Fuel gas generator ignition test device for simulating whole machine ignition state and working condition design method thereof

Abstract

The invention provides a fuel gas generator ignition test device for simulating the ignition state of a whole machine and a working condition design method thereof, the ignition test device comprises a fuel gas generator, an igniter and a fuel gas process spray pipe, the fuel gas generator is connected with a fuel supply system through a fuel supply pipeline; by designing the volume and the pipeline length of a cavity between a fuel gas generator, a fuel gas process spray pipe and a stop valve and the fuel gas generator, the throat area of a cavitation venturi tube, the inlet pressure of the stop valve and the like, the real working condition when an engine is ignited can be accurately simulated without adopting a turbine; the problems that when the full-size fuel gas generator of the high-performance afterburning cycle engine is subjected to thermal test, a test device is complex in configuration, working condition design simulation criteria are not clear, and working conditions are not covered or are over-assessed are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of gas generator ignition test, and in particular relates to a gas generator ignition test device for simulating the ignition state of a whole machine and a working condition design method thereof. Background Art

[0002] High-performance staged-refueling liquid rocket engines all include gas generators. The gas generators of high-thrust engines are large in size and scale, so scaled-down versions are often used for testing in the early stages of development to verify the feasibility of the injector solution. For non-hypergolic propellants, external energy ignition schemes such as chemical ignition and flare ignition are required. When chemical ignition is used, since the ignition agent is sprayed into the combustion chamber through each injector, the use of scaled-down generators allows for a thorough evaluation of the ignition scheme. When flare ignition is used, the combustion zone spreads from the center to the periphery, and successful ignition of the scaled-down generator does not fully guarantee successful ignition of the full-scale generator. Therefore, conducting squeeze ignition tests of full-scale gas generators is essential for the development of high-thrust staged-refueling cycle engines.

[0003] The purpose of the full-scale oxygen-enriched gas generator squeeze ignition test is to verify the generator ignition process during engine startup. If the test rig is configured to simulate the complete engine state, the configuration may be overly complex. Since the supply solution is difficult to fully align with the complete engine state, the design of the test conditions may result in unclear simulation criteria, incomplete conditions, or over-assessment. For high-thrust engine development, full-scale gas generator hot tests are large-scale and costly, so a reasonable test rig configuration should be used to meet the assessment requirements. Summary of the Invention

[0004] In order to overcome the deficiencies in the prior art, the inventors have conducted intensive research and provided a gas generator ignition test device that simulates the ignition state of the entire machine and a working condition design method thereof, so as to solve the problems of complex test device configuration, unclear working condition design simulation criteria, and non-coverage or over-assessment of working conditions during the hot test of the full-size gas generator of a high-performance regenerative cycle engine.

[0005] The technical solutions provided by the present invention are as follows:

[0006] In a first aspect, a gas generator ignition test device for simulating the ignition state of a whole machine includes a gas generator, an igniter, a gas process nozzle, a cavitation venturi I, a cavitation venturi II, a stop valve I, and a stop valve II;

[0007] The gas generator is connected to the fuel supply system through a fuel supply pipeline. A cavitation venturi tube I is installed on the fuel supply pipeline. A stop valve I is installed downstream of the cavitation venturi tube I.

[0008] The gas generator is connected to the oxidant supply system through an oxidant supply pipeline. A cavitation venturi II is installed on the oxidant supply pipeline, and a stop valve II is installed downstream of the cavitation venturi II.

[0009] Cavitation Venturi I and Cavitation Venturi II are used to control the fuel and oxidant supply flows into the gas generator during the ignition process; Stop Valve I and Stop Valve II are used to control the on-off of the fuel supply pipeline and the oxidant supply pipeline, respectively, to adjust the timing of the fuel and oxidant being introduced into the gas generator;

[0010] The fuel and oxidizer in the gas generator are ignited by the ignition device, and the generated gas is directly discharged into the gas process nozzle; the equivalent flow area of ​​the gas process nozzle throat is equal to the flow area of ​​the engine turbine stator, the volume between the gas process nozzle throat and the gas generator is equal to the volume between the gas generator and the turbine on the engine, and the cavity volume and pipeline length between stop valve I and stop valve II and the gas generator are consistent with the actual pipeline status of the engine.

