Patent Description:
In a centrifugal compressor, since there may be a sharp rise in temperature after the gas is compressed, and there is a great gas specific volume at a high temperature, the energy consumption of the compressor will increase sharply in the case that the same cooling capacity is ensured. In order to reduce the power consumption of the compressor and improve the cooling capacity, a multi-stage compression refrigeration cycle is commonly used.

At present, the most widely used is the "double-stage compression refrigeration cycle with an intermediate incomplete cooling", in which a flash steam separator (commonly known as an economizer) is provided. The double-stage compression refrigeration cycle mixes the flash steam separated from the economizer with the exhaust gas from the low-stage compression such that the intake air temperature of the secondary compression is reduced, the gas specific volume of the refrigerant is lowered, and the energy consumption of the compressor is reduced. However, due to a difference in the magnitude and direction of the airflow speed between the main stream and the gas supplement stream, the current gas supplement solution results in a large airflow mixing loss and the aerodynamic efficiency of the compressor is reduced.

In addition, in the centrifugal compressor, the aerodynamic performance of the compressor at a design point may be effectively improved by using a vaned diffuser. However, when the working condition deviates from the design point, as the inlet airflow angle of the diffuser vane varies, it results in that the vane produces a large low-speed and low-energy area, which finally leads to stall and surge of the compressor and reduces a stable operating range of the compressor. By using a vaneless diffuser, although the compressor has a wide operating range, there is a low design-point performance.

There have been several patents or applications that cover variations of the diffuser vane, the compressor structure and the compressor. For example, the patent No. <CIT> discloses a fluid machine containing a flow of fluid comprising a plurality of sets of curved blades, a casing to conduct fluid from one set of blades to another set, each set serving to alter the local direction of flow and to direct the flow through the machine, one set of blades being rotatable relative to the other set, the blades of at least one set having openings in their surfaces in communication with their interiors and means to admit fluid impelled by one set of blades to the blade interiors of the other set for discharge through their said openings to energize the boundary layer on the surfaces of the blades.

<CIT> discloses a multistage compressor including a pore portion provided on a part of a wall of the flow passage between the stages and a liquid supply part immersing liquid into the flow passage through the pore portion. The pore portion is provided in a diffuser that converts the velocity energy of the gas into pressure energy. The static pressure of the flow path is negative pressure with respect to atmospheric pressure. The liquid is a liquidated material of the gas. A heat pump is equipped with the multistage compressor. Further, document <CIT> shows another example of a compressor structure comprising a diffuser vane.

In the present application, a compressor structure comprising a diffuser vane, and a compressor are provided to reduce an airflow mixing loss brought by gas supplement, and/or reduce a low-speed and low-energy area produced by a suction surface of the diffuser vane when the compressor deviates from a design point.

In order to achieve the above-described object, according to the present invention, a compressor structure is provided. The compressor structure comprising: a diffuser vane, comprising a vane body, wherein a cavity is formed inside the vane body, gas supplement holes are formed on the vane body, and the compressor structure further comprises: a housing, on which a gas supplement passage in communication with the cavity of the diffuser vane is formed, characterized in that the gas supplement holes are all disposed on a suction surface of the vane body such that the gas supplement holes are configured to form a jet flow on the suction surface to blow off a low-speed and low-energy area formed on the suction surface.

In some embodiments, the vane body is made by casting or machining.

In some embodiments, the compressor structure further includes a primary impeller and a secondary impeller, wherein the compressor structure is configured to allow an output airflow of the primary impeller enters the secondary impeller through a primary diffuser provided with the diffuser vane.

In some embodiments, the compressor structure is configured to allow the output airflow of the primary diffuser enters the secondary impeller through a flow passage of a reflux.

In some embodiments, a transition between a flow passage of the primary diffuser and the flow passage of the reflux is formed as a curve.

In some embodiments, a secondary diffuser is mounted on an output end of the secondary impeller.

In the present application, a compressor is also provided. The compressor includes the above-described compressor structure.

The present application forms a jet flow on a suction surface of the diffuser vane by way of gas supplement by the diffuser vane having a hollow structure as well as the gas supplement hole in the back thereof, so as to blow off a low-speed and low-energy area formed on the suction surface, and reduce an airflow mixing loss brought by gas supplement, thereby further improving the aerodynamic efficiency of the centrifugal compressor and enabling to widen the operating range of the compressor whilst improving the aerodynamic performance of the compressor at the design-point.

The present application is further described in detail below with reference to the accompanying drawings and specific embodiments, but not as a delimitation on the present application.

It is an object of the present application to reduce an airflow mixing loss brought by gas supplement and enable to widen the operating range of the compressor whilst improving the performance at the design-point. To this end, in the present invention, a compressor structure comprising a diffuser vane is provided. The diffuser vane includes a vane body <NUM>, wherein a cavity <NUM> is formed inside the vane body <NUM>, and a gas supplement hole <NUM> is formed on the vane body <NUM>. The gas supplement hole <NUM> is disposed on a suction surface of the vane body <NUM>. In some embodiments, the vane body <NUM> is made by casting or machining.

