A 3/2-way valve has three ports and two positions that can be driven pneumatically, mechanically, manually or electrically via a solenoid valve. They are used, for example, to control a single-action cylinder, driving pneumatic actuators, blow-off, pressure release and vacuum applications.What is the difference between flow valve and flow control valve? ›
The flow valve does the same thing, the difference is that it sends signals to a flow transmitter. The flow transmitter will then communicate with the flow control valve to tell it whether it needs to open or close based on the amount of liquid that is required to keep the hydraulic system working.
The bleeder might be located, e.g. on the bottom of the supply valve, such that any leakage at the supply valve will immediately run out of the bleeder. You'll need to leave it closed or arrange for safe drainage.Can you over tighten a radiator bleed valve? ›
Re-tighten the bleed valve by turning the radiator key clockwise; make sure you don't over-tighten it. Check your boiler pressure. Bleeding radiators can cause your pressure to drop so it's best to check your boiler pressure gauge. The dial on the gauge should be between 1 and 2 (in the green zone.)Should you bleed radiators with heating on or off? ›
You must not bleed a radiator when the heating is turned on as it may be too hot to touch and hot water could spray out of it. Ensure the heating is turned off before you begin bleeding a radiator. Letting out air when the pump is running will only draw more air into the system from elsewhere.