[0011] In a second aspect, a gas generator ignition test device simulating the ignition state of the entire machine includes a gas generator, an igniter, a gas process nozzle, a throttle ring I, a throttle ring II, a stop valve I and a stop valve II;

[0012] The gas generator is connected to the fuel supply system through a fuel supply pipeline, a stop valve I is installed on the fuel supply pipeline, and a throttle ring I is installed downstream of the stop valve I; the gas generator is connected to the oxidant supply system through an oxidant supply pipeline, a stop valve II is installed on the oxidant supply pipeline, and a throttle ring II is installed downstream of the stop valve II;

[0013] Stop valve I and stop valve II are used to control the on / off of the fuel supply pipeline and the oxidant supply pipeline respectively, and adjust the timing of the fuel and oxidant entering the gas generator;

[0014] Throttle ring I and throttle ring II are used to simulate the flow resistance between the engine shut-off valve and the gas generator head cavity on the fuel supply pipeline and the oxidizer supply pipeline respectively;

[0015] The fuel and oxidizer in the gas generator are ignited by the ignition device, and the generated gas is directly discharged into the gas process nozzle; the equivalent flow area of ​​the gas process nozzle throat is equal to the flow area of ​​the engine turbine stator, the volume between the gas process nozzle throat and the gas generator is equal to the volume between the gas generator and the turbine on the engine, and the cavity volume and pipeline length between stop valve I and stop valve II and the gas generator are consistent with the actual pipeline status of the engine.

[0016] In a third aspect, a method for designing an operating condition for a gas generator ignition test that simulates the ignition state of a complete unit is provided, using the gas generator ignition test apparatus for simulating the ignition state of a complete unit described in the first aspect. The method comprises the following steps:

[0017] The engine starting process is simulated and analyzed to determine the oxidizer flow rate and fuel flow rate when the gas generator is ignited. The total flow rate of the two is the gas flow rate.

[0018] According to the gas flow rate and the equivalent flow area of ​​the process throat, determine the gas pressure when the gas generator enters the steady state;

[0019] Determine the cavitation venturi outlet pressure based on the gas generator steady-state operating pressure, the gas generator injector pressure drop, and the supply line throttle pressure drop;

[0020] According to the outlet pressure of the cavitation venturi, the inlet pressure of the cavitation venturi is selected to make the cavitation venturi in the cavitation state, and then the throat area of ​​the cavitation venturi is obtained according to the inlet pressure of the cavitation venturi.

[0021] In a fourth aspect, a method for designing an operating condition for a gas generator ignition test that simulates the ignition state of a whole unit is provided, using the gas generator ignition test device that simulates the ignition state of a whole unit described in the second aspect. The method comprises the following steps:

[0022] The engine starting process is simulated and analyzed to determine the oxidizer flow rate and fuel flow rate when the gas generator is ignited. The total flow rate of the two is the gas flow rate.

[0023] The shut-off valve inlet pressure during the ignition process is obtained through whole-machine startup simulation, and this pressure is used as the inlet pressure condition during the hot test to carry out subsequent hot test work.

[0024] The present invention provides a gas generator ignition test device that simulates the ignition state of the entire machine and a working condition design method thereof, which has the following beneficial effects:

[0025] The present invention provides a gas generator ignition test device and an operating condition design method for simulating the ignition state of the entire engine. The ignition test device includes a gas generator, an igniter, and a gas process nozzle. The gas generator is connected to a fuel supply system through a fuel supply pipeline. By designing the gas generator, the gas process nozzle, the volume of the cavity between the stop valve and the gas generator, the length of the pipeline, the throat area of ​​the cavitation venturi, the inlet pressure of the stop valve, etc., the actual operating conditions during engine ignition can be accurately simulated without using a turbine. This solves the problems of complex test device configuration, unclear operating condition design simulation criteria, and non-coverage or over-assessment of operating conditions during hot testing of a full-size gas generator of a high-performance regenerative cycle engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a system diagram of a gas generator ignition test device for simulating the ignition state of the entire unit in one embodiment of the present invention;

[0027] Figure 2 This is a system diagram of a gas generator ignition test device for simulating the ignition state of the entire unit in another embodiment of the present invention;

[0028] Figure 3 Schematic diagram for calculating the oxidant flow rate when the gas generator is ignited. DETAILED DESCRIPTION

[0029] The following detailed description of the present invention will make the features and advantages of the present invention more clear and explicit.