Please referring to <FIG>, when the compressor is operating at a design-point working condition, after the refrigerant gas passes through the primary impeller <NUM>, the absolute velocity C of the airflow consists of Cm and Ct since the refrigerant performs a circular motion along with the impeller. The refrigerant airflow enters the flow passage <NUM> of the primary diffuser at an absolute speed, to impact the diffuser vane at a small attack angle. When the diffuser vane of the present application is not used, if the compressor deviates from the design-point working condition, the absolute airflow angle a of the refrigerant at an outlet of the impeller decreases, and the airflow impacts the vane at a large attack angle, which results in separation of the airflow on the suction surface of the vane and leads to a large low-speed and low-energy area, which finally results in stall and surge of the compressor. In <FIG>, W is a relative speed, U is a rotational speed, C is an absolute speed, and W+U=C.

In the present application, the diffuser vane <NUM> is designed to be hollow, and a miniaturized gas supplement inlet <NUM> is provided on the back of the diffuser vane <NUM>. Accordingly, a jet flow may be formed on a suction surface of the diffuser vane <NUM> by way of gas supplement, so as to blow off a low-speed and low-energy area formed on the suction surface, and reduce an airflow mixing loss brought by gas supplement, thereby further improving the aerodynamic efficiency of the centrifugal compressor and enabling to widen the operating range of the compressor whilst improving the aerodynamic performance of the compressor at the design-point.

Further, by reasonably designing a position, angle and aperture size of the gas supplement hole <NUM>, that is, by reasonably arranging a position, angle and speed of the jet flow, it is possible to effectively suppress the separation of the airflow on the suction surface of the diffuser vane under a non-design-point working condition.

In the present application, the compressor structure includes the above-described diffuser vane <NUM>. The compressor structure further includes a housing, on which a gas supplement passage <NUM> in communication with the cavity <NUM> of the diffuser vane <NUM> is formed.

Under the diffusing effect of the diffuser vane, the stroke of the airflow in the flow passage <NUM> of the primary diffuser is reduced, thereby reducing the losses such as the friction, and improving the total pressure recovery coefficient of the diffuser. At the same time, a jet flow is formed on a suction surface of the diffuser vane <NUM> by way of gas supplement, so as to blow off a low-speed and low-energy area formed on the suction surface, reduce an airflow separation loss, and improve the aerodynamic efficiency of the compressor.

In some embodiments, the compressor structure further includes a primary impeller <NUM> and a secondary impeller <NUM>, wherein an output airflow of the primary impeller <NUM> enters the secondary impeller <NUM> through a primary diffuser provided with the diffuser vane <NUM>. In some embodiments, the output airflow of the primary diffuser enters the secondary impeller <NUM> through a flow passage <NUM> of a reflux. In some embodiments, a transition between a flow passage of the primary diffuser and the flow passage <NUM> of the reflux is formed as a curve. In some embodiments, a secondary diffuser is mounted on an output end of the secondary impeller <NUM>. During operation, the airflow is discharged by a volute <NUM> after sequentially passing through the primary impeller <NUM>, a flow passage <NUM> of the primary diffuser, a flow passage <NUM> of the reflux, the secondary impeller <NUM>, and a flow passage <NUM> of the secondary diffuser. A vane <NUM> of the secondary diffuser vane is provided in a flow passage <NUM> of the secondary diffuser, and a vane <NUM> of the reflux is provided in a flow passage <NUM> of the reflux.

By way of the above-described design, the gas supplement by the jet flow in the back of the diffuser vane <NUM> may effectively reduce a temperature and specific volume of the refrigerant at an outlet of the primary impeller <NUM>, and improve the aerodynamic efficiency of the secondary impeller.

By way of the present design, the gas supplement by the jet flow on the back of the diffuser vane <NUM> may effectively reduce a temperature and specific volume of the refrigerant at an outlet of the first impeller <NUM>, and improve the aerodynamic efficiency of the secondary impeller. By diffusion of the diffuser vane <NUM>, the stroke of the airflow in the flow passage of the primary diffuser may be reduced, thereby reducing the losses such as the friction, and improving the total pressure recovery coefficient of the diffuser. Further, a jet flow is formed on a suction surface of the diffuser vane <NUM> by way of gas supplement by a hollow structure of the diffuser vane <NUM> as well as the gas supplement hole on the back thereof, so as to blow off a low-speed and low-energy area formed on the suction surface, reduce an airflow separation loss, and improve the aerodynamic efficiency of the compressor.

Claim 1:
A compressor structure comprising:
a diffuser vane, comprising a vane body (<NUM>), wherein a cavity (<NUM>) is formed inside the vane body (<NUM>), gas supplement holes (<NUM>) are formed on the vane body (<NUM>), and the compressor structure further comprises: a housing, on which a gas supplement passage (<NUM>) in communication with the cavity (<NUM>) of the diffuser vane (<NUM>) is formed, characterized in that the gas supplement holes (<NUM>) are all disposed on a suction surface of the vane body (<NUM>) such that the gas supplement holes (<NUM>) are configured to form a jet flow on the suction surface to blow off a low-speed and low-energy area formed on the suction surface.