Pressure reducing device for gaseous fuel system
A pressure reducing device is disclosed for use with a gaseous fuel system. The pressure reducing device may include a body defining an inlet and an outlet, and a converging-diverging nozzle formed between the inlet and the outlet. The pressure reducing device may further include a shockwave inducing element disposed within the body between the venture and the outlet, and an airfoil located inside the body upstream of the shockwave inducing element and connected to move the shockwave inducing element.
1. A pressure reducing device, comprising:
a body defining an inlet and an outlet;
a converging-diverging nozzle formed between the inlet and the outlet;
a shockwave inducing element disposed within the body between the converging-diverging nozzle and the outlet; and
an airfoil located inside the body upstream of the shockwave inducing element and connected to move the shockwave inducing element, wherein the shockwave inducing element is configured to produce an oblique shockwave within the body that creates a pressure drop and a temperature increase in a flow of fluid at the outlet.
2. The pressure reducing device of claim 1 , wherein the shockwave inducing element is a ramp having a first end pivotally connected at an upstream end to a wall of the body.
3. The pressure reducing device of claim 2 , wherein a greater pressure in the flow of fluid through the converging-diverging nozzle results in the ramp pivoting to a greater angle away from the wall of the body.
4. The pressure reducing device of claim 2 , wherein the ramp is biased toward the wall of the body.
5. The pressure reducing device of claim 4 , further including:
linkage connecting the airfoil to a second end of the ramp opposite the first end; and
a spring connected to the linkage to bias the ramp.
6. The pressure reducing device of claim 5 , wherein the airfoil is biased toward the wall of the body by the spring, and movable toward a center axis of the body by a flow of fluid passing over the airfoil.
7. The pressure reducing device of claim 5 , wherein:
the airfoil is fixedly connected to the linkage; and
the ramp is pivotally connected to the linkage.
8. The pressure reducing device of claim 7 , wherein the linkage includes an end pivotally connected to the body.
9. The pressure reducing device of claim 8 , wherein the airfoil is connected to the linkage at a location between the end and the ramp.
10. The pressure reducing device of claim 1 , wherein a higher pressure at the inlet results in a steeper angle of the oblique shockwave and a greater pressure drop at the outlet.
11. A fuel system for an engine, comprising:
a supply of liquid fuel;
a pump configured to draw fuel from the supply;
an accumulator located downstream of the pump and configured to store gasified fuel; and
a pressure reducing device fluidly connected to the accumulator, the pressure reducing device including:
a body defining an inlet and an outlet;
a converging-diverging nozzle formed between the inlet and the outlet;
a ramp disposed within the body between the converging-diverging nozzle and the outlet, the ramp having a first end pivotally connected to a wall of the body, and a second end;
an airfoil located inside the body upstream of the ramp;
linkage connecting the airfoil to the second end of the ramp; and
a spring biasing the airfoil and the ramp toward the wall of the body.
12. The fuel system of claim 11 , wherein the ramp is configured to produce an oblique shockwave within the body that creates a pressure drop and a temperature increase in a flow of gaseous fuel at the outlet.
13. The fuel system of claim 12 , wherein a higher pressure at the inlet results in a steeper angle of the oblique shockwave and a greater pressure drop at the outlet.
14. The fuel system of claim 11 , wherein the pressure reducing device is a vent connected to the accumulator.
15. The fuel system of claim 11 , wherein the pressure reducing device is a regulator connected between the accumulator and the engine.
16. A method of regulating gaseous fuel pressures for an engine, comprising:
directing gaseous fuel through a converging-diverging nozzle; and
generating an oblique shockwave in the gaseous fuel at a location downstream of the converging-diverging nozzle to cause a pressure drop in the gaseous fuel, wherein generating the oblique shockwave includes directing the gaseous fuel from the converging-diverging nozzle against a ramp extending out into a flow of the gaseous fuel.
17. The method of claim 16 , further including adjusting an attack angle of an airfoil to vary the pressure drop.
18. The method of claim 16 , further including directing the gaseous fuel from the converging-diverging nozzle over an airfoil at a location upstream of the ramp to vary an angle of the ramp and the oblique shockwave.