[0030] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0031] The present invention provides a gas generator ignition test device that simulates the ignition state of the whole machine, which is suitable for high-pressure (generally 5-30MPa) extrusion hot test and low inlet pressure (generally 0.4-2MPa) hot test. When implementing the high-pressure extrusion hot test, if Figure 1 As shown, the gas generator ignition test device includes: a gas generator, an igniter, a gas process nozzle, a cavitation venturi I, a cavitation venturi II, a stop valve I and a stop valve II;

[0032] The gas generator is connected to the fuel supply system through a fuel supply pipeline. A cavitation venturi tube I is installed on the fuel supply pipeline. A stop valve I is installed downstream of the cavitation venturi tube I.

[0033] The gas generator is connected to the oxidant supply system through an oxidant supply pipeline. A cavitation venturi II is installed on the oxidant supply pipeline, and a stop valve II is installed downstream of the cavitation venturi II.

[0034] Cavitation Venturi I and Cavitation Venturi II are used to control the fuel and oxidant supply flow rates to the gas generator during the ignition process, respectively. Stop Valve I and Stop Valve II are used to control the on-off of the fuel supply pipeline and the oxidant supply pipeline, respectively, and adjust the timing of the fuel and oxidant supply to the gas generator. The cavitation venturi is configured for high-pressure extrusion hot testing to control the propellant supply flow rate to the gas generator during the ignition process.

[0035] The fuel and oxidant in the gas generator are ignited by the ignition device, and the generated gas is directly discharged into the gas process nozzle.

[0036] Because the test device omitted the turbine, the gas flow entered the gas process nozzle directly. To accurately simulate the actual engine ignition conditions, the equivalent flow area at the gas process nozzle throat was determined to simulate the flow area of ​​the engine turbine stator (the equivalent flow area at the gas process nozzle throat = the flow area of ​​the engine turbine stator). The volume between the gas process nozzle throat and the gas generator simulated the volume between the gas generator and the turbine on the engine (the volume between the gas process nozzle throat and the gas generator = the volume between the gas generator and the turbine on the engine). An actual stator assembly could be used in place of the gas process nozzle to assess the stator's ablation resistance during ignition. The cavity volume and pipeline length between shutoff valves I and II and the gas generator were consistent with the actual engine pipeline conditions, simulating the process of cryogenic propellant filling the pipeline after the valves I and II were opened and the gas generator head cavity.

[0037] In a preferred embodiment of the present invention, a throttle ring I is installed downstream of the cavitation venturi I on the fuel supply pipeline, and the throttle ring I simulates the flow resistance between the engine shut-off valve and the gas generator head cavity on the fuel supply pipeline; a throttle ring II is installed downstream of the cavitation venturi II on the oxidant supply pipeline, and the throttle ring II simulates the flow resistance between the engine shut-off valve and the gas generator head cavity on the oxidant supply pipeline.

[0038] In a preferred embodiment of the present invention, the downstream pipeline of the cavitation venturi I on the fuel supply pipeline is divided into a fuel supply branch pipeline and a fuel precooling discharge branch pipeline, a stop valve I is installed on the fuel supply branch pipeline, and a stop valve III is installed on the fuel precooling discharge branch pipeline.

[0039] The downstream pipeline of the cavitation venturi II on the oxidant supply pipeline is divided into an oxidant supply branch pipeline and an oxidant precooling discharge branch pipeline. A stop valve II is installed on the oxidant supply branch pipeline, and a stop valve IV is installed on the oxidant precooling discharge branch pipeline.

[0040] During the hot test at low inlet pressure (0.4~2MPa), if Figure 2 As shown, the cavitation venturi I is not installed on the fuel supply pipeline in the gas generator ignition test device, and a throttle ring I is installed downstream of the stop valve I. The throttle ring I simulates the flow resistance between the engine stop valve I and the gas generator head cavity on the fuel supply pipeline.

[0041] No cavitation venturi II is installed on the oxidizer supply pipeline, and a throttle ring II is installed downstream of the stop valve II. The throttle ring II simulates the flow resistance between the engine stop valve II and the gas generator head cavity on the oxidizer supply pipeline.

[0042] In a preferred embodiment of the present invention, the fuel supply pipeline is connected to the fuel supply branch pipeline and the fuel precooling discharge branch pipeline, the fuel supply branch pipeline is installed with a stop valve I, and the fuel precooling discharge branch pipeline is installed with a stop valve III; the oxidant supply pipeline is connected to the oxidant supply branch pipeline and the oxidant precooling discharge branch pipeline, the oxidant supply branch pipeline is installed with a stop valve II, and the oxidant precooling discharge branch pipeline is installed with a stop valve IV.

[0043] Since the actual flow rate into the gas generator during engine startup gradually increases from zero, the cryogenic propellant may also vaporize into a two-phase state in the pipeline cavity behind shutoff valves I and II. During the design of the test rig, parameters such as the volume and flow resistance of the cavity behind shutoff valves I and II, the volume between the gas process nozzle throat and the gas generator, and the equivalent flow area of ​​the gas process nozzle throat were simulated to be consistent with the engine. By simulating the flow rate at shutoff valves I and II to be consistent with the entire engine ignition process, we can ensure that the actual propellant flow into the gas generator during ignition is similar to that of the entire engine.

[0044] When implementing the high-pressure extrusion hot test, the working condition design method of the gas generator ignition test simulating the ignition state of the whole machine is designed as follows:

[0045] (1) The engine starting process is simulated and analyzed to determine the oxidant flow rate and fuel flow rate during the gas generator ignition. Since the flow rate values ​​are constantly changing, the average value is taken in the relatively stable interval of the flow curve during the ignition process. Figure 3 .

[0046] (2) According to the gas flow rate q m , combined with parameters such as the equivalent flow area of ​​the process throat, determine the gas pressure p when the gas generator enters the steady state i .

[0047]

[0048] Among them, q m is the gas flow rate, which is equal to the total flow rate of the oxidant and the fuel; μ is the flow coefficient of the gas process nozzle throat, which is generally taken as 0.99; A is the equivalent flow area of ​​the gas process nozzle throat; p i is the gas pressure before the throat of the gas process nozzle; R i is the fuel gas constant; T i is the gas temperature; k is the gas adiabatic index.

[0049] (3) According to the steady-state working pressure p of the gas generator i , Gas generator injector pressure drop dP pz And the supply line throttle pressure drop dP jlq , determine the cavitation venturi outlet pressure.

[0050] P eqsg =P i +dP pz +dP jlq .

[0051] Among them, P eqsg is the cavitation venturi outlet pressure, dP pz is the gas generator injector pressure drop, dP jlq It is the pressure drop of the supply line throttle ring.

[0052] (4) According to the cavitation venturi outlet pressure P eqsg , select the appropriate cavitation venturi inlet pressure P iqsg , generally need to ensure P iqsg Greater than 1.3 times P eqsg , to ensure that the cavitation venturi is in a cavitation state, and further use the following formula to calculate the cavitation venturi throat area A qsg .

[0053]

[0054] Where: μ is the cavitation tube flow coefficient, generally taken as 0.9; P s is the saturated vapor pressure of the fuel or oxidant; ρ is the density of the fuel or oxidant; the suffix o in the formula represents the oxygen side, and f represents the fuel side.

[0055] When using an existing cavitation tube for high-flow testing, it may be in a non-cavitation state under steady-state conditions. In this case, ensuring that the cavitation tube does not cavitate when the gas generator is not ignited and pressure is built up can achieve the purpose of the ignition test. It is necessary to ensure that after the gas generator is ignited and pressure is built up, the flow rate decreases when the cavitation tube is in a non-cavitation state, but the gas temperature changes caused by mixture ratio deviations should remain within the material tolerance range. The flow coefficient of the cavitation tube in a non-cavitation state should be obtained in advance through liquid flow testing under corresponding operating conditions.

[0056] (5) A cold adjustment test is required before the test. The head cavity filling degree and the propellant flow rate entering the generator are determined by the rise of the head cavity pressure measuring point, so as to determine the generator ignition sequence. The purpose of adjusting the ignition sequence is achieved by controlling the opening time of the oxidizer valve and the fuel valve.

[0057] (6) By adjusting the inlet pressure of the test device, the mixing ratio and ignition flow rate during generator ignition can be adjusted.

[0058] If the low inlet pressure test scheme without cavitation venturi is adopted, the above steps (2), (3) and (4) are modified to the following step (2):

[0059] (2) The shutoff valve inlet pressure during the ignition process is obtained through the whole-engine startup simulation. This pressure is generally the pressure after the fuel / oxidizer supply system pump and is relatively stable during the ignition process. This pressure is used as the inlet pressure condition for the hot test and subsequent hot test work is carried out. Because the flow resistance between the engine shutoff valve and the gas generator head cavity is simulated by a throttle ring, the propellant flow rate during the ignition process can also be simulated.

[0060] The present invention has been described in detail above with reference to specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present invention. Those skilled in the art will appreciate that various equivalent substitutions, modifications, or improvements may be made to the technical solutions and implementations of the present invention without departing from the spirit and scope of the present invention, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be determined by the appended claims.

[0061] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A gas generator ignition test device simulating the ignition state of the whole machine, characterized in that: It includes a gas generator, an igniter, a gas process nozzle, a cavitation venturi I, a cavitation venturi II, a stop valve I and a stop valve II; The gas generator is connected to the fuel supply system through a fuel supply pipeline, a cavitation venturi tube I is installed on the fuel supply pipeline, and a stop valve I is installed downstream of the cavitation venturi tube I; The gas generator is connected to the oxidant supply system through an oxidant supply pipeline, a cavitation venturi II is installed on the oxidant supply pipeline, and a stop valve II is installed downstream of the cavitation venturi II; The cavitation venturi I and cavitation venturi II are used to control the fuel and oxidant supply flow rates of the gas generator during the ignition process; the stop valve I and stop valve II are used to control the on-off of the fuel supply pipeline and the oxidant supply pipeline, respectively, and adjust the timing of the fuel and oxidant being introduced into the gas generator; The fuel and oxidant in the gas generator are ignited by the ignition device, and the generated gas is directly discharged into the gas process nozzle; The equivalent flow area of ​​the throat of the gas process nozzle is equal to the flow area of ​​the engine turbine stator, the volume between the throat of the gas process nozzle and the gas generator is equal to the volume between the gas generator and the turbine on the engine, and the volume of the cavity between the stop valve I, stop valve II and the gas generator and the pipeline length are consistent with the actual pipeline state of the engine.

2. The gas generator ignition test device for simulating the ignition state of the whole machine according to claim 1, characterized in that: A throttle ring 1 is installed downstream of the cavitation venturi 1 on the fuel supply pipeline, and the throttle ring 1 simulates the flow resistance between the engine stop valve and the gas generator head cavity on the fuel supply pipeline; A throttle ring II is installed downstream of the cavitation venturi II on the oxidant supply pipeline, and the throttle ring II simulates the flow resistance between the engine stop valve and the gas generator head cavity on the oxidant supply pipeline.

3. The gas generator ignition test device for simulating the ignition state of the whole machine according to claim 1, characterized in that: The downstream pipeline of the cavitation venturi I on the fuel supply pipeline is divided into a fuel supply branch pipeline and a fuel precooling discharge branch pipeline, a stop valve I is installed on the fuel supply branch pipeline, and a stop valve III is installed on the fuel precooling discharge branch pipeline; The downstream pipeline of the cavitation venturi II on the oxidant supply pipeline is divided into an oxidant supply branch pipeline and an oxidant precooling discharge branch pipeline. A stop valve II is installed on the oxidant supply branch pipeline, and a stop valve IV is installed on the oxidant precooling discharge branch pipeline.

4. The gas generator ignition test device for simulating the ignition state of the whole machine according to claim 1 or 2, characterized in that: The cavitation venturi I is not installed on the fuel supply pipeline in the gas generator ignition test device, and a throttle ring I is installed downstream of the stop valve I. The throttle ring I simulates the flow resistance between the engine stop valve I and the gas generator head cavity on the fuel supply pipeline; The cavitation venturi II is not installed on the oxidant supply pipeline, and a throttle ring II is installed downstream of the stop valve II. The throttle ring II simulates the flow resistance between the engine stop valve II and the gas generator head cavity on the oxidant supply pipeline.

5. The gas generator ignition test device for simulating the ignition state of the whole machine according to claim 4, characterized in that: The fuel supply pipeline is connected to a fuel supply branch pipeline and a fuel precooling discharge branch pipeline, a stop valve I is installed on the fuel supply branch pipeline, and a stop valve III is installed on the fuel precooling discharge branch pipeline; the oxidant supply pipeline is connected to an oxidant supply branch pipeline and an oxidant precooling discharge branch pipeline, a stop valve II is installed on the oxidant supply branch pipeline, and a stop valve IV is installed on the oxidant precooling discharge branch pipeline.

6. A method for designing the working condition of a gas generator ignition test simulating the ignition state of the whole machine, characterized in that: Using the gas generator ignition test device for simulating the ignition state of the whole machine as claimed in any one of claims 1 to 3, the working condition design method includes the following steps: The engine starting process is simulated and analyzed to determine the oxidant flow rate and fuel flow rate when the gas generator is ignited. The total flow rate of the two is the gas flow rate. According to the gas flow rate and the equivalent flow area of ​​the process throat, determine the gas pressure when the gas generator enters the steady state; Determine the cavitation venturi outlet pressure based on the steady-state working pressure of the gas generator, the pressure drop of the gas generator injector and the pressure drop of the supply line throttle ring; According to the outlet pressure of the cavitation venturi, the inlet pressure of the cavitation venturi is selected to make the cavitation venturi in a cavitation state, and then according to the inlet pressure of the cavitation venturi, the throat area of ​​the cavitation venturi is obtained.

7. The working condition design method for the gas generator ignition test simulating the whole machine ignition state according to claim 6 is characterized in that: In the step of determining the pressure when the gas generator enters a steady state based on the total flow of the oxidant and the fuel in combination with the equivalent flow area of ​​the process throat, the pressure when the gas generator enters a steady state is determined by the following formula: Among them, q m is the gas flow rate, which is equal to the total flow rate of the oxidant and the fuel; μ is the flow coefficient of the throat of the gas process nozzle; A is the equivalent flow area of ​​the throat of the gas process nozzle; p i R is the gas pressure before the throat of the gas process nozzle; i is the fuel gas constant; T i is the gas temperature; k is the gas adiabatic index.

8. The working condition design method for the gas generator ignition test simulating the whole machine ignition state according to claim 7, characterized in that: The step of determining the cavitation venturi outlet pressure according to the steady-state working pressure of the gas generator, the pressure drop of the gas generator injector and the pressure drop of the supply path throttle ring includes: P eqsg =P i +dP pz +dP jlq Among them, P eqsg is the cavitation venturi outlet pressure, dP pz is the gas generator injector pressure drop, dP jlq The throttle pressure drop in the supply line.

9. The working condition design method for the gas generator ignition test simulating the whole machine ignition state according to claim 8, characterized in that: The step of selecting the inlet pressure of the cavitation venturi according to the outlet pressure of the cavitation venturi to make the cavitation venturi in a cavitation state, and then obtaining the throat area of ​​the cavitation venturi according to the inlet pressure of the cavitation venturi, comprises: Among them, A qsg is the throat area of ​​the cavitation venturi; P iqsg is the cavitation venturi inlet pressure, P iqsg ≥1.3P eqsg ; μ is the cavitation tube flow coefficient; P s is the saturated vapor pressure of the fuel or oxidant; ρ is the density of the fuel or oxidant; the suffix o in the formula represents the oxygen side, and f represents the fuel side.

10. A method for designing working conditions of a gas generator ignition test simulating the ignition state of the whole machine, characterized in that: Using the gas generator ignition test device for simulating the ignition state of the whole machine as claimed in claim 4 or 5, the working condition design method includes the following steps: The engine starting process is simulated and analyzed to determine the oxidant flow rate and fuel flow rate when the gas generator is ignited. The total flow rate of the two is the gas flow rate. The inlet pressure of the stop valve during the ignition process is obtained through the whole machine start-up simulation, and this pressure is used as the inlet pressure condition during the hot test to carry out subsequent hot test work.

Images